Avg High
Johannesburg South in December
Avg Low
Rain
Daylight
14h
What to expect
December in Johannesburg South is early summer, with a settled seasonal pattern already in place. The month is warm and inviting for long walks, with a noticeable cool-down after sunset. Most days feel close to what the averages suggest, with straightforward pacing. There is plenty of daylight to stretch outdoor time.
December in context
How it compares to the rest of the year in Johannesburg South.
Hottest (avg)
#2 / 12
Wettest (avg)
#1 / 12
Daylight Hours
#1 / 12
Windiest (avg)
#5 / 12
Highest UV
#2 / 12
Most Humid
#4 / 12
Monthly climate breakdown
Temperature
- Daytime high
-
- Nighttime low
-
- Feels like (avg)
-
Sunshine
- Daylight hours
- 13.8 h
- UV index (max)
- 10
- Typical sun hours
- 05:10 - 18:55
Rain & Snow
- Total rain
-
- Rainy days
- 21 days
- Cloud cover (avg)
- 55%
Humidity & Wind
- Humidity (avg)
- 69%
- Wind (avg)
-
- Wind (max gusts)
-
Daily climate explorer
Day 15 selected for December. Typical high 24.8°C and low 14.4°C.
Typical disruptions in December
Based on 30 years of historical data, these are the disruption patterns most likely to affect plans in December.
Rain High impact
Rain disruption Measures: Likely rain disruption days. Observed about 27% of days (8.5 days/month) in December. Historical risk signal only, not a day-by-day forecast.
8.5 days / month
~27% of days
Why this matters
- Expected days 8.5 days / month
- Probability ~27% of days
- Intensity Up to ~28mm (P95)
Rain disruption risk appears on ~8 days. Outdoor plans can become unreliable, so keep an indoor backup and flexibility around start times.
Rain High impact
Washout risk Measures: Washout day risk. Observed about 25% of days (7.8 days/month) in December. Historical risk signal only, not a day-by-day forecast.
7.8 days / month
~25% of days
Why this matters
- Expected days 7.8 days / month
- Probability ~25% of days
- Intensity Up to ~28mm (P95)
Washout conditions are possible on ~8 days. Outdoor plans can become unreliable, so keep an indoor backup and flexibility around start times.
Rain High impact
Heavy rain days Measures: Heavy rain days (>=10mm). Observed about 14% of days (4.2 days/month) in December. Historical risk signal only, not a day-by-day forecast.
4.2 days / month
~14% of days
Why this matters
- Expected days 4.2 days / month
- Probability ~14% of days
- Intensity Up to ~39mm (P95)
Heavy rain is possible on ~4 days. Outdoor plans can become unreliable, so keep an indoor backup and flexibility around start times.
Heat Moderate
Hot days Measures: Hot days (>=30C). Observed about 6% of days (1.9 days/month) in December. Historical risk signal only, not a day-by-day forecast.
1.9 days / month
~6% of days
Why this matters
- Expected days 1.9 days / month
- Probability ~6% of days
- Intensity Up to ~34°C (P95)
Hot days are possible on ~2 days. Midday activity often needs adjustment around shade, hydration, and indoor fallback options.
Visibility Minor
Fog-likely signal Measures: Fog-likely visibility proxy. Observed about 2% of days (0.7 days/month) in December. Historical risk signal only, not a day-by-day forecast.
0.7 days / month
~2% of days
Why this matters
- Expected days 0.7 days / month
- Probability ~2% of days
- Intensity Up to ~95% (P95)
Fog-likely conditions are possible on ~1 days. Fixed-time outdoor plans are safer with a backup option and flexible timing.
Show all disruptions (16 more)
Rain High impact
Washout run Measures: Multi-day washout runs. Observed about 1.9 days/month in December. Historical risk signal only, not a day-by-day forecast.
1.9 days / month
Probability unavailable
Why this matters
- Expected days 1.9 days / month
- Probability —
- Intensity Up to ~29mm (P95)
Multi-day washout runs are possible on ~2 days. Outdoor plans can become unreliable, so keep an indoor backup and flexibility around start times.
Rain High impact
Very heavy rain Measures: Very heavy rain days (>=25mm). Observed about 2% of days (0.7 days/month) in December. Historical risk signal only, not a day-by-day forecast.
