Johannesburg weather by month
Johannesburg runs from about 10°C in June to 22°C in December, with January the wettest month at 75 mm.
warmest month
December
22°C
coolest month
June
10°C
wettest month
January
75 mm
worst air month
July
71 µg/m³
The whole year, month by month.
| Month | Avg temp | Rain | Sun | PM2.5 |
|---|---|---|---|---|
| January | 20°C | 75 mm | 374 h | 24 |
| February | 21°C | 28 mm | 349 h | 25 |
| March | 20°C | 17 mm | 355 h | 26 |
| April | 15°C | 50 mm | 304 h | 26 |
| May | 15°C | 1 mm | 315 h | 44 |
| June | 10°C | 15 mm | 294 h | 56 |
| July | 11°C | 0 mm | 324 h | 71 |
| August | 14°C | 0 mm | 332 h | 38 |
| September | 17°C | 27 mm | 316 h | 26 |
| October | 18°C | 20 mm | 362 h | 24 |
| November | 21°C | 37 mm | 347 h | 29 |
| December | 22°C | 49 mm | 357 h | 29 |
About 4,029 hours of sun a year. Roughly 34 rainy days a year.
These are long-run climate normals, not a forecast. A given year can sit well outside them. PM2.5 is a global model: near the coast it counts sea salt as fine particulate and reads high against ground stations, sometimes by a factor of two. Use the shape of the year, not the absolute number.
where these numbers come from
- · Temperature, rainfall and sunshine: ECMWF ERA5 reanalysis climate normals via Open-Meteo (CC BY 4.0), fetched once and stored.
- · PM2.5: Copernicus CAMS reanalysis, monthly means. Modelled, not station readings; near coasts CAMS counts sea salt as PM2.5 and reads high.
Last reviewed 2026-05-23. Full method, licences and the list of sources we rejected are on the methodology page.