Koster weather in May

In May, Koster sees average daytime highs of 22°C and overnight lows near 9°C, with 18 mm of rain across 2.2 wet days and about 10.8 hours of daylight. It is the 10th-warmest and 8th-wettest month of the year here.

Highs ease over the month, from about 23°C in the first days to 21°C by the end. The sky is clear or mostly clear about 77% of the time in May, and the air most often feels dry.

Daylight stretches from about 11 hours at the start of May to 10 h 30 min by month's end. Set against the rest of the year, May is Koster's 4th-clearest and 10th-windiest month. For the whole year in context, see Koster's year-round climate.

Daytime high: 22°; 10th warmest
Overnight low: 9°; 4th coldest
Rainfall: 18 mm; 2.2 wet days
Daylight: 10 h 42 min; 6:46 AM – 5:31 PM
Cloud cover: 21%; 4th clearest
Wind: 8 km/h; 10th windiest
Solar energy: 4.33 kWh/m²
Travel score: 8.7; out of 10

Koster is place in North West, South Africa.

Founded: 1860

Air quality: WHO Ambient Air Quality Database. Density & description: Wikidata (CC0), GeoNames.

← April Koster year-round climate June →Best places to visit in May

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

Temperature in May

Average highAverage lowShaded bands: 10–90% of days

Highs ease over the month, from about 23°C in the first days to 21°C by the end.

A typical May day in Koster reaches about 22°C in the afternoon and slips back to 9°C overnight — a 13°C spread between the day's warmth and the night's chill. On most days the high lands between 18°C and 26°C. Set against its neighbours, May runs about 2°C cooler than April and about 3°C warmer than June.

	1	2	3	4	5	6	7	8	9	10	11	12	13	14	15	16	17	18	19	20	21	22	23	24	25	26	27	28	29	30	31
Avg high (°C)	23	23	23	23	23	23	23	23	23	23	23	23	23	23	22	22	22	22	22	22	22	22	22	22	21	21	21	21	21	21	21
Avg low (°C)	11	11	11	11	10	10	10	10	10	10	10	9	9	9	9	9	9	9	8	8	8	8	8	8	8	7	7	7	7	7	7

	Avg high (°C)	Avg low (°C)
1	23	11
2	23	11
3	23	11
4	23	11
5	23	10
6	23	10
7	23	10
8	23	10
9	23	10
10	23	10
11	23	10
12	23	9
13	23	9
14	23	9
15	22	9
16	22	9
17	22	9
18	22	9
19	22	8
20	22	8
21	22	8
22	22	8
23	22	8
24	22	8
25	21	8
26	21	7
27	21	7
28	21	7
29	21	7
30	21	7
31	21	7

Koster weather by month

How May compares with the rest of the year at a glance. May is the 10th-warmest and 8th-wettest month here — the current month is highlighted below.

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

Cloud cover in May

ClearMostly clearPartly cloudyMostly cloudyOvercast

The sky is clear or mostly clear about 77% of the time in May.

Beyond those clear spells, partly cloudy skies cover about 11% of May, with mostly cloudy or overcast conditions the remaining 11%. Skies tend to open up as the month goes on.

	1	2	3	4	5	6	7	8	9	10	11	12	13	14	15	16	17	18	19	20	21	22	23	24	25	26	27	28	29	30	31
Clearer (%)	85	85	85	86	87	88	88	89	90	90	90	91	91	90	89	89	89	89	89	89	89	89	89	89	89	90	90	91	91	91	91
Cloudier (%)	15	15	15	14	13	12	12	11	10	10	10	9	9	10	11	11	11	11	11	11	11	11	11	11	11	10	10	9	9	9	9

	Clearer (%)	Cloudier (%)
1	85	15
2	85	15
3	85	15
4	86	14
5	87	13
6	88	12
7	88	12
8	89	11
9	90	10
10	90	10
11	90	10
12	91	9
13	91	9
14	90	10
15	89	11
16	89	11
17	89	11
18	89	11
19	89	11
20	89	11
21	89	11
22	89	11
23	89	11
24	89	11
25	89	11
26	90	10
27	90	10
28	91	9
29	91	9
30	91	9
31	91	9

Chance of precipitation in May

Any precipitation

Koster gets around 18 mm of rain over 2.2 wet days in May. The line is the day-by-day chance of measurable precipitation.

