Climate and average weather in Koster
In Koster, the summers are hot, showery, and partly cloudy and the winters are mild and clear.
Over the course of the year, the temperature in Koster typically varies from 5°C to 28°C, and is rarely below 2°C or above 33°C. January is the hottest month of the year, while July is the coldest.
Based on the travel score, the best time of year to visit Koster for warm-weather activities is from early April to mid October.
- Hottest
- Jan
- 28°
- Coldest
- Jul
- 5°
- Wettest
- Dec
- 121 mm
- Driest
- Jul
- 3 mm
- Rain / yr
- 607 mm
- 87 wet days
- Daylight
- 10.4–13.6 h
- shortest–longest
- Elevation
- 1,620 m
- 25.9°S
- Clearest
- Jul
- 12% cloud
Koster is place in North West, South Africa.
- Founded
- 1860
Air quality: WHO Ambient Air Quality Database. Density & description: Wikidata (CC0), GeoNames.
Koster 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 April to mid October.
Temperature through the year
Daily average highs and lows in Koster, from 1991–2020 of climate data. The shaded bands show the range most days fall in — 10th to 90th percentile.
The hot season lasts 6.4 months, from September 11 to March 24, with daily high temperatures above 26°C. The hottest month of the year in Koster is January, with an average high of 28°C and low of 18°C.
The cool season lasts 2.1 months, from May 30 to August 2, with daily high temperatures below 21°C. The coldest month of the year in Koster is July, with an average low of 5°C and high of 20°C.
Days typically run about 12°C warmer than nights, with the widest day–night swing (around 14°C) in July.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Avg high (°C) | 28 | 28 | 27 | 24 | 22 | 20 | 20 | 23 | 26 | 28 | 28 | 28 |
| Avg low (°C) | 18 | 18 | 16 | 13 | 9 | 6 | 5 | 8 | 12 | 15 | 16 | 17 |
| Avg high (°C) | Avg low (°C) | |
|---|---|---|
| Jan | 28 | 18 |
| Feb | 28 | 18 |
| Mar | 27 | 16 |
| Apr | 24 | 13 |
| May | 22 | 9 |
| Jun | 20 | 6 |
| Jul | 20 | 5 |
| Aug | 23 | 8 |
| Sep | 26 | 12 |
| Oct | 28 | 15 |
| Nov | 28 | 16 |
| Dec | 28 | 17 |
Average hourly temperature in Koster
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 January afternoons, near 28°C, and coldest before dawn in July, near 5°C.
Koster 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° / 18° | 98 | 14.4 | 13.4 | 5.5 |
| Feb | 28° / 18° | 96 | 12.3 | 12.9 | 5.9 |
| Mar | 27° / 16° | 76 | 11.1 | 12.2 | 6.7 |
| Apr | 24° / 13° | 36 | 6.5 | 11.4 | 7.8 |
| May | 22° / 9° | 18 | 2.2 | 10.8 | 8.7 |
| Jun | 20° / 6° | 8 | 1.2 | 10.4 | 8.4 |
| Jul | 20° / 5° | 3 | 0.5 | 10.5 | 8.5 |
| Aug | 23° / 8° | 8 | 1.4 | 11.1 | 9.0 |
| Sep | 26° / 12° | 14 | 2.2 | 11.8 | 8.5 |
| Oct | 28° / 15° | 52 | 7.8 | 12.6 | 7.0 |
| Nov | 28° / 16° | 78 | 12.1 | 13.3 | 5.9 |
| Dec | 28° / 17° | 121 | 14.8 | 13.6 | 5.5 |
Chance of rain
How likely it is to rain on a typical day, and how that shifts across the wetter and drier seasons.
Koster gets about 607 mm of precipitation a year. On a typical day the chance of rain is some rain, but that rises and falls sharply with the seasons.
The wetter season lasts 5.8 months, from around Oct 16 to Apr 11, peaking in January at about 49% chance on a given day. The drier stretch runs the rest of the year, bottoming out around Jul 15.
