If you’re planning to spend Christmas in Johannesburg, get ready for warm summer weather and those classic afternoon showers. Daytime temperatures usually hit around 26–27°C (79–81°F), while nights cool off to about 15–17°C (59–63°F). This mix of heat, humidity, and rain shapes the city’s festive vibe.
You’ll see long, bright days with lots of sunshine, but rain is a regular guest. December ranks as one of the wettest months here, so you’ll probably get some short, heavy thunderstorms. Still, the fresh air and the city’s green parks and gardens are hard to beat.
This combination of warmth, rain, and sunshine gives the season a lively feel—pretty different from the winter holidays in the Northern Hemisphere. If you know what to expect, you can plan for both outdoor fun and those sudden downpours that pop up during Johannesburg’s holiday season.
Typical December Weather in Johannesburg
Johannesburg in December brings warm days, frequent afternoon rain, and higher humidity than the dry winter months. You’ll get a good mix of sunshine and showers, with temperatures that are comfortable for most outdoor plans.
Temperature Ranges and Averages
Daytime highs in December usually land between 25°C and 28°C (77°F to 82°F). Occasionally, the temperature pushes close to 30°C (86°F). Nights drop down to about 13°C to 16°C (55°F to 61°F), so evenings feel quite pleasant.
On average, temperatures hover near 20°C (68°F). This balance of warm days and mild nights makes Johannesburg weather in December easy to enjoy, though you’ll want to be ready for sudden changes.
Temperatures creep up as the month goes on. Early December tends to be a bit cooler, while late December brings warmer afternoons. That gradual shift is pretty typical as summer settles in.
Rainfall and Precipitation Patterns
December stands out as one of the wettest months in Johannesburg. The city averages about 120–140 mm of rain during the month, spread across 12 to 15 rainy days. Showers usually hit in the afternoon or evening, often with short, heavy thunderstorms.
Rain doesn’t stick around all day. You might wake up to blue skies, only for clouds to roll in later. This pattern is just part of summer in South Africa’s Highveld region.
Since rain can come down hard, it’s smart to carry waterproof clothing or an umbrella. Streets might flood briefly during stronger storms, so give yourself extra time if you’re heading out.
Humidity Levels in December
Humidity climbs in December compared to Johannesburg’s dry winters. Average relative humidity sits around 60–66%, making the air feel heavier, especially after it rains.
But thanks to the city’s elevation—over 1,700 meters (5,600 feet)—it’s usually more comfortable than coastal South African cities. Nights bring a bit of relief from the daytime stickiness.
Humidity varies from day to day. It peaks during and after storms, while mornings often feel less humid until clouds start building. That’s just the typical summer pattern here.
Sunshine Hours and Daylight Duration
Johannesburg in December gives you long days with loads of sunshine, though you’ll get some cloud cover and summer rainfall. Extended daylight makes outdoor plans easier, but afternoon showers are pretty common.
Average Sunshine and Cloud Cover
December shines as one of Johannesburg’s brightest months. On average, you get about 11 to 12 hours of sunshine per day, adding up to over 370 hours for the month. It’s peak summer, after all.
Even with all that sun, December brings plenty of clouds and rain. With around 19 rainy days, the sky often bounces between clear and overcast. The odds of a totally sunny day run about 40%, which is lower than in the dry season.
So, expect bright mornings and cloudier afternoons. Sun protection matters, since the UV index gets extreme, and it’s easy to burn. Lightweight clothes, hats, and sunscreen are must-haves if you’ll be outside.
| Measure | December Average |
|---|---|
| Daily Sunshine | 11–12 hours |
| Total Sunshine | ~371 hours |
| Chance of Sunny Day | ~41% |
| Rainy Days | ~19 |
Daylight Hours Near Christmas
Around Christmas, Johannesburg enjoys its longest days. You get about 13 hours 30 minutes of daylight, with the sun rising early and setting late. That’s just midsummer in the Southern Hemisphere for you.
