Heilbron weather in May

In May, Heilbron sees average daytime highs of 21°C and overnight lows near 7°C, with 19 mm of rain across 3.1 wet days and about 10.7 hours of daylight. It is the 10th-warmest and 9th-wettest month of the year here.

Highs ease over the month, from about 22°C in the first days to 19°C by the end. The sky is clear or mostly clear about 73% 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 24 min by month's end. Set against the rest of the year, May is Heilbron's 4th-clearest and 12th-windiest month. For the whole year in context, see Heilbron's year-round climate.

Daytime high: 21°; 10th warmest
Overnight low: 7°; 4th coldest
Rainfall: 19 mm; 3.1 wet days
Daylight: 10 h 42 min; 6:45 AM – 5:24 PM
Cloud cover: 24%; 4th clearest
Wind: 10 km/h; 12th windiest
Solar energy: 4.23 kWh/m²
Travel score: 8.1; out of 10

Heilbron is town in the Free State, South Africa.

Founded: 1872

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

← April Heilbron 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 22°C in the first days to 19°C by the end.

A typical May day in Heilbron reaches about 21°C in the afternoon and slips back to 7°C overnight — a 14°C spread between the day's warmth and the night's chill. On most days the high lands between 17°C and 24°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)	22	22	22	22	22	22	22	22	21	21	21	21	21	21	21	21	21	21	20	20	20	20	20	20	20	20	20	19	19	19	19
Avg low (°C)	9	9	8	8	8	8	8	8	7	7	7	7	7	7	7	7	6	6	6	6	6	6	6	5	5	5	5	5	5	4	4

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

How May really feels in Heilbron

Once humidity and wind are folded in, May averages 0 days that feel above 32°C and 0 that feel at or below 0°C — the comfort signal a plain temperature reading hides.

Days feeling ≥ 32°C

heat index over the day's high

Days feeling ≤ 0°C

wind chill below the day's low

May sits comfortably in between — no days that feel dangerously hot or drop to a hard freeze once humidity and wind are folded in.

Heilbron weather by month

How May compares with the rest of the year at a glance. May is the 10th-warmest and 9th-wettest month here — the current month is highlighted below.

Month	High / Low (°C)	Rainfall (mm)	Wet days	Daylight (hours)	Travel score
Jan	27° / 16°	124	15	13.5	5.9
Feb	27° / 16°	87	12.6	13	6.2
Mar	25° / 14°	81	11.1	12.2	6.9
Apr	23° / 11°	43	6.9	11.4	7.7
May	21° / 7°	19	3.1	10.7	8.1
Jun	18° / 3°	10	1.7	10.3	7.8
Jul	18° / 3°	6	1.1	10.5	7.9
Aug	21° / 6°	15	2.4	11	8.4
Sep	25° / 10°	20	3.2	11.8	8.6
Oct	26° / 13°	76	9.8	12.7	7.1
Nov	26° / 14°	98	12.5	13.3	6.4
Dec	27° / 15°	139	16.6	13.7	5.8

Cloud cover in May

ClearMostly clearPartly cloudyMostly cloudyOvercast

The sky is clear or mostly clear about 73% of the time in May.

Beyond those clear spells, partly cloudy skies cover about 12% of May, with mostly cloudy or overcast conditions the remaining 15%. 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 (%)	84	84	84	86	86	86	86	86	86	86	85	85	85	85	84	84	84	84	83	83	84	84	85	85	86	86	87	87	87	88	88
Cloudier (%)	16	16	16	14	14	14	14	14	14	14	15	15	15	15	16	16	16	16	17	17	16	16	15	15	14	14	13	13	13	12	12

	Clearer (%)	Cloudier (%)
1	84	16
2	84	16
3	84	16
4	86	14
5	86	14
6	86	14
7	86	14
8	86	14
9	86	14
10	86	14
11	85	15
12	85	15
13	85	15
14	85	15
15	84	16
16	84	16
17	84	16
18	84	16
19	83	17
20	83	17
21	84	16
22	84	16
23	85	15
24	85	15
25	86	14
26	86	14
27	87	13
28	87	13
29	87	13
30	88	12
31	88	12

Chance of precipitation in May

Any precipitation

Heilbron gets around 19 mm of rain over 3.1 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 10% and peaks near 17% 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 (%)	17	16	15	14	14	13	13	12	12	11	11	10	10	10	9	9	9	9	9	9	8	8	8	7	7	7	6	6	6	6	6

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

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 100% 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 (%)	100	100	100	100	100	100	100	100	100	100	100	100	100	100	100	100	100	100	100	100	100	100	100	100	100	100	100	100	100	100	100

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

Wind in May

Winds average 10 km/h in May, the calmest month.