December is the wettest month by volume, with 121 mm over about 15 wet days; July is the driest, with 3 mm.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Rain on a day (%) | 47 | 43 | 36 | 22 | 8 | 4 | 2 | 4 | 9 | 24 | 40 | 47 |
| Rain days | 14 | 12 | 11 | 7 | 2 | 1 | 1 | 1 | 2 | 8 | 12 | 15 |
| Rain on a day (%) | Rain days | |
|---|---|---|
| Jan | 47 | 14 |
| Feb | 43 | 12 |
| Mar | 36 | 11 |
| Apr | 22 | 7 |
| May | 8 | 2 |
| Jun | 4 | 1 |
| Jul | 2 | 1 |
| Aug | 4 | 1 |
| Sep | 9 | 2 |
| Oct | 24 | 8 |
| Nov | 40 | 12 |
| Dec | 47 | 15 |
Monthly rainfall
Over a full year, Koster collects about 607 mm of rain across 87 wet days — roughly 51 mm in an average month.
It doesn’t fall evenly. December is the wettest month with 121 mm, while July is the driest at just 3 mm. The three wettest months alone bring about 52% of the year’s total.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Rainfall (mm) | 98 | 96 | 76 | 36 | 18 | 8 | 3 | 8 | 14 | 52 | 78 | 121 |
| Rain days | 14 | 12 | 11 | 7 | 2 | 1 | 1 | 1 | 2 | 8 | 12 | 15 |
| Rainfall (mm) | Rain days | |
|---|---|---|
| Jan | 98 | 14 |
| Feb | 96 | 12 |
| Mar | 76 | 11 |
| Apr | 36 | 7 |
| May | 18 | 2 |
| Jun | 8 | 1 |
| Jul | 3 | 1 |
| Aug | 8 | 1 |
| Sep | 14 | 2 |
| Oct | 52 | 8 |
| Nov | 78 | 12 |
| Dec | 121 | 15 |
Clouds and sunshine
How often the daytime sky is clear, partly cloudy or overcast.
In Koster, 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 April 19 and lasts for 5.8 months, ending around October 13. The clearest month is July, when the sky is clear, mostly clear, or partly cloudy 94% of the time on average.
The cloudier part of the year begins around October 14 and lasts for 6.1 months, ending around April 18. The cloudiest month is December, when it is overcast or mostly cloudy 40% of the time.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Clearer (%) | 63 | 68 | 73 | 77 | 89 | 92 | 94 | 93 | 87 | 77 | 63 | 60 |
| Cloudier (%) | 37 | 32 | 27 | 23 | 11 | 8 | 6 | 7 | 13 | 23 | 37 | 40 |
| Clearer (%) | Cloudier (%) | |
|---|---|---|
| Jan | 63 | 37 |
| Feb | 68 | 32 |
| Mar | 73 | 27 |
| Apr | 77 | 23 |
| May | 89 | 11 |
| Jun | 92 | 8 |
| Jul | 94 | 6 |
| Aug | 93 | 7 |
| Sep | 87 | 13 |
| Oct | 77 | 23 |
| Nov | 63 | 37 |
| Dec | 60 | 40 |
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 January 1, brings about 13 h 36 min of light; the shortest, around June 7, only 10 h 24 min — a swing of roughly 3 h 12 min.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Daylight (h) | 13.4 | 12.9 | 12.2 | 11.4 | 10.8 | 10.4 | 10.5 | 11.1 | 11.8 | 12.6 | 13.3 | 13.6 |
| Sunrise (AM) | 5:38 | 6:00 | 6:16 | 6:31 | 6:46 | 7:01 | 7:02 | 6:44 | 6:11 | 5:39 | 5:19 | 5:20 |
| Sunset (PM) | 7:05 | 6:54 | 6:28 | 5:54 | 5:31 | 5:24 | 5:34 | 5:49 | 6:02 | 6:16 | 6:36 | 6:57 |
| Daylight (h) | Sunrise (AM) | Sunset (PM) | |
|---|---|---|---|
| Jan | 13.4 | 5:38 | 7:05 |
| Feb | 12.9 | 6:00 | 6:54 |
| Mar | 12.2 | 6:16 | 6:28 |
| Apr | 11.4 | 6:31 | 5:54 |
| May | 10.8 | 6:46 | 5:31 |
| Jun | 10.4 | 7:01 | 5:24 |
| Jul | 10.5 | 7:02 | 5:34 |
| Aug | 11.1 | 6:44 | 5:49 |
| Sep | 11.8 | 6:11 | 6:02 |
| Oct | 12.6 | 5:39 | 6:16 |
| Nov | 13.3 | 5:19 | 6:36 |
| Dec | 13.6 | 5:20 | 6:57 |
Sunny days
How many genuinely sunny days each month brings — days the sky stays clear or mostly clear — banded into plain-language zones.
