Climate and average weather in Mae Sai
In Mae Sai, the summers are humid, sweltering, showery, and mostly clear and the winters are warm and mostly clear.
Over the course of the year, the temperature in Mae Sai typically varies from 14°C to 34°C, and is rarely below 10°C or above 38°C. April is the hottest month of the year, while December is the coldest.
Based on the travel score, the best time of year to visit Mae Sai for warm-weather activities is from mid November to mid February.
- Hottest
- Apr
- 34°
- Coldest
- Dec
- 15°
- Wettest
- Jul
- 455 mm
- Driest
- Feb
- 15 mm
- Rain / yr
- 2193 mm
- 179 wet days
- Daylight
- 10.8–13.2 h
- shortest–longest
- Elevation
- 437 m
- 20.4°N
- Clearest
- Feb
- 23% cloud
Mae Sai is subdistrict municipality in Chiang Rai province, Thailand.
- Density
- 5,365/km²
- people per km²
Air quality: WHO Ambient Air Quality Database. Density & description: Wikidata (CC0), GeoNames.
Mae Sai 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 mid November to mid February.
Temperature through the year
Daily average highs and lows in Mae Sai, from 1991–2020 of climate data. The shaded bands show the range most days fall in — 10th to 90th percentile.
The hot season lasts 3.0 months, from February 28 to May 29, with daily high temperatures above 32°C. The hottest month of the year in Mae Sai is April, with an average high of 34°C and low of 21°C.
The cool season lasts 1.7 months, from November 29 to January 20, with daily high temperatures below 28°C. The coldest month of the year in Mae Sai is December, with an average low of 15°C and high of 26°C.
Days typically run about 11°C warmer than nights, with the widest day–night swing (around 16°C) in February.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Avg high (°C) | 27 | 30 | 33 | 34 | 33 | 32 | 31 | 31 | 31 | 30 | 29 | 26 |
| Avg low (°C) | 14 | 14 | 17 | 21 | 23 | 24 | 24 | 24 | 23 | 22 | 18 | 15 |
| Avg high (°C) | Avg low (°C) | |
|---|---|---|
| Jan | 27 | 14 |
| Feb | 30 | 14 |
| Mar | 33 | 17 |
| Apr | 34 | 21 |
| May | 33 | 23 |
| Jun | 32 | 24 |
| Jul | 31 | 24 |
| Aug | 31 | 24 |
| Sep | 31 | 23 |
| Oct | 30 | 22 |
| Nov | 29 | 18 |
| Dec | 26 | 15 |
How hot and cold Mae Sai 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, Mae Sai feels like about 37°C (around June 6). About 240 days a year carry some heat stress, peaking in June.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Feels-like high (°C) | 27 | 30 | 33 | 36 | 37 | 37 | 36 | 36 | 35 | 33 | 30 | 27 |
| Air high (°C) | 27 | 30 | 33 | 34 | 33 | 32 | 31 | 31 | 31 | 30 | 29 | 26 |
| Feels-like low (°C) | 13 | 14 | 17 | 21 | 23 | 24 | 24 | 24 | 23 | 22 | 18 | 15 |
| Air low (°C) | 14 | 14 | 17 | 21 | 23 | 24 | 24 | 24 | 23 | 22 | 18 | 15 |
| Feels-like high (°C) | Air high (°C) | Feels-like low (°C) | Air low (°C) | |
|---|---|---|---|---|
| Jan | 27 | 27 | 13 | 14 |
| Feb | 30 | 30 | 14 | 14 |
| Mar | 33 | 33 | 17 | 17 |
| Apr | 36 | 34 | 21 | 21 |
| May | 37 | 33 | 23 | 23 |
| Jun | 37 | 32 | 24 | 24 |
| Jul | 36 | 31 | 24 | 24 |
| Aug | 36 | 31 | 24 | 24 |
| Sep | 35 | 31 | 23 | 23 |
| Oct | 33 | 30 | 22 | 22 |
| Nov | 30 | 29 | 18 | 18 |
| Dec | 27 | 26 | 15 | 15 |
Average hourly temperature in Mae Sai
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 April afternoons, near 34°C, and coldest before dawn in December, near 15°C.
