Climate and average weather in Pematangsiantar
In Pematangsiantar, the weather is muggy, hot, wet, and mostly cloudy and remarkably steady, with daytime highs holding near hot levels all year. The wettest stretch peaks around October.
Over the course of the year, the temperature in Pematangsiantar typically varies from 21°C to 30°C, and is rarely below 20°C or above 31°C. May is the hottest month of the year, while December is the coldest.
Based on the travel score, the best times of year to visit Pematangsiantar for warm-weather activities are from early January to mid April and early June to late December.
- Hottest
- May
- 30°
- Coldest
- Dec
- 21°
- Wettest
- Oct
- 375 mm
- Driest
- Feb
- 189 mm
- Rain / yr
- 3301 mm
- 338 wet days
- Daylight
- 11.8–12.2 h
- shortest–longest
- Elevation
- 388 m
- 3.0°N
- Clearest
- Jun
- 84% cloud
Pematangsiantar is city in North Sumatra Province, Indonesia.
- Density
- 3,491/km²
- people per km²
- Founded
- 1871
Air quality: WHO Ambient Air Quality Database. Density & description: Wikidata (CC0), GeoNames.
Pematangsiantar weather by month, at a glance
The whole year in one picture — sky, rain, humidity, temperature and travel score. Click any band to jump to its full chart.
Each stripe is one measure across the whole year, stacked so a single day reads top to bottom. The sky band runs overcast grey on top down to clear blue at the base — more blue means sunnier — followed by the rainfall curve, the humidity band, a temperature strip that tints each stretch of the year by how warm its average high is, and the travel-score line at the foot. Scan straight down any date to read that day across every measure at once; the score climbs highest around early June to late December.
Temperature through the year
Daily average highs and lows in Pematangsiantar, from 1991–2020 of climate data. The shaded bands show the range most days fall in — 10th to 90th percentile.
Temperatures in Pematangsiantar stay fairly even through the year, without a distinct hot or cool season. The warmest month is May, with an average high of 30°C and low of 22°C; the coolest is December, with an average low of 21°C and high of 28°C.
Days typically run about 7°C warmer than nights year-round.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Avg high (°C) | 28 | 28 | 29 | 29 | 30 | 30 | 29 | 29 | 29 | 28 | 28 | 28 |
| Avg low (°C) | 21 | 21 | 21 | 22 | 22 | 22 | 21 | 21 | 21 | 21 | 21 | 21 |
| Avg high (°C) | Avg low (°C) | |
|---|---|---|
| Jan | 28 | 21 |
| Feb | 28 | 21 |
| Mar | 29 | 21 |
| Apr | 29 | 22 |
| May | 30 | 22 |
| Jun | 30 | 22 |
| Jul | 29 | 21 |
| Aug | 29 | 21 |
| Sep | 29 | 21 |
| Oct | 28 | 21 |
| Nov | 28 | 21 |
| Dec | 28 | 21 |
How hot and cold Pematangsiantar really feels
The felt-temperature range through the year — heat index on the day's high (summer humidity), wind chill on the night's low (winter wind). The dashed lines are the plain thermometer; the gap is how much hotter or colder it really feels.
On the hottest afternoons, once humidity is folded in, Pematangsiantar feels like about 33°C (around May 11). About 158 days a year carry some heat stress, peaking in May.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Feels-like high (°C) | 30 | 31 | 32 | 33 | 33 | 33 | 32 | 32 | 32 | 31 | 31 | 30 |
| Air high (°C) | 28 | 28 | 29 | 29 | 30 | 30 | 29 | 29 | 29 | 28 | 28 | 28 |
| Feels-like low (°C) | 21 | 21 | 21 | 22 | 22 | 22 | 21 | 21 | 21 | 21 | 21 | 21 |
| Air low (°C) | 21 | 21 | 21 | 22 | 22 | 22 | 21 | 21 | 21 | 21 | 21 | 21 |
| Feels-like high (°C) | Air high (°C) | Feels-like low (°C) | Air low (°C) | |
|---|---|---|---|---|
| Jan | 30 | 28 | 21 | 21 |
| Feb | 31 | 28 | 21 | 21 |
| Mar | 32 | 29 | 21 | 21 |
| Apr | 33 | 29 | 22 | 22 |
| May | 33 | 30 | 22 | 22 |
| Jun | 33 | 30 | 22 | 22 |
| Jul | 32 | 29 | 21 | 21 |
| Aug | 32 | 29 | 21 | 21 |
| Sep | 32 | 29 | 21 | 21 |
| Oct | 31 | 28 | 21 | 21 |
| Nov | 31 | 28 | 21 | 21 |
| Dec | 30 | 28 | 21 | 21 |
Average hourly temperature in Pematangsiantar
A compact picture of the whole year, hour by hour: each column is a day, each row an hour, and the color is the modeled average temperature. Darker overlays mark night, lighter ones the civil-twilight hours around sunrise and sunset.