Koster averages about 19 sunny days a month — counting the days the sky stays clear or mostly clear — with a clear seasonal swing between 10 and 27 days.
The sunnier stretch runs 5.8 months, from around Apr 19 to Oct 11. The sunniest month is July, with roughly 27 sunny days (brilliant).
The greyest month is December, down near 11 sunny days — about 60% fewer than the July peak.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Sunny days | 12 | 12 | 15 | 18 | 24 | 25 | 27 | 27 | 23 | 18 | 13 | 11 |
| Sky | Mixed | Mixed | Mixed | Bright | Brilliant | Brilliant | Brilliant | Brilliant | Brilliant | Bright | Mixed | Mixed |
| Sunny days | Sky | |
|---|---|---|
| Jan | 12 | Mixed |
| Feb | 12 | Mixed |
| Mar | 15 | Mixed |
| Apr | 18 | Bright |
| May | 24 | Brilliant |
| Jun | 25 | Brilliant |
| Jul | 27 | Brilliant |
| Aug | 27 | Brilliant |
| Sep | 23 | Brilliant |
| Oct | 18 | Bright |
| Nov | 13 | Mixed |
| Dec | 11 | Mixed |
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 Koster, how humid it feels changes dramatically over the year.
The more humid part of the year lasts 4.3 months, from around November 20 to March 30. The muggiest month is January, when the air feels humid, muggy or worse about 51% of the time.
The most comfortable stretch runs from around March 31 to November 19, and October is the most comfortable month — the air is dry or comfortable 99% of the time.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Dry (%) | 14 | 16 | 33 | 75 | 98 | 100 | 100 | 100 | 99 | 83 | 57 | 26 |
| Comfortable (%) | 36 | 39 | 44 | 21 | 2 | 0 | 0 | 0 | 1 | 16 | 32 | 42 |
| Humid (%) | 46 | 41 | 22 | 3 | 0 | 0 | 0 | 0 | 0 | 1 | 11 | 30 |
| Muggy (%) | 4 | 3 | 1 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 2 |
| Dry (%) | Comfortable (%) | Humid (%) | Muggy (%) | |
|---|---|---|---|---|
| Jan | 14 | 36 | 46 | 4 |
| Feb | 16 | 39 | 41 | 3 |
| Mar | 33 | 44 | 22 | 1 |
| Apr | 75 | 21 | 3 | 0 |
| May | 98 | 2 | 0 | 0 |
| Jun | 100 | 0 | 0 | 0 |
| Jul | 100 | 0 | 0 | 0 |
| Aug | 100 | 0 | 0 | 0 |
| Sep | 99 | 1 | 0 | 0 |
| Oct | 83 | 16 | 1 | 0 |
| Nov | 57 | 32 | 11 | 0 |
| Dec | 26 | 42 | 30 | 2 |
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.
Across the year, average wind speed in Koster is typically calm, near 9 km/h, and varies little with the seasons.
The windier part of the year lasts 4.9 months, from around Jul 28 to Dec 24. The windiest month is September, averaging about 11 km/h (calm).
The calmer part of the year runs from around Dec 25 to Jul 27, with March the calmest month at about 8 km/h.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Wind speed (km/h) | 9 | 8 | 8 | 8 | 8 | 9 | 9 | 10 | 11 | 11 | 10 | 9 |
| Feels | calm | calm | calm | calm | calm | calm | calm | calm | calm | calm | calm | calm |
| Wind speed (km/h) | Feels | |
|---|---|---|
| Jan | 9 | calm |
| Feb | 8 | calm |
| Mar | 8 | calm |
| Apr | 8 | calm |
| May | 8 | calm |
| Jun | 9 | calm |
| Jul | 9 | calm |
| Aug | 10 | calm |
| Sep | 11 | calm |
| Oct | 11 | calm |
| Nov | 10 | calm |
| Dec | 9 | calm |
Hazard calendar for Koster
When the seasonal hazards worth planning around — the rainy season, tropical-cyclone risk and dust haze — are active through the year.