Compared to winter, when days shrink to just 10 hours, December offers nearly 3 extra hours of daylight. It’s great for day trips, outdoor meals, or evening gatherings—no need to rush before it gets dark.
The long daylight keeps things warm into the evening. Pair that with frequent sunshine, and you’ve got ideal conditions for outdoor activities, but don’t forget about those late-day thunderstorms that like to crash the party.
| Month | Average Daylight |
|---|---|
| June (winter) | ~10h 20m |
| October | ~12h |
| December | ~13h 30m |
Unique December Weather Phenomena
December in Johannesburg brings some dramatic weather, all thanks to the summer climate. Expect heavy afternoon rain, strong lightning, and sometimes hailstorms that can really shake up the day.
Thunderstorms and Lightning
Thunderstorms show up regularly in Johannesburg during December. Warm days and higher humidity set the stage for storms, especially late in the afternoon.
You’ll probably spot intense lightning—it’s a signature of summer storms here. Since Johannesburg sits high on the Highveld plateau, the altitude and heat make lightning strikes more frequent than in many other cities.
Storms build up fast and usually move through in under an hour. They cool things off, but can also trigger short-term hassles like traffic delays or power cuts.
If you want to be outside, try to get your plans done earlier in the day. Once you hear thunder, it’s smart to head indoors, since lightning here can be both common and risky.
Hail and Other Weather Events
Alongside thunderstorms, hail sometimes makes an appearance in December. Hailstones range from tiny pellets to bigger stones that can ding cars or roofs. These storms don’t happen every day, but they’re not rare during summer.
Hail usually hits during the wildest part of a thunderstorm. Strong updrafts in Johannesburg’s summer let ice form and grow before it falls.
You might also get sudden downpours that briefly flood low spots. While these don’t last long, they can mess with travel and outdoor plans.
Carrying a compact umbrella, wearing light rain gear, and parking under cover all help you deal with these quick changes.
Climate Context: Johannesburg and Gauteng
Johannesburg sits up on a high plateau in Gauteng, and that shapes its mild summers and cooler nights. The city’s elevation and seasonal rhythm influence rainfall, temperature swings, and sunshine hours.
How Altitude Affects December Weather
Johannesburg stands about 1,750 meters (5,740 feet) above sea level. This altitude directly impacts December weather. Even though it’s summer in South Africa, the elevation keeps daytime temperatures from getting too hot.
You’ll see average highs around 25–27°C (77–81°F), which feels warm but not oppressive. Nights drop to about 14–16°C (57–61°F), so evenings are more comfortable than in lower-altitude cities.
Rain falls often in December since it’s the wet season. Showers usually pop up in the afternoon or evening because of convection storms. The thinner air at this altitude also means the sun is more intense. UV levels stay high, so you really need sun protection, even if it’s a bit cloudy.
The mix of warm days, cooler nights, and summer rain defines Johannesburg’s December climate. You can enjoy the outdoors, but always keep an eye out for sudden showers and strong sun.
Comparison to Other Months
December lands right in the middle of Johannesburg’s rainy season, which runs from about October to March. Rainfall peaks during these months, with December averaging 100–120 mm of precipitation.
Winter months like June and July are much drier, with totals often under 10 mm. Nights in winter can get pretty cold, sometimes near 2–4°C (36–39°F), but days usually stay sunny and mild.
Compared to spring (September–October), December is both warmer and wetter. Against late summer (January–February), it’s a touch cooler but still humid. The seasonal cycle in Gauteng is clear: wet and warm summers, dry and cool winters.
So, December brings greener landscapes, higher humidity, and more clouds than most other times of year.
Visiting Johannesburg in December
December in Johannesburg offers warm days, cooler nights, and frequent afternoon thunderstorms. The festive season adds a burst of energy, with outdoor activities and cultural events filling the long days.
