Johannesburg Monthly Rainfall & Precipitation

This page shows both the average monthly rainfall and the number of rainy days in Johannesburg, Gauteng, South Africa. This average is based on long-term data collected between 1990 and 2020. Let's now guide you through the details for a complete overview.

Generally, Johannesburg receives mid-range precipitation levels, with 779 mm (31 in) annually. The distribution varies significantly throughout the year, with a distinct dry season during certain months, as shown in our charts below.

Monthly Precipitation Levels

The average number of days each month with precipitation (> 0.2 mm (0.01 in))

The climate in Johannesburg shows significant variation throughout the year. Expect 140 mm (5.5 in) of precipitation during the wettest month December, distributed over 14 rainy days.

In contrast, July offers drier and sunnier days, with around 3.6 mm (0.1 in) of rainfall over a single rainy day.

December, the wettest month, has a maximum daytime temperature of 27°C (81°F). The city receives 264 hours of sunshine in this period. During the driest month July you can expect a temperature of 20°C (68°F). For more detailed insights into the city's temperatures, visit our Johannesburg Temperature page.

Johannesburg's average annual precipitation is 779 mm (31 in). Let's compare this to some popular worldwide tourist destinations:

In Barcelona, Spain, the average annual precipitation is 620 mm (24 in), evenly distributed across the year with no extreme wet or dry seasons.

Osaka, Japan, experiences 1507 mm (59 in) of rainfall annually, spread across the year with wetter summers.

Adelaide, Australia, enjoys 511 mm (20 in) of annual precipitation, with dry summers and wet winters.

Mumbai, India, experiences a tropical monsoon climate with 1860 mm (73 in) of annual rainfall, with the majority of precipitation happening during the monsoon season from June to September.

Precipitation amounts are measured using specific gauges installed at weather stations, collecting both rain and snow and any other type of precipitation. Rainfall is measured directly in millimeters, while that from snow and ice is obtained by melting it. Automated systems often incorporate heaters to make this easier.

Information from these stations is transmitted via Wi-Fi, satellite, GPS, or telephone connections to central monitoring networks. This information is immediately updated and integrated into weather models and forecasts.

Precipitation has a very strong role in determining the local climate and ecosystem:

• Changing Rainfall Patterns: Global warming causes drastic changes in the patterns of rainfall. Some areas have been experiencing increased frequency and intensity of rainfall, while other areas experience longer dry spells or even droughts.
• Local Impacts: Many regions are experiencing heavier rainfall in the winter months and drier, hotter summers. This affects agriculture, water resources, and ecosystems.

• Mawsynram in India is noted as being the wettest place on earth, with over 11 meters (36 feet) of rain falling every year.
• In contrast, Antofagasta in Chile is among the driest places on the planet, getting less than 0.1mm (0.004 inches) per year, with some years recording virtually no rainfall.
• Nearly 1,650 thunderstorm cells are estimated over the planet at any given time.

For more detailed information about Johannesburg's weather, including sunshine hours, humidity levels, and temperature data, visit our Johannesburg Climate page.