Koster's rainy season runs November–March, when most of the year's rain falls.
Best time to visit Koster
To characterize how pleasant the weather is in Koster throughout the year, we compute two travel scores — one for general sightseeing, one for beach and pool weather.
Around mid April, Koster 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. Based on this score, the best time of year to visit Koster for general outdoor tourist activities is from early April to mid October, with a peak score in the last week of August.
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) | 5.5 | 5.9 | 6.7 | 7.8 | 8.6 | 8.4 | 8.5 | 9.0 | 8.5 | 7.0 | 5.9 | 5.5 |
| Rating | fair | good | good | ideal | ideal | ideal | ideal | ideal | ideal | good | good | good |
| Travel score (0–10) | Rating | |
|---|---|---|
| Jan | 5.5 | fair |
| Feb | 5.9 | good |
| Mar | 6.7 | good |
| Apr | 7.8 | ideal |
| May | 8.6 | ideal |
| Jun | 8.4 | ideal |
| Jul | 8.5 | ideal |
| Aug | 9.0 | ideal |
| Sep | 8.5 | ideal |
| Oct | 7.0 | good |
| Nov | 5.9 | good |
| Dec | 5.5 | good |
The beach/pool score favors clear, rainless days with daytime highs between 24°C and 34°C. Based on this score, the best times of year to visit Koster for hot-weather activities run from early April to early May and again from mid August to mid November, with a peak score in the third week of September.
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 Koster, 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 January (highs near 28°C), the essentials are light clothes, rain gear and sun protection. In the cold season around July (highs near 20°C), pack a warm layer.
In January, Koster sees daytime highs around 28°C and nights near 18°C. Pack light clothes, rain gear and sun protection. About 14 days see rain.
UV index (midday) in Koster 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 Koster peaks around January 13 at about 15 (extreme) — sunscreen, a hat and midday shade are essential. It bottoms out near June 19 at about 5 (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) | 15 | 13 | 12 | 9 | 6 | 5 | 6 | 8 | 9 | 11 | 12 | 14 |
| Level | Extreme | Extreme | Extreme | Very high | High | High | High | Very high | Very high | Extreme | Extreme | Extreme |
| UV index (midday) | Level | |
|---|---|---|
| Jan | 15 | Extreme |
| Feb | 13 | Extreme |
| Mar | 12 | Extreme |
| Apr | 9 | Very high |
| May | 6 | High |
| Jun | 5 | High |
| Jul | 6 | High |
| Aug | 8 | Very high |
| Sep | 9 | Very high |
| Oct | 11 | Extreme |
| Nov | 12 | Extreme |
| Dec | 14 | Extreme |
Average hourly UV index in Koster
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 January the burn window is concentrated in the middle of the day: about 9 hours a day reach index 3 (protection recommended), and 7 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) | 9 | 8.5 | 8 | 7 | 5.5 | 5 | 5 | 6.5 | 7 | 8 | 8.5 | 9 |
| UV ≥ 6 (h/day) | 7 | 6.5 | 6 | 4.5 | 1.5 | 0 | 0 | 3.5 | 4.5 | 6 | 6.5 | 7 |
| UV ≥ 3 (h/day) | UV ≥ 6 (h/day) | |
|---|---|---|
| Jan | 9 | 7 |
| Feb | 8.5 | 6.5 |
| Mar | 8 | 6 |
| Apr | 7 | 4.5 |
| May | 5.5 | 1.5 |
| Jun | 5 | 0 |
| Jul | 5 | 0 |
| Aug | 6.5 | 3.5 |
| Sep | 7 | 4.5 |
| Oct | 8 | 6 |
| Nov | 8.5 | 6.5 |
| Dec | 9 | 7 |
Air quality in Koster 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 Koster is worst in June — around 69 µg/m³ PM2.5 (unhealthy), about 5.0× the cleanest month (December, 14 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) | 15 | 22 | 31 | 46 | 62 | 69 | 66 | 53 | 47 | 28 | 17 | 14 |