Day to day, the chance of measurable rain averages around 7% and peaks near 14% on the wettest days. The odds ease toward the end of the month.

	1	2	3	4	5	6	7	8	9	10	11	12	13	14	15	16	17	18	19	20	21	22	23	24	25	26	27	28	29	30	31
Rain chance (%)	14	13	13	12	11	10	10	9	9	8	8	7	7	7	7	6	6	6	6	6	6	6	5	5	5	5	5	5	4	4	4

	Rain chance (%)
1	14
2	13
3	13
4	12
5	11
6	10
7	10
8	9
9	9
10	8
11	8
12	7
13	7
14	7
15	7
16	6
17	6
18	6
19	6
20	6
21	6
22	6
23	5
24	5
25	5
26	5
27	5
28	5
29	4
30	4
31	4

Humidity in May

DryComfortableHumidMuggyOppressiveMiserable

Most of May feels dry — the stacked bands show each day's mix of comfort levels, read off the dew point.

By dew point, May lands in the dry band about 99% of days. It rarely turns muggy — the humid and sticky bands barely register.

	1	2	3	4	5	6	7	8	9	10	11	12	13	14	15	16	17	18	19	20	21	22	23	24	25	26	27	28	29	30	31
Dry (%)	94	95	95	96	96	97	97	97	98	98	98	99	99	99	99	99	99	99	100	100	100	100	100	100	100	100	100	100	100	100	100
Comfortable (%)	6	5	5	4	4	3	3	3	2	2	2	1	1	1	1	1	1	1	0	0	0	0	0	0	0	0	0	0	0	0	0

	Dry (%)	Comfortable (%)
1	94	6
2	95	5
3	95	5
4	96	4
5	96	4
6	97	3
7	97	3
8	97	3
9	98	2
10	98	2
11	98	2
12	99	1
13	99	1
14	99	1
15	99	1
16	99	1
17	99	1
18	99	1
19	100	0
20	100	0
21	100	0
22	100	0
23	100	0
24	100	0
25	100	0
26	100	0
27	100	0
28	100	0
29	100	0
30	100	0
31	100	0

Wind in May

Winds average 8 km/h in May.

Across May, daily wind ranges from about 8 km/h on the calmest days to 8 km/h at its breeziest. It stays fairly steady from day to day.

	1	2	3	4	5	6	7	8	9	10	11	12	13	14	15	16	17	18	19	20	21	22	23	24	25	26	27	28	29	30	31
Wind speed (km/h)	8	8	8	8	8	8	8	8	8	8	8	8	8	8	8	8	8	8	8	8	8	8	8	8	8	8	8	8	8	8	8
Feels	calm	calm	calm	calm	calm	calm	calm	calm	calm	calm	calm	calm	calm	calm	calm	calm	calm	calm	calm	calm	calm	calm	calm	calm	calm	calm	calm	calm	calm	calm	calm

	Wind speed (km/h)	Feels
1	8	calm
2	8	calm
3	8	calm
4	8	calm
5	8	calm
6	8	calm
7	8	calm
8	8	calm
9	8	calm
10	8	calm
11	8	calm
12	8	calm
13	8	calm
14	8	calm
15	8	calm
16	8	calm
17	8	calm
18	8	calm
19	8	calm
20	8	calm
21	8	calm
22	8	calm
23	8	calm
24	8	calm
25	8	calm
26	8	calm
27	8	calm
28	8	calm
29	8	calm
30	8	calm
31	8	calm

Sunrise & sunset in May

DaylightNight

Daylight runs from about 11 hours at the start of May to 10 h 30 min by month's end. The lit band spans sunrise to sunset each day.