Mae Sai 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 | 27° / 14° | 25 | 3.4 | 10.9 | 7.9 |
| Feb | 30° / 14° | 15 | 2.4 | 11.3 | 6.1 |
| Mar | 33° / 17° | 39 | 5.1 | 11.9 | 4.2 |
| Apr | 34° / 21° | 112 | 10.7 | 12.5 | 3.2 |
| May | 33° / 23° | 277 | 21.3 | 13 | 2.8 |
| Jun | 32° / 24° | 349 | 26.7 | 13.2 | 2.4 |
| Jul | 31° / 24° | 455 | 28.5 | 13.1 | 2.5 |
| Aug | 31° / 24° | 424 | 28.7 | 12.7 | 2.6 |
| Sep | 31° / 23° | 287 | 24.2 | 12.1 | 3.0 |
| Oct | 30° / 22° | 134 | 16.7 | 11.5 | 4.3 |
| Nov | 29° / 18° | 47 | 6.5 | 11 | 6.5 |
| Dec | 26° / 15° | 31 | 4.4 | 10.8 | 7.9 |
Chance of rain
How likely it is to rain on a typical day, and how that shifts across the wetter and drier seasons.
Mae Sai gets about 2193 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 5.7 months, from around Apr 28 to Oct 19, peaking in July at about 93% chance on a given day. The drier stretch runs the rest of the year, bottoming out around Feb 11.
July is the wettest month by volume, with 455 mm over about 29 wet days; February is the driest, with 15 mm.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Rain on a day (%) | 11 | 9 | 17 | 36 | 68 | 89 | 91 | 92 | 81 | 53 | 23 | 14 |
| Rain days | 3 | 2 | 5 | 11 | 21 | 27 | 29 | 29 | 24 | 17 | 7 | 4 |
| Rain on a day (%) | Rain days | |
|---|---|---|
| Jan | 11 | 3 |
| Feb | 9 | 2 |
| Mar | 17 | 5 |
| Apr | 36 | 11 |
| May | 68 | 21 |
| Jun | 89 | 27 |
| Jul | 91 | 29 |
| Aug | 92 | 29 |
| Sep | 81 | 24 |
| Oct | 53 | 17 |
| Nov | 23 | 7 |
| Dec | 14 | 4 |
Monthly rainfall
Over a full year, Mae Sai collects about 2193 mm of rain across 179 wet days — roughly 183 mm in an average month.
It doesn’t fall evenly. July is the wettest month with 455 mm, while February is the driest at just 15 mm. The three wettest months alone bring about 56% of the year’s total.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Rainfall (mm) | 25 | 15 | 39 | 112 | 277 | 349 | 455 | 424 | 287 | 134 | 47 | 31 |
| Rain days | 3 | 2 | 5 | 11 | 21 | 27 | 29 | 29 | 24 | 17 | 7 | 4 |
| Rainfall (mm) | Rain days | |
|---|---|---|
| Jan | 25 | 3 |
| Feb | 15 | 2 |
| Mar | 39 | 5 |
| Apr | 112 | 11 |
| May | 277 | 21 |
| Jun | 349 | 27 |
| Jul | 455 | 29 |
| Aug | 424 | 29 |
| Sep | 287 | 24 |
| Oct | 134 | 17 |
| Nov | 47 | 7 |
| Dec | 31 | 4 |
Clouds and sunshine
How often the daytime sky is clear, partly cloudy or overcast.
In Mae Sai, the average share of the sky covered by clouds shows significant seasonal variation over the course of the year.
The clearer part of the year begins around October 12 and lasts for 6.9 months, ending around May 10. The clearest month is February, when the sky is clear, mostly clear, or partly cloudy 89% of the time on average.
