Climate averages 1991–2020
Johannesburg weather
in December.
A warm, wet month: the joint 2nd warmest and the wettest of the year.
Long-term climate patterns, not a forecast for a particular trip.
December is a warm month in Johannesburg: daytime highs average 24.3°C and nights cool to about 13.7°C. By daytime temperature it is the joint 2nd warmest of the 12 months.
Expect about 138 mm of rain on roughly 18 days, which makes December a wet month (the wettest month of the year). Daylight, from sunrise to sunset, lasts about 13 h 45 min on an average December day.
The nearest other city in this atlas is Alberton (11 km away). In December its highs average 25.4°C, 1.1°C warmer than Johannesburg, with 138 mm of rain.
Among the 95 cities listed in South Africa, Johannesburg ranks joint 87th of 95 for the warmest December highs and joint 72nd of 95 for the driest December (rainfall, lowest first). The mean December high of those 95 cities is 26.6°C; Johannesburg is 2.4°C cooler than that mean.
From December to January, average highs rise by 0.1°C to 24.3°C, and monthly rainfall falls from 138 mm to 132 mm.
The annual picture
December 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 | 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, selected | 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
December in nearby cities
- Alberton in DecemberSouth Africa · 11 kmHigh 25.4°C · Low 14.8°C · 138 mm rain
- Germiston in DecemberSouth Africa · 12 kmHigh 25.1°C · Low 14.6°C · 130 mm rain
- Randburg in DecemberSouth Africa · 13 kmHigh 25.4°C · Low 14.8°C · 117 mm rain
- Roodepoort in DecemberSouth Africa · 18 kmHigh 24.4°C · Low 13.9°C · 141 mm rain
- Tokoza in DecemberSouth Africa · 19 kmHigh 25.5°C · Low 14.9°C · 130 mm rain
- Soweto in DecemberSouth Africa · 20 kmHigh 24.9°C · Low 14.6°C · 141 mm rain
- Midrand in DecemberSouth Africa · 26 kmHigh 25.2°C · Low 14.6°C · 117 mm rain
- Benoni in DecemberSouth Africa · 28 kmHigh 25.0°C · Low 14.5°C · 130 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.