Read left to right for the day of the year and top to bottom for the hour of the day; the color is the modeled temperature, cool blues through to hot reds on the same scale as the other charts. A vertical slice is a single day's swing — coolest just before dawn, warmest in the mid-afternoon — while a horizontal slice follows one hour across the seasons. The darker overlay marks night and the lighter one the twilight around sunrise and sunset. Colors run warmest on May afternoons, near 30°C, and coldest before dawn in December, near 21°C.
Pematangsiantar weather by month
Every month at a glance. Click a month for its detailed page.
| Month | High / Low (°C) | Rainfall (mm) | Wet days | Daylight (hours) | Travel score |
|---|---|---|---|---|---|
| Jan | 28° / 21° | 240 | 27.9 | 11.8 | 3.5 |
| Feb | 28° / 21° | 189 | 24.1 | 11.9 | 3.4 |
| Mar | 29° / 21° | 217 | 26.5 | 12 | 3.3 |
| Apr | 29° / 22° | 249 | 28.6 | 12.1 | 2.8 |
| May | 30° / 22° | 265 | 29.2 | 12.1 | 2.8 |
| Jun | 30° / 22° | 231 | 27.1 | 12.2 | 3.0 |
| Jul | 29° / 21° | 237 | 26.7 | 12.2 | 3.2 |
| Aug | 29° / 21° | 274 | 28.8 | 12.1 | 3.0 |
| Sep | 29° / 21° | 361 | 29.4 | 12 | 2.9 |
| Oct | 28° / 21° | 375 | 30.2 | 11.9 | 2.9 |
| Nov | 28° / 21° | 351 | 29.4 | 11.9 | 3.2 |
| Dec | 28° / 21° | 315 | 29.6 | 11.8 | 3.3 |
Chance of rain
How likely it is to rain on a typical day, and how that shifts across the wetter and drier seasons.
Pematangsiantar gets about 3301 mm of precipitation a year. On a typical day the chance of rain is very wet, but that rises and falls sharply with the seasons.
The wetter season lasts 4.7 months, from around Aug 14 to Jan 2, peaking in November at about 99% chance on a given day. The drier stretch runs the rest of the year, bottoming out around Mar 6.
October is the wettest month by volume, with 375 mm over about 30 wet days; February is the driest, with 189 mm.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Rain on a day (%) | 90 | 86 | 86 | 95 | 94 | 90 | 87 | 93 | 98 | 98 | 98 | 95 |
| Rain days | 28 | 24 | 27 | 29 | 29 | 27 | 27 | 29 | 29 | 30 | 29 | 30 |
| Rain on a day (%) | Rain days | |
|---|---|---|
| Jan | 90 | 28 |
| Feb | 86 | 24 |
| Mar | 86 | 27 |
| Apr | 95 | 29 |
| May | 94 | 29 |
| Jun | 90 | 27 |
| Jul | 87 | 27 |
| Aug | 93 | 29 |
| Sep | 98 | 29 |
| Oct | 98 | 30 |
| Nov | 98 | 29 |
| Dec | 95 | 30 |
Monthly rainfall
Over a full year, Pematangsiantar collects about 3301 mm of rain across 338 wet days — roughly 275 mm in an average month.
