May in Johannesburg averages a daily high of 20.1°C with nights around 7.7°C. Expect roughly 4 wet days totalling 26.1mm. Comfortable conditions for being outdoors all day.
Across the year, the best time to visit Johannesburg is April–September.
Based on JOHANNESBURG INTERNATIONAL, SF (21.4km), 1995–2024. 17 years of May data.