0.7 days / month
~2% of days
Why this matters
- Expected days 0.7 days / month
- Probability ~2% of days
- Intensity Up to ~47mm (P95)
Very heavy rain is possible on ~1 days. Outdoor plans can become unreliable, so keep an indoor backup and flexibility around start times.
Wind High impact
Strong gusts Measures: Strong gust days (>=60 km/h). Observed about 1% of days (0.5 days/month) in December. Historical risk signal only, not a day-by-day forecast.
0.5 days / month
~1% of days
Why this matters
- Expected days 0.5 days / month
- Probability ~1% of days
- Intensity Up to ~70km/h (P95)
Strong gusts are possible on ~0 days. Exposed activities and transport links are more likely to be disrupted, so keep sheltered alternatives ready.
Wind High impact
Stormy conditions Measures: Storm-impact proxy days. Observed about 1% of days (0.3 days/month) in December. Historical risk signal only, not a day-by-day forecast.
0.3 days / month
~1% of days
Why this matters
- Expected days 0.3 days / month
- Probability ~1% of days
- Intensity Up to ~66km/h (P95)
Stormy conditions are possible on ~0 days. Exposed activities and transport links are more likely to be disrupted, so keep sheltered alternatives ready.
Heat Moderate
Hot feels-like days Measures: Hot feels-like days (>=32C). Observed about 2% of days (0.5 days/month) in December. Historical risk signal only, not a day-by-day forecast.
0.5 days / month
~2% of days
Why this matters
- Expected days 0.5 days / month
- Probability ~2% of days
- Intensity Up to ~34°C (P95)
Feels-like heat >=32C is possible on ~0 days. Midday activity often needs adjustment around shade, hydration, and indoor fallback options.
Cold Moderate
Cold feels-like nights Measures: Cold feels-like nights (min <=5C). Observed about 1% of days (0.2 days/month) in December. Historical risk signal only, not a day-by-day forecast.
0.2 days / month
~1% of days
Why this matters
- Expected days 0.2 days / month
- Probability ~1% of days
- Intensity Up to ~4°C (P95)
Cold feels-like nights are possible on ~0 days. Long outdoor blocks become harder to sustain, so layer up and keep a warm indoor fallback nearby.
Rain Minor
Wet days Measures: Wet days (>=0.1mm). Observed about 77% of days (23.8 days/month) in December. Historical risk signal only, not a day-by-day forecast.
23.8 days / month
~77% of days
Why this matters
- Expected days 23.8 days / month
- Probability ~77% of days
- Intensity Up to ~19mm (P95)
Measurable rain is possible on ~24 days. Fixed-time outdoor plans are safer with a backup option and flexible timing.
Rain Minor
Rainy hours Measures: Rain-hours signal (>=3h rain). Observed about 61% of days (19.0 days/month) in December. Historical risk signal only, not a day-by-day forecast.
19.0 days / month
~61% of days
Why this matters
- Expected days 19.0 days / month
- Probability ~61% of days
- Intensity Up to ~18h (P95)
Several rainy hours are possible on ~19 days. Outdoor plans can become unreliable, so keep an indoor backup and flexibility around start times.
Cloud Minor
Cloudy days Measures: Cloudy days (cloud cover >=60%). Observed about 45% of days (14.0 days/month) in December. Historical risk signal only, not a day-by-day forecast.
14.0 days / month
~45% of days
Why this matters
- Expected days 14.0 days / month
- Probability ~45% of days
- Intensity Up to ~99% (P95)
Cloudy skies are possible on ~14 days. Fixed-time outdoor plans are safer with a backup option and flexible timing.
Wind Minor
Gusty days Measures: Gusty days (>=40 km/h). Observed about 39% of days (12.0 days/month) in December. Historical risk signal only, not a day-by-day forecast.
12.0 days / month
~39% of days
Why this matters
- Expected days 12.0 days / month
- Probability ~39% of days
- Intensity Up to ~57km/h (P95)
Gusty conditions are possible on ~12 days. Exposed activities and transport links are more likely to be disrupted, so keep sheltered alternatives ready.