It doesn’t fall evenly. October is the wettest month with 375 mm, while February is the driest at just 189 mm. The three wettest months alone bring about 33% of the year’s total.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Rainfall (mm) | 240 | 189 | 217 | 249 | 265 | 231 | 237 | 274 | 361 | 375 | 351 | 315 |
| Rain days | 28 | 24 | 27 | 29 | 29 | 27 | 27 | 29 | 29 | 30 | 29 | 30 |
| Rainfall (mm) | Rain days | |
|---|---|---|
| Jan | 240 | 28 |
| Feb | 189 | 24 |
| Mar | 217 | 27 |
| Apr | 249 | 29 |
| May | 265 | 29 |
| Jun | 231 | 27 |
| Jul | 237 | 27 |
| Aug | 274 | 29 |
| Sep | 361 | 29 |
| Oct | 375 | 30 |
| Nov | 351 | 29 |
| Dec | 315 | 30 |
Clouds and sunshine
How often the daytime sky is clear, partly cloudy or overcast.
In Pematangsiantar, the average share of the sky covered by clouds shows mild seasonal variation over the course of the year.
The clearer part of the year begins around May 13 and lasts for 3.1 months, ending around August 13. The clearest month is June, when the sky is clear, mostly clear, or partly cloudy 12% of the time on average.
The cloudier part of the year begins around August 14 and lasts for 4.7 months, ending around January 3. The cloudiest month is October, when it is overcast or mostly cloudy 99% of the time.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Clearer (%) | 8 | 12 | 11 | 5 | 7 | 12 | 11 | 6 | 2 | 1 | 1 | 2 |
| Cloudier (%) | 92 | 88 | 89 | 95 | 93 | 88 | 89 | 94 | 98 | 99 | 99 | 98 |
| Clearer (%) | Cloudier (%) | |
|---|---|---|
| Jan | 8 | 92 |
| Feb | 12 | 88 |
| Mar | 11 | 89 |
| Apr | 5 | 95 |
| May | 7 | 93 |
| Jun | 12 | 88 |
| Jul | 11 | 89 |
| Aug | 6 | 94 |
| Sep | 2 | 98 |
| Oct | 1 | 99 |
| Nov | 1 | 99 |
| Dec | 2 | 98 |
Daylight, sunrise and sunset
Hours of daylight through the year, with sunrise and sunset times.
The gold band is daylight — sunrise runs along its lower edge, sunset along the upper — so it widens toward summer and pinches toward winter, with night the dark area above and below. Close to the equator, Pematangsiantar barely changes through the year: days stay near 12 h 12 min of light in every season.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Daylight (h) | 11.8 | 11.9 | 12.0 | 12.1 | 12.1 | 12.2 | 12.2 | 12.1 | 12.0 | 11.9 | 11.9 | 11.8 |
| Sunrise (AM) | 6:38 | 6:41 | 6:34 | 6:22 | 6:16 | 6:19 | 6:25 | 6:25 | 6:18 | 6:11 | 6:13 | 6:25 |
| Sunset (PM) | 6:28 | 6:35 | 6:33 | 6:26 | 6:24 | 6:29 | 6:34 | 6:31 | 6:19 | 6:07 | 6:05 | 6:15 |
| Daylight (h) | Sunrise (AM) | Sunset (PM) | |
|---|---|---|---|
| Jan | 11.8 | 6:38 | 6:28 |
| Feb | 11.9 | 6:41 | 6:35 |
| Mar | 12.0 | 6:34 | 6:33 |
| Apr | 12.1 | 6:22 | 6:26 |
| May | 12.1 | 6:16 | 6:24 |
| Jun | 12.2 | 6:19 | 6:29 |
| Jul | 12.2 | 6:25 | 6:34 |
| Aug | 12.1 | 6:25 | 6:31 |
| Sep | 12.0 | 6:18 | 6:19 |
| Oct | 11.9 | 6:11 | 6:07 |
| Nov | 11.9 | 6:13 | 6:05 |
| Dec | 11.8 | 6:25 | 6:15 |
Sunny days
How many genuinely sunny days each month brings — days the sky stays clear or mostly clear — banded into plain-language zones.