Days shrink by about 30 minutes over May. Sunrise moves from 6:38 AM to 6:54 AM, and sunset from 5:41 PM to 5:25 PM.

	1	2	3	4	5	6	7	8	9	10	11	12	13	14	15	16	17	18	19	20	21	22	23	24	25	26	27	28	29	30	31
Daylight (h)	11.0	11.0	11.0	11.0	11.0	10.9	10.9	10.9	10.9	10.9	10.8	10.8	10.8	10.8	10.8	10.7	10.7	10.7	10.7	10.7	10.7	10.6	10.6	10.6	10.6	10.6	10.6	10.6	10.5	10.5	10.5
Sunrise (AM)	6:38	6:39	6:39	6:40	6:41	6:41	6:42	6:42	6:43	6:43	6:44	6:44	6:45	6:45	6:46	6:46	6:47	6:48	6:48	6:49	6:49	6:50	6:50	6:51	6:51	6:52	6:52	6:53	6:53	6:54	6:54
Sunset (PM)	5:41	5:40	5:39	5:38	5:38	5:37	5:36	5:36	5:35	5:34	5:34	5:33	5:32	5:32	5:31	5:31	5:30	5:30	5:29	5:29	5:28	5:28	5:28	5:27	5:27	5:27	5:26	5:26	5:26	5:26	5:25

	Daylight (h)	Sunrise (AM)	Sunset (PM)
1	11.0	6:38	5:41
2	11.0	6:39	5:40
3	11.0	6:39	5:39
4	11.0	6:40	5:38
5	11.0	6:41	5:38
6	10.9	6:41	5:37
7	10.9	6:42	5:36
8	10.9	6:42	5:36
9	10.9	6:43	5:35
10	10.9	6:43	5:34
11	10.8	6:44	5:34
12	10.8	6:44	5:33
13	10.8	6:45	5:32
14	10.8	6:45	5:32
15	10.8	6:46	5:31
16	10.7	6:46	5:31
17	10.7	6:47	5:30
18	10.7	6:48	5:30
19	10.7	6:48	5:29
20	10.7	6:49	5:29
21	10.7	6:49	5:28
22	10.6	6:50	5:28
23	10.6	6:50	5:28
24	10.6	6:51	5:27
25	10.6	6:51	5:27
26	10.6	6:52	5:27
27	10.6	6:52	5:26
28	10.6	6:53	5:26
29	10.5	6:53	5:26
30	10.5	6:54	5:26
31	10.5	6:54	5:25

Solar energy in May

Daily solar energy (kWh/m²)

Average shortwave solar energy reaching the ground each day in May, about 4.33 kWh/m².

For context, solar energy here swings from a low near 3.91 kWh/m² to a high of 6.8 kWh/m² in December across the year — May's 4.33 kWh/m² sits near the bottom.

	1	2	3	4	5	6	7	8	9	10	11	12	13	14	15	16	17	18	19	20	21	22	23	24	25	26	27	28	29	30	31
Solar energy (kWh/m²)	4.5	4.5	4.5	4.5	4.5	4.5	4.5	4.5	4.5	4.4	4.4	4.4	4.4	4.4	4.4	4.3	4.3	4.3	4.3	4.3	4.3	4.2	4.2	4.2	4.2	4.2	4.1	4.1	4.1	4.1	4.1
Level	Bright	Bright	Bright	Bright	Bright	Bright	Bright	Bright	Bright	Bright	Bright	Bright	Bright	Bright	Bright	Bright	Bright	Bright	Bright	Bright	Bright	Bright	Bright	Bright	Bright	Bright	Bright	Bright	Bright	Bright	Bright