| Level | Moderate | Moderate | Moderate | Poor | Unhealthy | Unhealthy | Unhealthy | Poor | Poor | Moderate | Moderate | Moderate |
| PM2.5 (µg/m³) | Level | |
|---|---|---|
| Jan | 15 | Moderate |
| Feb | 22 | Moderate |
| Mar | 31 | Moderate |
| Apr | 46 | Poor |
| May | 62 | Unhealthy |
| Jun | 69 | Unhealthy |
| Jul | 66 | Unhealthy |
| Aug | 53 | Poor |
| Sep | 47 | Poor |
| Oct | 28 | Moderate |
| Nov | 17 | Moderate |
| Dec | 14 | Moderate |
Growing season
Koster 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 | 99 | 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 | 99 | 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. Koster banks about 3,276 degree days a year, and the running total — which growers use to time plantings and predict maturity — climbs fastest around January.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Growing degree days (°C·days) | 408 | 362 | 354 | 257 | 171 | 81 | 78 | 167 | 281 | 356 | 366 | 395 |
| Growing degree days (°C·days) | |
|---|---|
| Jan | 408 |
| Feb | 362 |
| Mar | 354 |
| Apr | 257 |
| May | 171 |
| Jun | 81 |
| Jul | 78 |
| Aug | 167 |
| Sep | 281 |
| Oct | 356 |
| Nov | 366 |
| Dec | 395 |
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.
Koster receives about 5.6 kWh/m² a day of solar energy on average — bright — with a clear seasonal swing between 3.9 and 6.9 kWh/m².
The brighter stretch of the year lasts 6.4 months, from around Aug 31 to Mar 14. The brightest month is December, averaging about 6.8 kWh/m² (intense).
The dimmest month is June, down near 3.9 kWh/m² — roughly 42% less than the December peak.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Solar energy (kWh/m²) | 6.7 | 6.3 | 5.6 | 4.8 | 4.3 | 3.9 | 4.2 | 5.0 | 6.1 | 6.7 | 6.8 | 6.8 |
| Level | Intense | Intense | Bright | Bright | Bright | Moderate | Bright | Bright | Intense | Intense | Intense | Intense |
| Solar energy (kWh/m²) | Level | |
|---|---|---|
| Jan | 6.7 | Intense |
| Feb | 6.3 | Intense |
| Mar | 5.6 | Bright |
| Apr | 4.8 | Bright |
| May | 4.3 | Bright |
| Jun | 3.9 | Moderate |
| Jul | 4.2 | Bright |
| Aug | 5.0 | Bright |
| Sep | 6.1 | Intense |
| Oct | 6.7 | Intense |
| Nov | 6.8 | Intense |
| Dec | 6.8 | Intense |
Where is Koster?
Koster sits at 25.9°S, 26.9°E, 1,620 m above sea level, in South Africa. The nearest listed city is Rustenburg, 41 km away.
Topography around Koster
How much the land rises and falls, and what covers it, within 3, 16 and 80 km of Koster.
Within 3 km, the terrain around Koster has only modest variations in elevation — a maximum elevation change of 168 m around an average of 1,581 m above sea level; within 16 km, significant variations in elevation — a maximum elevation change of 397 m; within 80 km, large variations in elevation — a maximum elevation change of 868 m.
The land around Koster is covered by grassland (50%) and cropland (31%) within 3 km, grassland (54%) and cropland (26%) within 16 km, and grassland (58%) within 80 km.
South Africa travel facts
- Travel advisory
- Level 2
- Exercise Increased Caution
- Power plugs
- Type C / M / N
- 230 V · 50 Hz
- Prices
- ≈ 41% of US
- price level, 2025
- GDP per capita
- $6,598
- 2025
- Happiness
- 5.0 / 10
- World Happiness, 2025
- Safe drinking water
- 68%
- of population, 2024
- Homicide rate
- 43.7
- per 100k, 2022
- Road deaths
- 22.2
- per 100k/yr, 2019
- Income group
- Upper middle
- World Bank
- English
- Very high
- EF EPI 602
- 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 Koster (-25.863°, 26.8976°, elevation 1,620 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).