Johannesburg records about 713mm of rain across roughly 79 wet days a year, which is a 22% chance on an average day. January is the wettest month at 125mm (18% of the annual total) and July the driest at 4mm. Local rain type: thunderstorms. Joburg summers bring dramatic afternoon thunderstorms — usually between 3-5 PM, intense but brief. Winter is bone-dry.
Chance of rain on an average day: 22%
Rainfall climatology for Johannesburg. The live hour-by-hour answer for today loads at the top of this page from Open-Meteo and refreshes through the day — the figures below describe a typical year, not today.
Last updated: · Live forecast data refreshes hourly.
| Annual rainfall | 713mm |
| Rain days per year | 79 |
| Odds on an average day | 22% |
| Wettest month | January — 125mm over 14 days |
| Driest month | July — 4mm over 1 days |
| Rain type | thunderstorms |
| Best dry window | May through September offers dry, sunny winter weather — Joburg's high altitude keeps days warm and crisp. |
| Worst rain window | December and January bring the most intense thunderstorms with frequent lightning. |
January delivers 3025% more rain than July (125mm vs 4mm). That gap is the difference between planning around showers and ignoring them.
No single month holds more than 18% of the annual total, so rain in Johannesburg is spread through the year — there is no season you can rely on being dry.
Johannesburg rain arrives in short, heavy bursts — shelter and timing matter more than gear.
Rain falls on about 14 days in January against 1 in July — the frequency swing matters more for planning than the millimetre totals.
Climate normals. Use them to judge whether today's live forecast at the top of the page is typical or unusual for the season.
| Month | Rainfall | Rain days | Chance on a given day | Highs |
|---|---|---|---|---|
| January | 125mm | 14 | 47% | 26°C |
| February | 90mm | 10 | 33% | 26°C |
| March | 91mm | 10 | 33% | 25°C |
| April | 54mm | 6 | 20% | 23°C |
| May | 13mm | 1 | 3% | 20°C |
| June | 9mm | 1 | 3% | 18°C |
| July | 4mm | 1 | 3% | 17°C |
| August | 6mm | 1 | 3% | 17°C |
| September | 27mm | 3 | 10% | 18°C |
| October | 72mm | 8 | 27% | 20°C |
| November | 117mm | 13 | 43% | 23°C |
| December | 105mm | 12 | 40% | 25°C |
Rain probability is the chance that at least 0.2mm falls at your location — not how long it rains. For Johannesburg we combine the hourly probability curve, expected volume in millimetres, and the city's own rainfall record into a single umbrella verdict.
| Factor | Weight | What it measures |
|---|---|---|
| Hourly probability | 40% | Peak and sustained chance of measurable rain across the next 24 hours. |
| Expected volume | 30% | Total millimetres, which separates a passing shower from a genuine soaking. |
| Timing & duration | 20% | When rain starts, when it eases, and the longest continuous dry window. |
| Local rain type | 10% | Drizzle, brief showers, thunderstorms or monsoon — each needs different gear. |
Live hourly values come from Open-Meteo and refresh through the day. Monthly rainfall figures are climate normals, so they describe a typical year rather than a forecast.
Johannesburg records rain on roughly 79 days a year — about a 22% chance on any given day — totalling around 713mm.
January, with about 125mm over 14 rain days. That is 18% of the entire year's rainfall in a single month.
July is the driest month at 4mm across roughly 1 days. May through September offers dry, sunny winter weather — Joburg's high altitude keeps days warm and crisp.
Joburg summers bring dramatic afternoon thunderstorms — usually between 3-5 PM, intense but brief. Winter is bone-dry.
No. Probability is the chance that at least 0.2mm of rain falls at your location at some point in the period. Check the expected millimetres alongside it: 40% with 0.4mm is a passing shower, 40% with 12mm is a soaking.