What to Pack for December Weather
Prepare for both heat and sudden rain if you’re visiting Johannesburg in December. Daytime highs often hit 24°C to 28°C (75°F to 82°F), while nights cool down to about 14°C to 16°C (57°F to 61°F). Afternoon thunderstorms are common, so rain gear is a must.
Pack lightweight, breathable clothes for warm mornings and afternoons. A light jacket or sweater will help in the evenings when it cools off. Don’t forget a compact umbrella or rain jacket for those quick, heavy storms.
The sun gets intense at Johannesburg’s altitude—about 1,753 meters (5,751 feet). Bring sunscreen, sunglasses, and a wide-brimmed hat for protection during outdoor adventures. Comfortable walking shoes are handy for exploring the city and nearby nature spots.
A small backpack makes it easy to carry water, rain gear, and sun protection as you move around. If you’re heading to holiday events, toss in something a bit dressy for dinners or evening gatherings.
Outdoor Activities and Festive Events
December gives you long daylight hours, with sunrise around 5:00 am and sunset near 7:00 pm—plenty of time to get out and explore. Mornings usually start clear, so they’re perfect for places like the Apartheid Museum, Constitution Hill, or nearby wildlife reserves.
Thunderstorms often roll in late in the afternoon. They’re usually brief, so you can plan indoor options like shopping at Sandton City Mall or checking out art galleries during those times.
The festive season brings lots of life to Johannesburg. You’ll find Christmas markets, outdoor concerts, and cultural festivals with local food, crafts, and music. Many restaurants and hotels roll out special holiday menus and events, too.
If you’re into nature, the rainfall creates lush green landscapes—December is a great time for the Johannesburg Botanical Gardens or a day trip to the Magaliesberg Mountains. Warm weather, cultural buzz, and all that greenery make December a really engaging time to experience the city.
Safety and Health Considerations
December in Johannesburg means strong sunshine and frequent afternoon storms. You’ll want to be ready for both intense UV rays and sudden heavy rain to stay comfortable and safe while you’re here.
UV Index and Sun Protection
December in Johannesburg brings a pretty high UV index. Sometimes, it gets so intense that you can end up with sunburn in just a few minutes.
Daytime highs usually hover around 27°C. Add those long daylight hours, and you’ve got a recipe for overexposure if you’re not careful.
Grab some broad-spectrum sunscreen (SPF 30 or higher) and remember to reapply every couple of hours. If you’re sweating or spending a lot of time outside, you’ll need to reapply even more often.
I’d recommend wearing lightweight, breathable cotton or linen clothes. They’ll help protect your skin and, honestly, they just feel better in the heat.
Don’t forget your sunglasses with UV protection. They’ll keep your eyes safe from glare and future problems. A wide-brimmed hat can also make a big difference, shading your face and neck.
If you’re planning to be outside, maybe aim for before 10 a.m. or after 4 p.m. The sun isn’t quite as harsh then.
Staying hydrated matters a lot. The mix of heat and strong sunlight can really sneak up on you and cause dehydration if you’re not drinking enough water.
Carry a refillable bottle. Try not to overdo it with alcohol or caffeine, since those can make you lose even more fluids.
Staying Safe During Storms
December in Johannesburg? It’s usually the wettest month, with about 140 mm of rainfall and roughly 14 rainy days. Afternoon thunderstorms pop up often. These storms can hit hard with heavy rain, lightning, and short bursts of strong wind.
When a storm rolls in, steer clear of open fields, tall trees, and anything metal. Lightning loves those. If you’re driving, just pull over somewhere safe, then wait out the worst of it, because the roads can flood before you know it.
A compact umbrella or a light rain jacket comes in handy, but honestly, waterproof shoes or sandals that dry fast make life easier when showers happen all the time. I’d suggest tossing your electronics and valuables in waterproof bags, too, just in case.
Severe storms sometimes knock out the power, so keep a flashlight nearby, especially if you’re staying somewhere that loses electricity a lot. A little planning goes a long way when the weather turns wild.