Rain Minor
Wet most of day Measures: Wet-most-of-day signal (>=6h rain). Observed about 39% of days (12.0 days/month) in December. Historical risk signal only, not a day-by-day forecast.
12.0 days / month
~39% of days
Why this matters
- Expected days 12.0 days / month
- Probability ~39% of days
- Intensity Up to ~20h (P95)
Wet-most-of-day conditions are possible on ~12 days. Outdoor plans can become unreliable, so keep an indoor backup and flexibility around start times.
Humidity Minor
High humidity Measures: High humidity days (RH >=80%). Observed about 22% of days (6.8 days/month) in December. Historical risk signal only, not a day-by-day forecast.
6.8 days / month
~22% of days
Why this matters
- Expected days 6.8 days / month
- Probability ~22% of days
- Intensity Up to ~92% (P95)
High humidity is possible on ~7 days. Comfort and pace can drop quickly, so plan shorter outdoor blocks with air-conditioned backup stops.
Cloud Minor
Mostly cloudy days Measures: Mostly cloudy days (cloud cover >=80%). Observed about 21% of days (6.6 days/month) in December. Historical risk signal only, not a day-by-day forecast.
6.6 days / month
~21% of days
Why this matters
- Expected days 6.6 days / month
- Probability ~21% of days
- Intensity Up to ~100% (P95)
Mostly cloudy skies are possible on ~7 days. Fixed-time outdoor plans are safer with a backup option and flexible timing.
Cloud Minor
Overcast days Measures: Overcast days (cloud cover >=95%). Observed about 8% of days (2.5 days/month) in December. Historical risk signal only, not a day-by-day forecast.
2.5 days / month
~8% of days
Why this matters
- Expected days 2.5 days / month
- Probability ~8% of days
- Intensity Up to ~100% (P95)
Overcast skies are possible on ~2 days. Fixed-time outdoor plans are safer with a backup option and flexible timing.
Other Minor
Low visibility proxy: same as fog-likely (RH ≥90% AND cloud ≥95%) — true visibility requires hourly visibility data Measures: Low visibility proxy: same as fog-likely (RH ≥90% AND cloud ≥95%) — true visibility requires hourly visibility data. Observed about 2% of days (0.7 days/month) in December. Historical risk signal only, not a day-by-day forecast.
0.7 days / month
~2% of days
Why this matters
- Expected days 0.7 days / month
- Probability ~2% of days
- Intensity Up to ~95 (P95)
Low visibility proxy: same as fog-likely (RH ≥90% AND cloud ≥95%) — true visibility requires hourly visibility data is possible on ~1 days. Fixed-time outdoor plans are safer with a backup option and flexible timing.
Heat Minor
Heatwave run Measures: Heatwave runs (>=3 hot days). Observed about 0.3 days/month in December. Historical risk signal only, not a day-by-day forecast.
0.3 days / month
Probability unavailable
Why this matters
- Expected days 0.3 days / month
- Probability —
- Intensity Up to ~34°C (P95)
Heatwave runs are possible on ~0 days. Midday activity often needs adjustment around shade, hydration, and indoor fallback options.
Frequently asked questions
Is December a good time to visit Johannesburg South?
Typical December days in Johannesburg South reach highs of 25°C (77°F) with nights around 14°C (57°F). It usually feels warm by day and cool after dark. It is among the wetter months, so it is wise to have some indoor backup plans or flexible activities.
What are temperatures like in December?
Daytime temperatures in December typically peak near 25°C (77°F), while nights drop to around 14°C (57°F). Expect warm afternoons and cool evenings.
How much does it rain in December?
Rainfall in December averages 132 mm (5.2 in) across roughly 21 days. Overall it is a very wet time of year, so a light rain jacket and waterproof shoes are very handy.
How many hours of daylight are there in December?
You can expect about 14 hours of daylight in December. Sunrise is typically around 05:10 and sunset near 18:55. You get long days with comfortable amounts of daylight.
How strong is the sun in December?
UV levels frequently reach very high levels (around 10), so strong sun protection is essential, especially around midday.
Is it windy in December?
In December, average wind speeds are around 11 km/h (7 mph), with gusts on the windiest days reaching about 50 km/h (31 mph). On the ground, it is it often feels breezy, especially in more exposed spots or along the coast.