Johannesburg weather in September
In September, Johannesburg has daytime highs averaging 24 °C, nights around 8.7 °C, with 3.5 wet days. Figures are 1991–2020 climate normals.
- 23.5°C Average high
- 8.7°C Average low
- 3.5days Wet days
- 22mm Rainfall
- 12h Daylight
Daily temperatures through September
How September develops
Averages for the first, middle and last part of the month, from daily 1991–2020 normals. Chance of rain is the share of years in which that calendar day recorded more than 1 mm.
| Days | Avg high | Avg low | Chance of rain |
|---|---|---|---|
| 1–10 September | 22.7 °C | 7.4 °C | 9 % |
| 11–20 September | 23.7 °C | 9.0 °C | 11 % |
| 21–30 September | 24.1 °C | 9.6 °C | 15 % |
- Average highs rise from 22.7 °C early in September to 24.1 °C by the end of it.
- Rain is most likely over days 21–30 of September (15 % of days) and least likely over days 1–10 (9 %).
What to expect
| Measure | Typical September | Share of the month |
|---|---|---|
| Days above 25 °C | 12 of 30 | 39 % |
| Days above 30 °C | 0.1 of 30 | 0 % |
| Days below 0 °C | 0.1 of 30 | 0 % |
| Days with more than 1 mm rain | 3.5 of 30 | 12 % |
Conditions in September
| Measure | Average |
|---|---|
| Mean temperature | 16 °C |
| Record high (1991–2020) | 31 °C |
| Record low (1991–2020) | -2.1 °C |
| Relative humidity | 42 % |
| Wind speed | 19 km/h |
| Cloud cover | 24 % |
Where Johannesburg ranks in September
| Ranking | Position | Value |
|---|---|---|
| Places with the best weather in Africa in September | 21st of 50 | 92/100 |
| The coolest places in Africa in September | 42nd of 50 | 24 °C |
September compared with the months around it
| Month | Avg high | Rainfall | Cloud |
|---|---|---|---|
| July | 16.4 °C | 3 mm | 12 % |
| August | 19.5 °C | 10 mm | 16 % |
| September | 23.5 °C | 22 mm | 24 % |
| October | 24.6 °C | 73 mm | 40 % |
| November | 24.2 °C | 97 mm | 50 % |
See all twelve months for Johannesburg
- September is the 6th warmest month here.
- It is the 5th driest month of the year.
- It ranks 5th for least cloud cover.
- Days last about 12 hours from sunrise to sunset.
- It rains on 3.5 of 30 days — 12 % of the month.
- Nights are about 15 °C cooler than the middle of the day.
- The hottest September day on record since 1991 reached 31 °C, 7.3 °C above the usual daytime high.
QuestionsSeptember in Johannesburg, answered
How warm is Johannesburg in September?
Daily highs average 24 °C and nights fall to about 8.7 °C, a spread of 15 °C between afternoon and dawn. That makes September the 7th warmest month of the year here.
Does it rain much in Johannesburg in September?
September averages 22 mm of rain, spread over about 4 of the 30 days — 12 % of the month. Cloud cover averages 24 % of the sky.
How long are the days in September?
Johannesburg averages 12 hours between sunrise and sunset in September. Day length is computed from latitude and date, so it is exact rather than modelled — but it says nothing about how much of that time is sunny.
Data sources and method
- ERA5 / ERA5-Land reanalysis — Copernicus Climate Change Service (C3S), ECMWF. Copernicus Licence
- Open-Meteo — Open-Meteo.com. CC BY 4.0
- NOAA OISST v2.1 — NOAA Physical Sciences Laboratory. Public domain
- GeoNames — GeoNames.org. CC BY 4.0
- Normal period
- 1991–2020
- Dataset version
- era5-1991-2020-scores1.1
- Last processed
Measured values come from ERA5 reanalysis and are reproduced unchanged. Calculated by us: daylight hours, beach and comfort scores, monthly rankings, threshold day counts, chance of a wet day by date, ten-day averages within the month. Full formulas are on the methodology page.
Contains modified Copernicus Climate Change Service information 2026. Neither the European Commission nor ECMWF is responsible for any use that may be made of the Copernicus information or data it contains.