The cloudier part of the year begins around May 11 and lasts for 5.1 months, ending around October 11. The cloudiest month is July, when it is overcast or mostly cloudy 96% of the time.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Clearer (%) | 84 | 89 | 85 | 74 | 40 | 7 | 4 | 7 | 23 | 54 | 76 | 79 |
| Cloudier (%) | 16 | 11 | 15 | 26 | 60 | 93 | 96 | 93 | 77 | 46 | 24 | 21 |
| Clearer (%) | Cloudier (%) | |
|---|---|---|
| Jan | 84 | 16 |
| Feb | 89 | 11 |
| Mar | 85 | 15 |
| Apr | 74 | 26 |
| May | 40 | 60 |
| Jun | 7 | 93 |
| Jul | 4 | 96 |
| Aug | 7 | 93 |
| Sep | 23 | 77 |
| Oct | 54 | 46 |
| Nov | 76 | 24 |
| Dec | 79 | 21 |
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. The longest day, around June 2, brings about 13 h 12 min of light; the shortest, around January 1, only 10 h 48 min — a swing of roughly 2 h 24 min.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Daylight (h) | 10.9 | 11.3 | 11.9 | 12.5 | 13.0 | 13.2 | 13.1 | 12.7 | 12.1 | 11.5 | 11.0 | 10.8 |
| Sunrise (AM) | 7:03 | 6:56 | 6:35 | 6:07 | 5:48 | 5:44 | 5:52 | 6:03 | 6:11 | 6:20 | 6:35 | 6:54 |
| Sunset (PM) | 5:56 | 6:14 | 6:26 | 6:35 | 6:46 | 6:58 | 7:00 | 6:46 | 6:18 | 5:51 | 5:36 | 5:40 |
| Daylight (h) | Sunrise (AM) | Sunset (PM) | |
|---|---|---|---|
| Jan | 10.9 | 7:03 | 5:56 |
| Feb | 11.3 | 6:56 | 6:14 |
| Mar | 11.9 | 6:35 | 6:26 |
| Apr | 12.5 | 6:07 | 6:35 |
| May | 13.0 | 5:48 | 6:46 |
| Jun | 13.2 | 5:44 | 6:58 |
| Jul | 13.1 | 5:52 | 7:00 |
| Aug | 12.7 | 6:03 | 6:46 |
| Sep | 12.1 | 6:11 | 6:18 |
| Oct | 11.5 | 6:20 | 5:51 |
| Nov | 11.0 | 6:35 | 5:36 |
| Dec | 10.8 | 6:54 | 5:40 |
Sunny days
How many genuinely sunny days each month brings — days the sky stays clear or mostly clear — banded into plain-language zones.
Mae Sai averages about 12 sunny days a month — counting the days the sky stays clear or mostly clear — with a clear seasonal swing between 0 and 25 days.
The sunnier stretch runs 6.5 months, from around Oct 21 to May 5. The sunniest month is February, with roughly 24 sunny days (brilliant).
The greyest month is August, down near 1 sunny days — about 97% fewer than the February peak.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Sunny days | 21 | 22 | 23 | 17 | 8 | 1 | 1 | 1 | 3 | 11 | 17 | 19 |
| Sky | Bright | Brilliant | Bright | Bright | Gloomy | Gloomy | Gloomy | Gloomy | Gloomy | Mixed | Bright | Bright |
| Sunny days | Sky | |
|---|---|---|
| Jan | 21 | Bright |
| Feb | 22 | Brilliant |
| Mar | 23 | Bright |
| Apr | 17 | Bright |
| May | 8 | Gloomy |
| Jun | 1 | Gloomy |
| Jul | 1 | Gloomy |
| Aug | 1 | Gloomy |
| Sep | 3 | Gloomy |
| Oct | 11 | Mixed |
| Nov | 17 | Bright |
| Dec | 19 | Bright |
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.
In Mae Sai, how humid it feels changes dramatically over the year.
The more humid part of the year lasts 8.1 months, from around March 27 to November 27. The muggiest month is April, when the air feels humid, muggy or worse about 98% of the time.
The most comfortable stretch runs from around November 28 to March 26, and February is the most comfortable month — the air is dry or comfortable 64% of the time.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Dry (%) | 19 | 23 | 6 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 2 | 14 |
| Comfortable (%) | 42 | 42 | 32 | 2 | 0 | 0 | 0 | 0 | 0 | 1 | 8 | 32 |
| Humid (%) | 33 | 27 | 34 | 15 | 1 | 0 | 0 | 0 | 0 | 6 | 32 | 34 |
| Muggy (%) | 6 | 8 | 24 | 45 | 11 | 1 | 0 | 0 | 3 | 19 | 36 | 19 |
| Oppressive (%) | 0 | 0 | 4 | 38 | 77 | 57 | 56 | 65 | 74 | 69 | 22 | 2 |
| Miserable (%) | 0 | 0 | 0 | 0 | 11 | 42 | 44 | 35 | 22 | 4 | 0 | 0 |
| Dry (%) | Comfortable (%) | Humid (%) | Muggy (%) | Oppressive (%) | Miserable (%) | |
|---|---|---|---|---|---|---|
| Jan | 19 | 42 | 33 | 6 | 0 | 0 |
| Feb | 23 | 42 | 27 | 8 | 0 | 0 |
| Mar | 6 | 32 | 34 | 24 | 4 | 0 |
| Apr | 0 | 2 | 15 | 45 | 38 | 0 |
| May | 0 | 0 | 1 | 11 | 77 | 11 |
| Jun | 0 | 0 | 0 | 1 | 57 | 42 |
| Jul | 0 | 0 | 0 | 0 | 56 | 44 |
| Aug | 0 | 0 | 0 | 0 | 65 | 35 |
| Sep | 0 | 0 | 0 | 3 | 74 | 22 |
| Oct | 0 | 1 | 6 | 19 | 69 | 4 |
| Nov | 2 | 8 | 32 | 36 | 22 | 0 |
| Dec | 14 | 32 | 34 | 19 | 2 | 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 Mae Sai 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 | 3 | 3 | 3 | 3 | 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 | 3 | calm |
| Sep | 3 | calm |
| Oct | 3 | calm |
| Nov | 3 | calm |
| Dec | 4 | calm |
Hazard calendar for Mae Sai
When the seasonal hazards worth planning around — the rainy season, tropical-cyclone risk and dust haze — are active through the year.