Pematangsiantar gets about 0 sunny days a month — gloomy — and it barely shifts through the year, holding between 0 and 1 days every month. Clear skies here are a flat line, not a season.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Sunny days | 0 | 1 | 1 | 0 | 0 | 1 | 1 | 0 | 0 | 0 | 0 | 0 |
| Sky | Gloomy | Gloomy | Gloomy | Gloomy | Gloomy | Gloomy | Gloomy | Gloomy | Gloomy | Gloomy | Gloomy | Gloomy |
| Sunny days | Sky | |
|---|---|---|
| Jan | 0 | Gloomy |
| Feb | 1 | Gloomy |
| Mar | 1 | Gloomy |
| Apr | 0 | Gloomy |
| May | 0 | Gloomy |
| Jun | 1 | Gloomy |
| Jul | 1 | Gloomy |
| Aug | 0 | Gloomy |
| Sep | 0 | Gloomy |
| Oct | 0 | Gloomy |
| Nov | 0 | Gloomy |
| Dec | 0 | Gloomy |
Humidity comfort
Share of days at each humidity comfort level, based on the dew point — the measure that tracks how muggy it actually feels.
Humidity comfort is graded by the dew point — the temperature at which the air would be fully saturated — because it tracks how muggy it actually feels far better than relative humidity does. A low dew point feels dry and crisp; a high one feels sticky and oppressive no matter the reading on a humidity gauge.
Pematangsiantar is humid all year round — on a typical day the air feels at least humid, and there is no real dry season to wait for.
The stickiest month is January, when it feels muggy, oppressive or miserable about 100% of the time. Even in January, the mildest month, the air is dry or comfortable only 0% of the time.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Muggy (%) | 42 | 36 | 17 | 3 | 1 | 3 | 9 | 10 | 7 | 9 | 12 | 26 |
| Oppressive (%) | 58 | 64 | 83 | 97 | 99 | 97 | 91 | 90 | 93 | 91 | 88 | 74 |
| Miserable (%) | 0 | 0 | 0 | 0 | 1 | 0 | 0 | 0 | 0 | 0 | 0 | 0 |
| Muggy (%) | Oppressive (%) | Miserable (%) | |
|---|---|---|---|
| Jan | 42 | 58 | 0 |
| Feb | 36 | 64 | 0 |
| Mar | 17 | 83 | 0 |
| Apr | 3 | 97 | 0 |
| May | 1 | 99 | 1 |
| Jun | 3 | 97 | 0 |
| Jul | 9 | 91 | 0 |
| Aug | 10 | 90 | 0 |
| Sep | 7 | 93 | 0 |
| Oct | 9 | 91 | 0 |
| Nov | 12 | 88 | 0 |
| Dec | 26 | 74 | 0 |
Wind
Average wind speed through the year, banded into plain-language speed zones so a number reads as 'breezy' or 'calm' without knowing the scale.
This is the average sustained wind speed at the standard 10 metres above open ground — the steady flow a weather station reports, not the sharper gusts that come and go, which can run half again as fast. It's the number that says whether a place is generally breezy or calm.
Wind in Pematangsiantar is steady company: average speeds sit near 4 km/h — calm — in every month of the year, with no meaningful windy or calm season.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Wind speed (km/h) | 4 | 4 | 4 | 4 | 4 | 4 | 4 | 4 | 4 | 4 | 4 | 4 |
| Feels | calm | calm | calm | calm | calm | calm | calm | calm | calm | calm | calm | calm |
| Wind speed (km/h) | Feels | |
|---|---|---|
| Jan | 4 | calm |
| Feb | 4 | calm |
| Mar | 4 | calm |
| Apr | 4 | calm |
| May | 4 | calm |
| Jun | 4 | calm |
| Jul | 4 | calm |
| Aug | 4 | calm |
| Sep | 4 | calm |
| Oct | 4 | calm |
| Nov | 4 | calm |
| Dec | 4 | calm |
Hazard calendar for Pematangsiantar
When the seasonal hazards worth planning around — the rainy season, tropical-cyclone risk and dust haze — are active through the year.
Pematangsiantar sits in the North Indian Ocean cyclone zone; the season peaks May and October–November.
Best time to visit Pematangsiantar
To characterize how pleasant the weather is in Pematangsiantar throughout the year, we compute two travel scores — one for general sightseeing, one for beach and pool weather.
Around mid June, Pematangsiantar is still near the start of its best-weather window — great conditions with the peak-season crowds not yet at full swing.
Inferred from the travel-score curve; month-by-month visitor numbers are a planned addition.
The travel score favors clear, rainless days with daytime highs between 18°C and 28°C. In Pematangsiantar it holds close to 3.5 all year, so any month is about as good as another for general outdoor tourist activities.
