Weather in Johannesburg in December

A good month. December is a solid month to be in Johannesburg. You should expect rain on 20 days of the month, which is more days wet than dry.

December ranks 12 of 12 — near the bottom of Johannesburg's year. August is the month that works, and the swing between the two is 33 points, which is a different holiday rather than a slightly better one. Worth keeping in perspective: December is the weakest month of Johannesburg's year and it is still a perfectly good one. The downside here is small.

Rain on 20 of the month's 31 days, 3 of them heavy. At that frequency a wet-weather backup is not a contingency, it is the itinerary — book the indoor things first and treat the clear days as the bonus. Nothing specialised needed — this is the month you pack for the trip rather than for the weather.

What the averages hide

Averages flatten a month, and this one hides a few things: 6 days top 30 °C — hot spells arrive, but they break. Across the twenty years measured, the hottest December day reached 35 °C and the coldest night fell to 5 °C, and the wettest single day dropped 48 mm — roughly 38% of the month's rain in one day.

December is statistically steady but not small: the year-to-year variation is modest in relative terms, yet the wettest December on record still delivered 198 mm against 43 mm in the driest. In a month this wet, even a tame spread is a lot of rain in absolute terms — the 127 mm average is a reasonable planning figure, not a promise.

Wind is light at 8.3 km/h, so the temperature on the page is close to the temperature on your skin, and humidity is unremarkable at 63%.

How December sits in the year

Temperatures hold steady either side: 27 °C in November, 26.8 here, 26.9 in January. Nothing about the timing within the month matters much.

Daylight in December

December is at or near the longest days of Johannesburg's year: 13.8 hours of daylight, holding steady all month. Evenings are the real gain — dinner outdoors still happens in full light.

An inland climate

With no coast nearby, the year swings a fair way — 25.6 °C between the warmest afternoons and the coldest nights, wider than any coastal city at this latitude would manage. At 1767 m, altitude is doing as much work here as latitude: thinner air means fierce sun by day and heat that leaves the moment it sets.

How busy it gets

Off season. The genuine off season: cheapest by a distance, with the caveat that some tours and restaurants close entirely.

Crowd levels are estimated from climate desirability and school-holiday calendars, not from visitor numbers.

December in Johannesburg versus nearby

If Johannesburg is one option among several, the nearby comparison is worth making. Pretoria is the weaker option in December — 3.7 °C warmer, the same number of rain days. Pietermaritzburg is close enough to be a coin toss — within a degree on temperature, 5 days more rain.

So: December is a compromise. August is 33 points better and is what Johannesburg is actually like at its best — worth moving the trip for if that is possible, and worth adjusting expectations for if it is not.

Every month in Johannesburg

See all twelve months in Johannesburg, or where else to go in December.