Mae Sai's monsoon runs May–September, when most of the year's rain falls.
Best time to visit Mae Sai
To characterize how pleasant the weather is in Mae Sai throughout the year, we compute two travel scores — one for general sightseeing, one for beach and pool weather.
Around late January, Mae Sai is still near the tail of its best-weather window — great conditions with the peak-season crowds already thinning.
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. Based on this score, the best time of year to visit Mae Sai for general outdoor tourist activities is from mid November to mid February, with a peak score in the last week of December.
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) | 7.8 | 6.1 | 4.2 | 3.2 | 2.8 | 2.4 | 2.5 | 2.6 | 3.0 | 4.4 | 6.5 | 7.9 |
| Rating | ideal | good | fair | poor | poor | poor | poor | poor | poor | fair | good | ideal |
| Travel score (0–10) | Rating | |
|---|---|---|
| Jan | 7.8 | ideal |
| Feb | 6.1 | good |
| Mar | 4.2 | fair |
| Apr | 3.2 | poor |
| May | 2.8 | poor |
| Jun | 2.4 | poor |
| Jul | 2.5 | poor |
| Aug | 2.6 | poor |
| Sep | 3.0 | poor |
| Oct | 4.4 | fair |
| Nov | 6.5 | good |
| Dec | 7.9 | ideal |
The beach/pool score favors clear, rainless days with daytime highs between 24°C and 34°C. Based on this score, the best time of year to visit Mae Sai for hot-weather activities is from late October to late March, with a peak score in the first week of February.
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 Mae Sai, 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.
For a warm-season trip around April (highs near 34°C), the essentials are light clothes, rain gear and sun protection. In the cold season around December (highs near 26°C), pack light clothes.
In April, Mae Sai sees daytime highs around 34°C and nights near 21°C. Pack light clothes and sun protection. Worth having: rain gear. About 11 days see rain.
UV index (midday) in Mae Sai 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 Mae Sai peaks around July 19 at about 13 (extreme) — sunscreen, a hat and midday shade are essential. It bottoms out near December 20 at about 7 (high).
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) | 7 | 9 | 9 | 10 | 11 | 13 | 13 | 13 | 11 | 10 | 8 | 7 |
| Level | High | Very high | Very high | Very high | Extreme | Extreme | Extreme | Extreme | Extreme | Extreme | Very high | High |
| UV index (midday) | Level | |
|---|---|---|
| Jan | 7 | High |
| Feb | 9 | Very high |
| Mar | 9 | Very high |
| Apr | 10 | Very high |
| May | 11 | Extreme |
| Jun | 13 | Extreme |
| Jul | 13 | Extreme |
| Aug | 13 | Extreme |
| Sep | 11 | Extreme |
| Oct | 10 | Extreme |
| Nov | 8 | Very high |
| Dec | 7 | High |
Average hourly UV index in Mae Sai
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 July the burn window is concentrated in the middle of the day: about 8.5 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) | 6 | 6.5 | 7 | 7.5 | 8 | 8.5 | 8.5 | 8.5 | 8 | 7 | 6.5 | 5.5 |
| UV ≥ 6 (h/day) | 3 | 4 | 4.5 | 5 | 6 | 6.5 | 6.5 | 6.5 | 6 | 5 | 3.5 | 2.5 |
| UV ≥ 3 (h/day) | UV ≥ 6 (h/day) | |
|---|---|---|
| Jan | 6 | 3 |
| Feb | 6.5 | 4 |
| Mar | 7 | 4.5 |
| Apr | 7.5 | 5 |
| May | 8 | 6 |
| Jun | 8.5 | 6.5 |
| Jul | 8.5 | 6.5 |
| Aug | 8.5 | 6.5 |
| Sep | 8 | 6 |
| Oct | 7 | 5 |
| Nov | 6.5 | 3.5 |
| Dec | 5.5 | 2.5 |
Air quality in Mae Sai 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 Mae Sai is worst in April — around 156 µg/m³ PM2.5 (very unhealthy), about 12.0× the cleanest month (July, 13 µg/m³).