The travel score (filled area), and its constituents: the temperature score (red line), the cloud cover score (blue line), and the precipitation score (green line).
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Travel score (0–10) | 3.5 | 3.4 | 3.2 | 2.8 | 2.8 | 3.0 | 3.1 | 3.0 | 2.9 | 3.0 | 3.2 | 3.3 |
| Rating | poor | poor | poor | poor | poor | poor | poor | poor | poor | poor | poor | poor |
| Travel score (0–10) | Rating | |
|---|---|---|
| Jan | 3.5 | poor |
| Feb | 3.4 | poor |
| Mar | 3.2 | poor |
| Apr | 2.8 | poor |
| May | 2.8 | poor |
| Jun | 3.0 | poor |
| Jul | 3.1 | poor |
| Aug | 3.0 | poor |
| Sep | 2.9 | poor |
| Oct | 3.0 | poor |
| Nov | 3.2 | poor |
| Dec | 3.3 | poor |
The beach/pool score favors clear, rainless days with daytime highs between 24°C and 34°C. In Pematangsiantar it holds close to 4.4 all year, so any month is about as good as another for hot-weather activities.
The beach/pool score (filled area), and its constituents: the temperature score (red line), the cloud cover score (blue line), and the precipitation score (green line).
What to pack for Pematangsiantar, by month
Month by month, what's worth putting in the bag — from the temperature range, rain chance, sun and wind. Tap a month for a quick packing note.
Pematangsiantar packs about the same all year — highs hold near 30°C. Across the year the things worth having are light clothes, rain gear and sun protection.
In May, Pematangsiantar sees daytime highs around 30°C and nights near 22°C. Pack light clothes and rain gear. Worth having: sun protection. About 29 days see rain.
Sea temperature near Pematangsiantar
Average ocean temperature at the nearest coast, month by month, banded into swim-comfort zones — the other half of the beach question.
The sea at the nearest coast (about 57 km away) is warmest in June at about 30°C and coldest in January near 29°C.
The water stays above 20°C all year — warm enough for a swim any month.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Sea temperature (°C) | 29 | 29 | 29 | 30 | 30 | 30 | 30 | 30 | 30 | 29 | 29 | 29 |
| Comfort | Tropical | Tropical | Tropical | Tropical | Tropical | Tropical | Tropical | Tropical | Tropical | Tropical | Tropical | Tropical |
| Sea temperature (°C) | Comfort | |
|---|---|---|
| Jan | 29 | Tropical |
| Feb | 29 | Tropical |
| Mar | 29 | Tropical |
| Apr | 30 | Tropical |
| May | 30 | Tropical |
| Jun | 30 | Tropical |
| Jul | 30 | Tropical |
| Aug | 30 | Tropical |
| Sep | 30 | Tropical |
| Oct | 29 | Tropical |
| Nov | 29 | Tropical |
| Dec | 29 | Tropical |
UV index (midday) in Pematangsiantar by month
Clear-sky midday UV index through the year, shaded by the WHO exposure levels — how much sun protection each month calls for.
Under clear skies, the midday UV index in Pematangsiantar peaks around February 21 at about 15 (extreme) — sunscreen, a hat and midday shade are essential. It bottoms out near June 20 at about 10 (extreme).
The index reaches 3 or more — the level where the WHO recommends sun protection — every month of the year.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| UV index (midday) | 13 | 15 | 14 | 13 | 12 | 10 | 11 | 12 | 14 | 14 | 11 | 11 |
| Level | Extreme | Extreme | Extreme | Extreme | Extreme | Extreme | Extreme | Extreme | Extreme | Extreme | Extreme | Extreme |
| UV index (midday) | Level | |
|---|---|---|
| Jan | 13 | Extreme |
| Feb | 15 | Extreme |
| Mar | 14 | Extreme |
| Apr | 13 | Extreme |
| May | 12 | Extreme |
| Jun | 10 | Extreme |
| Jul | 11 | Extreme |
| Aug | 12 | Extreme |
| Sep | 14 | Extreme |
| Oct | 14 | Extreme |
| Nov | 11 | Extreme |
| Dec | 11 | Extreme |
Average hourly UV index in Pematangsiantar
Modeled clear-sky UV for every hour of every day — when in the day sun protection actually matters.
