Johannesburg Rainfall & Precipitation: Monthly Averages and Year-Round Insights

This page shows the average amount of rainfall per month in Johannesburg. The numbers are calculated over a 30-year period to provide a reliable average. Now, let’s explore all the details to give you a full picture.

On average, Johannesburg receives a reasonable amount of rainfall, with an annual precipitation of 779 mm.

Monthly Precipitation Levels

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

Significant seasonal changes in precipitation occur throughout the year. During the wet season, December receives substantial rainfall, averaging 140 mm of precipitation, recorded across 14 rainy days.

In contrast, the drier season, July brings less rainfall, with 3.6 mm over a single rainy day.

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

Annual Precipitation in South Africa

The map below shows the annual precipitation across South Africa. You can also select the different months in case you are interested in a specific month.

Amsterdam Precipitation Compared World Wide

Johannesburg’s average annual precipitation is 779 mm. Let’s compare this to some popular worldwide tourist destinations:

Chicago, USA, sees an annual precipitation of 1062 mm, with rain and snow contributing to its humid climate.

Meanwhile, Buenos Aires, Argentina, enjoys a humid subtropical climate with 1000 mm of annual rainfall, mostly in the summer.

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

Ho Chi Minh City, Vietnam, receives 1955 mm of annual rainfall, with a pronounced wet season from May to November, typical of its tropical monsoon climate.

How is Precipitation Measured?

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.

Interesting weather facts

• "Ginger" was the longest-lasting Atlantic tropical storm, which spun around the open ocean for 28 days in 1971.
• The world's largest snowflake was recorded in the Guinness Book of Records, at 38 cm wide and 20 cm thick. The snowflake fell at Fort Keogh, Montana, USA, on 28 January 1887.
• The greatest snowfall recorded was on Mt. Rainier, Washington State, USA—over 31.5 meters fell during the winter of 1972.

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