Across May, daily wind ranges from about 10 km/h on the calmest days to 10 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)	10	10	10	10	10	10	10	10	10	10	10	10	10	10	10	10	10	10	10	10	10	10	10	10	10	10	10	10	10	10	10
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	10	calm
2	10	calm
3	10	calm
4	10	calm
5	10	calm
6	10	calm
7	10	calm
8	10	calm
9	10	calm
10	10	calm
11	10	calm
12	10	calm
13	10	calm
14	10	calm
15	10	calm
16	10	calm
17	10	calm
18	10	calm
19	10	calm
20	10	calm
21	10	calm
22	10	calm
23	10	calm
24	10	calm
25	10	calm
26	10	calm
27	10	calm
28	10	calm
29	10	calm
30	10	calm
31	10	calm

Sunrise & sunset in May

DaylightNight

Daylight runs from about 11 hours at the start of May to 10 h 24 min by month's end. The lit band spans sunrise to sunset each day.

Days shrink by about 36 minutes over May. Sunrise moves from 6:36 AM to 6:53 AM, and sunset from 5:35 PM to 5:18 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	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	10.6	10.6	10.6	10.6	10.6	10.6	10.5	10.5	10.5	10.5	10.5	10.5	10.4	10.4	10.4
Sunrise (AM)	6:36	6:37	6:37	6:38	6:38	6:39	6:39	6:40	6:41	6:41	6:42	6:42	6:43	6:43	6:44	6:45	6:45	6:46	6:46	6:47	6:47	6:48	6:49	6:49	6:50	6:50	6:51	6:51	6:52	6:52	6:53
Sunset (PM)	5:35	5:34	5:33	5:32	5:31	5:31	5:30	5:29	5:28	5:28	5:27	5:26	5:26	5:25	5:25	5:24	5:24	5:23	5:23	5:22	5:22	5:21	5:21	5:20	5:20	5:20	5:19	5:19	5:19	5:18	5:18

	Daylight (h)	Sunrise (AM)	Sunset (PM)
1	11.0	6:36	5:35
2	11.0	6:37	5:34
3	10.9	6:37	5:33
4	10.9	6:38	5:32
5	10.9	6:38	5:31
6	10.9	6:39	5:31
7	10.8	6:39	5:30
8	10.8	6:40	5:29
9	10.8	6:41	5:28
10	10.8	6:41	5:28
11	10.8	6:42	5:27
12	10.7	6:42	5:26
13	10.7	6:43	5:26
14	10.7	6:43	5:25
15	10.7	6:44	5:25
16	10.7	6:45	5:24
17	10.6	6:45	5:24
18	10.6	6:46	5:23
19	10.6	6:46	5:23
20	10.6	6:47	5:22
21	10.6	6:47	5:22
22	10.6	6:48	5:21
23	10.5	6:49	5:21
24	10.5	6:49	5:20
25	10.5	6:50	5:20
26	10.5	6:50	5:20
27	10.5	6:51	5:19
28	10.5	6:51	5:19
29	10.4	6:52	5:19
30	10.4	6:52	5:18
31	10.4	6:53	5:18

Solar energy in May

Daily solar energy (kWh/m²)

Average shortwave solar energy reaching the ground each day in May, about 4.23 kWh/m².

For context, solar energy here swings from a low near 3.82 kWh/m² to a high of 7.07 kWh/m² in December across the year — May's 4.23 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	4.4	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	4.1	4.0	4.0	4.0	4.0	4.0
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	Moderate

	Solar energy (kWh/m²)	Level
1	4.5	Bright
2	4.5	Bright
3	4.5	Bright
4	4.5	Bright
5	4.4	Bright
6	4.4	Bright
7	4.4	Bright
8	4.4	Bright
9	4.4	Bright
10	4.3	Bright
11	4.3	Bright
12	4.3	Bright
13	4.3	Bright
14	4.3	Bright
15	4.3	Bright
16	4.2	Bright
17	4.2	Bright
18	4.2	Bright
19	4.2	Bright
20	4.2	Bright
21	4.1	Bright
22	4.1	Bright
23	4.1	Bright
24	4.1	Bright
25	4.1	Bright
26	4.1	Bright
27	4.0	Bright
28	4.0	Bright
29	4.0	Bright
30	4.0	Bright
31	4.0	Moderate

Planning a trip in May

Hazard calendar for Heilbron

In seasonPeak

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

Heilbron's rainy season runs October–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 Heilbron?

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

8.1

Sightseeing

3rd-best month of the year

4.7

Beach & pool

10th-best month of the year

May is one of the better times to visit Heilbron for general sightseeing.