Modeled monthly averages (CAMS reanalysis, 2015–2024).
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| PM2.5 (µg/m³) | 23 | 40 | 128 | 156 | 37 | 15 | 13 | 13 | 13 | 14 | 15 | 19 |
| Level | Moderate | Poor | Unhealthy | Very unhealthy | Poor | Moderate | Moderate | Moderate | Moderate | Moderate | Moderate | Moderate |
| PM2.5 (µg/m³) | Level | |
|---|---|---|
| Jan | 23 | Moderate |
| Feb | 40 | Poor |
| Mar | 128 | Unhealthy |
| Apr | 156 | Very unhealthy |
| May | 37 | Poor |
| Jun | 15 | Moderate |
| Jul | 13 | Moderate |
| Aug | 13 | Moderate |
| Sep | 13 | Moderate |
| Oct | 14 | Moderate |
| Nov | 15 | Moderate |
| Dec | 19 | Moderate |
Growing season
Mae Sai 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. Mae Sai banks about 5,534 degree days a year, and the running total — which growers use to time plantings and predict maturity — climbs fastest around June.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Growing degree days (°C·days) | 322 | 342 | 467 | 520 | 552 | 534 | 538 | 534 | 510 | 489 | 398 | 328 |
| Growing degree days (°C·days) | |
|---|---|
| Jan | 322 |
| Feb | 342 |
| Mar | 467 |
| Apr | 520 |
| May | 552 |
| Jun | 534 |
| Jul | 538 |
| Aug | 534 |
| Sep | 510 |
| Oct | 489 |
| Nov | 398 |
| Dec | 328 |
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.
Mae Sai receives about 4.7 kWh/m² a day of solar energy on average — bright — with a clear seasonal swing between 3.8 and 6.3 kWh/m².
The brighter stretch of the year lasts 4.3 months, from around Jan 27 to Jun 5. The brightest month is April, averaging about 6.2 kWh/m² (intense).
The dimmest month is July, down near 3.9 kWh/m² — roughly 36% less than the April peak.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Solar energy (kWh/m²) | 4.4 | 5.4 | 6.1 | 6.3 | 5.4 | 4.5 | 3.9 | 3.9 | 4.2 | 4.3 | 4.3 | 4.0 |
| Level | Bright | Bright | Intense | Intense | Bright | Bright | Moderate | Moderate | Bright | Bright | Bright | Bright |
| Solar energy (kWh/m²) | Level | |
|---|---|---|
| Jan | 4.4 | Bright |
| Feb | 5.4 | Bright |
| Mar | 6.1 | Intense |
| Apr | 6.3 | Intense |
| May | 5.4 | Bright |
| Jun | 4.5 | Bright |
| Jul | 3.9 | Moderate |
| Aug | 3.9 | Moderate |
| Sep | 4.2 | Bright |
| Oct | 4.3 | Bright |
| Nov | 4.3 | Bright |
| Dec | 4.0 | Bright |
Where is Mae Sai?
Mae Sai sits at 20.4°N, 99.9°E, 437 m above sea level, in Thailand. The nearest listed city is Tachilek, 2.0 km away.
Topography around Mae Sai
How much the land rises and falls, and what covers it, within 3, 16 and 80 km of Mae Sai.
Within 3 km, the terrain around Mae Sai has significant variations in elevation — a maximum elevation change of 398 m around an average of 464 m above sea level; within 16 km, very significant variations in elevation — a maximum elevation change of 1,235 m; within 80 km, very significant variations in elevation — a maximum elevation change of 1,977 m.
The land around Mae Sai is covered by trees (54%) and artificial surfaces (33%) within 3 km, trees (61%) and cropland (27%) within 16 km, and trees (81%) within 80 km.
Thailand travel facts
- Travel advisory
- Level 1
- Exercise Normal Precautions
- Power plugs
- Type A / B / C
- 230 V · 50 Hz
- Prices
- ≈ 31% of US
- price level, 2025
- GDP per capita
- $8,057
- 2025
- Happiness
- 6.3 / 10
- World Happiness, 2025
- Homicide rate
- 4.8
- per 100k, 2011
- Road deaths
- 32.2
- per 100k/yr, 2019
- Income group
- Upper middle
- World Bank
- English
- Very low
- EF EPI 402
- 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 Mae Sai (20.4335°, 99.8762°, elevation 437 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. 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).