	Solar energy (kWh/m²)	Level
1	4.5	Bright
2	4.5	Bright
3	4.5	Bright
4	4.5	Bright
5	4.5	Bright
6	4.5	Bright
7	4.5	Bright
8	4.5	Bright
9	4.5	Bright
10	4.4	Bright
11	4.4	Bright
12	4.4	Bright
13	4.4	Bright
14	4.4	Bright
15	4.4	Bright
16	4.3	Bright
17	4.3	Bright
18	4.3	Bright
19	4.3	Bright
20	4.3	Bright
21	4.3	Bright
22	4.2	Bright
23	4.2	Bright
24	4.2	Bright
25	4.2	Bright
26	4.2	Bright
27	4.1	Bright
28	4.1	Bright
29	4.1	Bright
30	4.1	Bright
31	4.1	Bright

Planning a trip in May

Hazard calendar for Koster

In seasonPeak

None of Koster's seasonal hazards are active in May. The full-year calendar below shows when the rainy season, cyclone risk and dust haze do peak.

Koster's rainy season runs November–March, when most of the year's rain falls.

Rainy season

Jan

Feb

Mar

Apr

May

Jun

Jul

Aug

Sep

Oct

Nov

Dec

Is May a good time to visit Koster?

Our two travel scores rate May for general sightseeing and for beach or pool weather — 0 (poor) to 10 (ideal).

8.7

Sightseeing

2nd-best month of the year

6.1

Beach & pool

10th-best month of the year

May is one of the better times to visit Koster for general sightseeing. The water and warmth also suit a beach or pool day.

What to pack for Koster in May

From May's temperature range, rain chance, sun and wind — what's worth putting in the bag.

In May, Koster sees daytime highs around 22°C and nights near 9°C. Worth packing: light clothes.

light clothes

UV index in Koster in May

LowModerateHighVery highExtreme

Clear-sky midday UV in May peaks around 6 — enough to warrant sun protection. The full-year curve, shaded by WHO exposure level, is below.

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

Air quality in Koster in May

GoodModeratePoorUnhealthyVery unhealthy

Average fine-particle pollution (PM2.5) through the year — so you can see where May falls, not just the annual 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

Location & terrain

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.

3 km

168 m

grassland 50%

16 km

397 m

grassland 54%

80 km

868 m

grassland 58%

treesshrubsgrasslandcroplandartificial surfaces

← April Koster year-round climate June →Best places to visit in May

May weather nearby: Rustenburg 41 km · Ventersdorp 51 km · Marikana 61 km · Carletonville 75 km · Hartbeestfontein-A 77 km · Coligny 78 km · Bagale 78 km · Lichtenburg 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).

	Avg high (°C)	Avg low (°C)
1	23	11
2	23	11
3	23	11
4	23	11
5	23	10
6	23	10
7	23	10
8	23	10
9	23	10
10	23	10
11	23	10
12	23	9
13	23	9
14	23	9
15	22	9
16	22	9
17	22	9
18	22	9
19	22	8
20	22	8
21	22	8
22	22	8
23	22	8
24	22	8
25	21	8
26	21	7
27	21	7
28	21	7
29	21	7
30	21	7
31	21	7

	Clearer (%)	Cloudier (%)
1	85	15
2	85	15
3	85	15
4	86	14
5	87	13
6	88	12
7	88	12
8	89	11
9	90	10
10	90	10
11	90	10
12	91	9
13	91	9
14	90	10
15	89	11
16	89	11
17	89	11
18	89	11
19	89	11
20	89	11
21	89	11
22	89	11
23	89	11
24	89	11
25	89	11
26	90	10
27	90	10
28	91	9
29	91	9
30	91	9
31	91	9

	Rain chance (%)
1	14
2	13
3	13
4	12
5	11
6	10
7	10
8	9
9	9
10	8
11	8
12	7
13	7
14	7
15	7
16	6
17	6
18	6
19	6
20	6
21	6
22	6
23	5
24	5
25	5
26	5
27	5
28	5
29	4
30	4
31	4

	Dry (%)	Comfortable (%)
1	94	6
2	95	5
3	95	5
4	96	4
5	96	4
6	97	3
7	97	3
8	97	3
9	98	2
10	98	2
11	98	2
12	99	1
13	99	1
14	99	1
15	99	1
16	99	1
17	99	1
18	99	1
19	100	0
20	100	0
21	100	0
22	100	0
23	100	0
24	100	0
25	100	0
26	100	0
27	100	0
28	100	0
29	100	0
30	100	0
31	100	0