The whole year hour by hour: each column is a day, each row an hour, and the color is the modeled clear-sky UV index — the midday peak scaled down as the sun sits lower in the sky. Darker overlays mark night, lighter ones the civil-twilight hours around sunrise and sunset.
UV falls off far faster than brightness as the sun drops, so even in February the burn window is concentrated in the middle of the day: about 8 hours a day reach index 3 (protection recommended), and 6.5 hours reach 6 or more. Mornings and late afternoons stay comparatively gentle year round.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| UV ≥ 3 (h/day) | 8 | 8 | 8 | 8 | 8 | 7.5 | 8 | 8 | 8 | 8 | 7.5 | 7.5 |
| UV ≥ 6 (h/day) | 6 | 6.5 | 6.5 | 6 | 6 | 5.5 | 5.5 | 6 | 6.5 | 6 | 5.5 | 5.5 |
| UV ≥ 3 (h/day) | UV ≥ 6 (h/day) | |
|---|---|---|
| Jan | 8 | 6 |
| Feb | 8 | 6.5 |
| Mar | 8 | 6.5 |
| Apr | 8 | 6 |
| May | 8 | 6 |
| Jun | 7.5 | 5.5 |
| Jul | 8 | 5.5 |
| Aug | 8 | 6 |
| Sep | 8 | 6.5 |
| Oct | 8 | 6 |
| Nov | 7.5 | 5.5 |
| Dec | 7.5 | 5.5 |
Air quality in Pematangsiantar by month
Average fine-particle pollution (PM2.5) through the year — so you can see which months the air is worst, not just the yearly average.
Air quality in Pematangsiantar is worst in October — around 40 µg/m³ PM2.5 (poor), and holds fairly steady the rest of the year.
Modeled monthly averages (CAMS reanalysis, 2015–2024).
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| PM2.5 (µg/m³) | 31 | 35 | 38 | 36 | 34 | 33 | 33 | 34 | 39 | 40 | 31 | 29 |
| Level | Moderate | Moderate | Poor | Poor | Moderate | Moderate | Moderate | Moderate | Poor | Poor | Moderate | Moderate |
| PM2.5 (µg/m³) | Level | |
|---|---|---|
| Jan | 31 | Moderate |
| Feb | 35 | Moderate |
| Mar | 38 | Poor |
| Apr | 36 | Poor |
| May | 34 | Moderate |
| Jun | 33 | Moderate |
| Jul | 33 | Moderate |
| Aug | 34 | Moderate |
| Sep | 39 | Poor |
| Oct | 40 | Poor |
| Nov | 31 | Moderate |
| Dec | 29 | Moderate |
Growing season
Pematangsiantar is frost-free year round — even the coldest nights rarely reach freezing, so there is no start or end to the growing season.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Frost-free chance (%) | 100 | 100 | 100 | 100 | 100 | 100 | 100 | 100 | 100 | 100 | 100 | 100 |
| Frost nights | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 |
| Frost-free chance (%) | Frost nights | |
|---|---|---|
| Jan | 100 | 0 |
| Feb | 100 | 0 |
| Mar | 100 | 0 |
| Apr | 100 | 0 |
| May | 100 | 0 |
| Jun | 100 | 0 |
| Jul | 100 | 0 |
| Aug | 100 | 0 |
| Sep | 100 | 0 |
| Oct | 100 | 0 |
| Nov | 100 | 0 |
| Dec | 100 | 0 |
Growing degree days
Growing degree days tally heat above 10°C: each day adds however many degrees its average temperature runs over that threshold, and cold days add nothing. Pematangsiantar banks about 5,463 degree days a year, and the running total — which growers use to time plantings and predict maturity — climbs fastest around May.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Growing degree days (°C·days) | 445 | 410 | 468 | 463 | 486 | 466 | 472 | 467 | 445 | 457 | 438 | 446 |
| Growing degree days (°C·days) | |
|---|---|
| Jan | 445 |
| Feb | 410 |
| Mar | 468 |
| Apr | 463 |
| May | 486 |
| Jun | 466 |
| Jul | 472 |
| Aug | 467 |
| Sep | 445 |
| Oct | 457 |
| Nov | 438 |
| Dec | 446 |
Solar energy
Average daily shortwave solar energy reaching the ground, banded into brightness zones so the number means something at a glance.
