Climate averages 1991–2020
Johannesburg weather
in May.
A mild, fairly dry month: the 10th warmest and the 4th driest of the year. Meets the pleasant-weather rule
Long-term climate patterns, not a forecast for a particular trip.
May is a mild month in Johannesburg: daytime highs average 18.4°C and nights cool to about 5.7°C. By daytime temperature it is the 10th warmest of the 12 months.
Expect about 17 mm of rain on roughly 3 days, which makes May a fairly dry month (the 4th driest of the 12 months). Daylight, from sunrise to sunset, lasts about 10 h 51 min on an average May day.
The nearest other city in this atlas is Alberton (11 km away). In May its highs average 19.6°C, 1.2°C warmer than Johannesburg, with 17 mm of rain.
Among the 95 cities listed in South Africa, Johannesburg ranks 93rd of 95 for the warmest May highs and joint 34th of 95 for the driest May (rainfall, lowest first). The mean May high of those 95 cities is 21.0°C; Johannesburg is 2.6°C cooler than that mean.
From May to June, average highs fall by 2.3°C to 16.1°C, and monthly rainfall falls from 17 mm to 7.8 mm.
The annual picture
May in context
Monthly rainfall
Average total · mmAverages from hourly ERA5 reanalysis data. Actual weather varies from year to year. How these numbers are calculated
Every month, side by side
Johannesburg climate table
| Month | Average highHigh / low | Average low | Rainfall mm/month | Rain days ≥1 mm/day | Daylight hours/dayDaylight h/day |
|---|---|---|---|---|---|
| January | 24.3°C14.1°C | 14.1°C | 132 | 16.4 | 13.614 h |
| February | 24.1°C13.9°C | 13.9°C | 111 | 14.1 | 13.013 h |
| March | 22.8°C12.3°C | 12.3°C | 89 | 12.7 | 12.312 h |
| April | 20.4°C9.3°C | 9.3°C | 45 | 7.3 | 11.511 h |
| May, selected | 18.4°C5.7°C | 5.7°C | 17 | 2.9 | 10.911 h |
| June | 16.1°C2.9°C | 2.9°C | 7.8 | 1.3 | 10.511 h |
| July | 16.3°C2.2°C | 2.2°C | 3.0 | 0.8 | 10.711 h |
| August | 19.4°C4.9°C | 4.9°C | 9.8 | 2.0 | 11.211 h |
| September | 23.4°C8.5°C | 8.5°C | 22 | 3.7 | 11.912 h |
| October | 24.4°C10.9°C | 10.9°C | 75 | 10.7 | 12.713 h |
| November | 24.1°C12.3°C | 12.3°C | 100 | 14.0 | 13.413 h |
| December | 24.3°C13.7°C | 13.7°C | 138 | 18.0 | 13.714 h |
Rainfall is the average of the 30 separate monthly totals. A rain day is a local calendar day with at least 1 mm of precipitation. Daylight is the calculated sunrise-to-sunset length, not measured sunshine.
Compare places
May in nearby cities
- Alberton in MaySouth Africa · 11 kmHigh 19.6°C · Low 6.8°C · 17 mm rain
- Germiston in MaySouth Africa · 12 kmHigh 19.4°C · Low 6.6°C · 15 mm rain
- Randburg in MaySouth Africa · 13 kmHigh 19.6°C · Low 6.6°C · 14 mm rain
- Roodepoort in MaySouth Africa · 18 kmHigh 18.5°C · Low 6.0°C · 18 mm rain
- Tokoza in MaySouth Africa · 19 kmHigh 19.7°C · Low 6.9°C · 15 mm rain
- Soweto in MaySouth Africa · 20 kmHigh 19.0°C · Low 6.6°C · 18 mm rain
- Midrand in MaySouth Africa · 26 kmHigh 19.5°C · Low 6.7°C · 14 mm rain
- Benoni in MaySouth Africa · 28 kmHigh 19.4°C · Low 6.5°C · 15 mm rain
Read the numbers correctly
Climate, not a promise.
These patterns help compare months. They cannot tell you the weather on a specific day of your trip.
Sources, method and limitsHow these numbers are made (what the highs, lows and rain days mean, the sources and the model cell used for Johannesburg) is explained once on the Johannesburg year overview and on the Sources, method and limits page.
Alberton lies in the same rainfall cell, so its rainfall figures are identical to these; temperatures differ because they come from smaller 0.1° cells.