	Avg high (°C)	Avg low (°C)
1	23	11
2	23	11
3	23	11
4	23	11
5	23	10
6	23	10
7	23	10
8	23	10
9	23	10
10	23	10
11	23	10
12	23	9
13	23	9
14	23	9
15	22	9
16	22	9
17	22	9
18	22	9
19	22	8
20	22	8
21	22	8
22	22	8
23	22	8
24	22	8
25	21	8
26	21	7
27	21	7
28	21	7
29	21	7
30	21	7
31	21	7

	Clearer (%)	Cloudier (%)
1	85	15
2	85	15
3	85	15
4	86	14
5	87	13
6	88	12
7	88	12
8	89	11
9	90	10
10	90	10
11	90	10
12	91	9
13	91	9
14	90	10
15	89	11
16	89	11
17	89	11
18	89	11
19	89	11
20	89	11
21	89	11
22	89	11
23	89	11
24	89	11
25	89	11
26	90	10
27	90	10
28	91	9
29	91	9
30	91	9
31	91	9

	Rain chance (%)
1	14
2	13
3	13
4	12
5	11
6	10
7	10
8	9
9	9
10	8
11	8
12	7
13	7
14	7
15	7
16	6
17	6
18	6
19	6
20	6
21	6
22	6
23	5
24	5
25	5
26	5
27	5
28	5
29	4
30	4
31	4

	Dry (%)	Comfortable (%)
1	94	6
2	95	5
3	95	5
4	96	4
5	96	4
6	97	3
7	97	3
8	97	3
9	98	2
10	98	2
11	98	2
12	99	1
13	99	1
14	99	1
15	99	1
16	99	1
17	99	1
18	99	1
19	100	0
20	100	0
21	100	0
22	100	0
23	100	0
24	100	0
25	100	0
26	100	0
27	100	0
28	100	0
29	100	0
30	100	0
31	100	0

	Avg high (°C)	Avg low (°C)
1	23	11
2	23	11
3	23	11
4	23	11
5	23	10
6	23	10
7	23	10
8	23	10
9	23	10
10	23	10
11	23	10
12	23	9
13	23	9
14	23	9
15	22	9
16	22	9
17	22	9
18	22	9
19	22	8
20	22	8
21	22	8
22	22	8
23	22	8
24	22	8
25	21	8
26	21	7
27	21	7
28	21	7
29	21	7
30	21	7
31	21	7

	Clearer (%)	Cloudier (%)
1	85	15
2	85	15
3	85	15
4	86	14
5	87	13
6	88	12
7	88	12
8	89	11
9	90	10
10	90	10
11	90	10
12	91	9
13	91	9
14	90	10
15	89	11
16	89	11
17	89	11
18	89	11
19	89	11
20	89	11
21	89	11
22	89	11
23	89	11
24	89	11
25	89	11
26	90	10
27	90	10
28	91	9
29	91	9
30	91	9
31	91	9

	Rain chance (%)
1	14
2	13
3	13
4	12
5	11
6	10
7	10
8	9
9	9
10	8
11	8
12	7
13	7
14	7
15	7
16	6
17	6
18	6
19	6
20	6
21	6
22	6
23	5
24	5
25	5
26	5
27	5
28	5
29	4
30	4
31	4

	Dry (%)	Comfortable (%)
1	94	6
2	95	5
3	95	5
4	96	4
5	96	4
6	97	3
7	97	3
8	97	3
9	98	2
10	98	2
11	98	2
12	99	1
13	99	1
14	99	1
15	99	1
16	99	1
17	99	1
18	99	1
19	100	0
20	100	0
21	100	0
22	100	0
23	100	0
24	100	0
25	100	0
26	100	0
27	100	0
28	100	0
29	100	0
30	100	0
31	100	0