What to pack for Heilbron in May

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

In May, Heilbron sees daytime highs around 21°C and nights near 7°C. Worth packing: a warm layer. About 3 days see rain.

a warm layer

UV index in Heilbron 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 Heilbron peaks around January 14 at about 15 (extreme) — sunscreen, a hat and midday shade are essential. It bottoms out near June 20 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	11	8	6	5	5	7	9	10	12	14
Level	Extreme	Extreme	Extreme	Very high	High	Moderate	High	Very high	Very high	Extreme	Extreme	Extreme

	UV index (midday)	Level
Jan	15	Extreme
Feb	13	Extreme
Mar	11	Extreme
Apr	8	Very high
May	6	High
Jun	5	Moderate
Jul	5	High
Aug	7	Very high
Sep	9	Very high
Oct	10	Extreme
Nov	12	Extreme
Dec	14	Extreme

Air quality in Heilbron 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 Heilbron is worst in July — around 103 µg/m³ PM2.5 (unhealthy), about 4.4× the cleanest month (January, 24 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)	24	32	48	64	88	100	103	83	65	44	31	25
Level	Moderate	Moderate	Poor	Unhealthy	Unhealthy	Unhealthy	Unhealthy	Unhealthy	Unhealthy	Poor	Moderate	Moderate

	PM2.5 (µg/m³)	Level
Jan	24	Moderate
Feb	32	Moderate
Mar	48	Poor
Apr	64	Unhealthy
May	88	Unhealthy
Jun	100	Unhealthy
Jul	103	Unhealthy
Aug	83	Unhealthy
Sep	65	Unhealthy
Oct	44	Poor
Nov	31	Moderate
Dec	25	Moderate

Location & terrain

Where is Heilbron?

Heilbron sits at 27.3°S, 28.0°E, 1,539 m above sea level, in South Africa. The nearest listed city is Koppies, 39 km away.

Topography around Heilbron

How much the land rises and falls, and what covers it, within 3, 16 and 80 km of Heilbron.

Within 3 km, the terrain around Heilbron has only modest variations in elevation — a maximum elevation change of 83 m around an average of 1,555 m above sea level; within 16 km, significant variations in elevation — a maximum elevation change of 268 m; within 80 km, significant variations in elevation — a maximum elevation change of 455 m.

The land around Heilbron is covered by grassland (56%) and cropland (22%) within 3 km, grassland (51%) and cropland (47%) within 16 km, and grassland (56%) and cropland (40%) within 80 km.

3 km

83 m

grassland 56%

16 km

268 m

grassland 51%

80 km

455 m

grassland 56%

treesshrubsgrasslandcroplandartificial surfaceswater

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

May weather nearby: Koppies 39 km · Deneysville 45 km · Mamafubedu 46 km · Frankfort 52 km · Sasolburg 54 km · Vanderbijlpark 65 km · Parys 66 km · Vredefort 67 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 Heilbron (-27.2812°, 27.9709°, elevation 1,539 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	22	9
2	22	9
3	22	8
4	22	8
5	22	8
6	22	8
7	22	8
8	22	8
9	21	7
10	21	7
11	21	7
12	21	7
13	21	7
14	21	7
15	21	7
16	21	7
17	21	6
18	21	6
19	20	6
20	20	6
21	20	6
22	20	6
23	20	6
24	20	5
25	20	5
26	20	5
27	20	5
28	19	5
29	19	5
30	19	4
31	19	4

	Clearer (%)	Cloudier (%)
1	84	16
2	84	16
3	84	16
4	86	14
5	86	14
6	86	14
7	86	14
8	86	14
9	86	14
10	86	14
11	85	15
12	85	15
13	85	15
14	85	15
15	84	16
16	84	16
17	84	16
18	84	16
19	83	17
20	83	17
21	84	16
22	84	16
23	85	15
24	85	15
25	86	14
26	86	14
27	87	13
28	87	13
29	87	13
30	88	12
31	88	12

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

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

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

	Clearer (%)	Cloudier (%)
1	84	16
2	84	16
3	84	16
4	86	14
5	86	14
6	86	14
7	86	14
8	86	14
9	86	14
10	86	14
11	85	15
12	85	15
13	85	15
14	85	15
15	84	16
16	84	16
17	84	16
18	84	16
19	83	17
20	83	17
21	84	16
22	84	16
23	85	15
24	85	15
25	86	14
26	86	14
27	87	13
28	87	13
29	87	13
30	88	12
31	88	12

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

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

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

	Clearer (%)	Cloudier (%)
1	84	16
2	84	16
3	84	16
4	86	14
5	86	14
6	86	14
7	86	14
8	86	14
9	86	14
10	86	14
11	85	15
12	85	15
13	85	15
14	85	15
15	84	16
16	84	16
17	84	16
18	84	16
19	83	17
20	83	17
21	84	16
22	84	16
23	85	15
24	85	15
25	86	14
26	86	14
27	87	13
28	87	13
29	87	13
30	88	12
31	88	12

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

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