Solar energy is how much sunlight actually reaches the ground each day, measured in kilowatt-hours per square metre (kWh/m²) — the combined effect of how long the sun is up, how high it climbs, and how much cloud gets in the way. It's the raw fuel a solar panel has to work with: for scale, 1 kWh/m² a day is dim and wintry, while 7+ is desert-bright.
Pematangsiantar receives about 4.8 kWh/m² a day of solar energy — bright — and it stays remarkably steady, holding between 4.0 and 5.3 kWh/m² all year. For solar panels, output here is a flat line, not a seasonal wave.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Solar energy (kWh/m²) | 4.6 | 5.1 | 5.2 | 5.0 | 4.9 | 5.0 | 5.1 | 5.0 | 4.9 | 4.5 | 4.0 | 4.0 |
| Level | Bright | Bright | Bright | Bright | Bright | Bright | Bright | Bright | Bright | Bright | Bright | Moderate |
| Solar energy (kWh/m²) | Level | |
|---|---|---|
| Jan | 4.6 | Bright |
| Feb | 5.1 | Bright |
| Mar | 5.2 | Bright |
| Apr | 5.0 | Bright |
| May | 4.9 | Bright |
| Jun | 5.0 | Bright |
| Jul | 5.1 | Bright |
| Aug | 5.0 | Bright |
| Sep | 4.9 | Bright |
| Oct | 4.5 | Bright |
| Nov | 4.0 | Bright |
| Dec | 4.0 | Moderate |
Where is Pematangsiantar?
Pematangsiantar sits at 3.0°N, 99.1°E, 388 m above sea level, in Indonesia. The nearest listed city is Pekan Bahapal, 21 km away.
Topography around Pematangsiantar
How much the land rises and falls, and what covers it, within 3, 16 and 80 km of Pematangsiantar.
Within 3 km, the terrain around Pematangsiantar has only modest variations in elevation — a maximum elevation change of 130 m around an average of 382 m above sea level; within 16 km, large variations in elevation — a maximum elevation change of 1,193 m; within 80 km, extreme variations in elevation — a maximum elevation change of 2,429 m.
The land around Pematangsiantar is covered by artificial surfaces (56%) and trees (30%) within 3 km, trees (77%) within 16 km, and trees (70%) within 80 km.
Indonesia travel facts
- Travel advisory
- Level 2
- Exercise Increased Caution
- Power plugs
- Type C / F
- 230 V · 50 Hz
- Prices
- ≈ 29% of US
- price level, 2025
- GDP per capita
- $5,060
- 2025
- Happiness
- 5.6 / 10
- World Happiness, 2025
- Safe drinking water
- 30%
- of population, 2024
- Homicide rate
- 0.3
- per 100k, 2022
- Road deaths
- 11.3
- per 100k/yr, 2019
- Income group
- Upper middle
- World Bank
- English
- Low
- EF EPI 471
- Religion
Sources: World Bank, US State Department, World Happiness Report, WHO/UNICEF, EF EPI, CIA World Factbook.
Data sources
Temperature, precipitation, cloud, humidity, wind and solar figures are a 1991–2020 climatology for Pematangsiantar (2.9595°, 99.0687°, elevation 388 m), computed from hourly ERA5 reanalysis — contains modified Copernicus Climate Change Service information. Sun figures are astronomical calculations, not observations. City data © GeoNames, CC BY 4.0. Map outlines from Natural Earth (public domain); interactive map © Google. Tropical-cyclone seasons are the published climatological basin seasons (NOAA National Hurricane Center / regional warning centres). Sea temperatures are the NOAA OISST v2.1 1991–2020 monthly climatology (public domain), sampled at the nearest ocean point. UV index is derived from CAMS (Copernicus Atmosphere Monitoring Service) clear-sky UV data — contains modified Copernicus Atmosphere Monitoring Service information. Monthly air-quality (PM2.5) seasonality is from the CAMS EAC4 reanalysis (Copernicus Atmosphere Monitoring Service), scaled to the WHO annual mean where available. Topography is sampled from the Copernicus DEM GLO-90 elevation model (© ESA/Airbus) and ESA WorldCover 2021 land cover (CC BY 4.0).