Botswana's climate is semi-arid. Though it is hot and dry for much of the year, there is a rainy season, which runs through the summer months. Rainfall tends to be erratic, unpredictable and highly regional. Often a heavy downpour may occur in one area while 10 or 15 kilometres away there is no rain at all. Showers are often followed by strong sunshine so that a good deal of the rainfall does not penetrate the ground but is lost to evaporation and transpiration.
'Pula', one of the most frequently heard words in Botswana, is not only the name of Botswana's currency, but also the Setswana word for rain. So much of what takes place in Botswana relies on this essential, frequently scarce commodity.
Seasons in Botswana
The summer season begins in November and ends in March. It usually brings very high temperatures. However, summer is also the rainy season, and cloud coverage and rain can cool things down considerably, although only usually for a short period of time.
The winter season begins in May and ends in August. This is also the dry season when virtually no rainfall occurs. Winter days are invariably sunny and cool to warm; however, evening and night temperatures can drop below freezing point in some areas, especially in the southwest.
The in-between periods - April/early May and September/October - still tend to be dry, but the days are cooler than in summer and the nights are warmer than in winter.
The rainy season is in the summer, with October and April being transitional months. January and February are generally regarded as the peak months. The mean annual rainfall varies from a maximum of over 650mm in the extreme northeast area of the Chobe District to a minimum of less than 250mm in the extreme southwest part of Kgalagadi District (see the map for districts). Almost all rainfall occurs during the summer months while the winter period accounts for less than 10 percent of the annual rainfall. Generally, rainfall decreases in amount and increases in variability the further west and south you go.
Summer days are hot, especially in the weeks that precede the coming of the cooling rains, and shade temperatures rise to the 38°C mark and higher, reaching a blistering 44°C on rare occasions. Winters are clear-skied and bone-dry, the air seductively warm during the daylight hours but, because there is no cloud cover, cold at night and in the early mornings. Sometimes bitterly so - frost is common and small quantities of water can freeze.
In summer during the morning period humidity ranges from 60 to 80% and drops to between 30 and 40% in the afternoon. In winter humidity is considerably less and can vary between 40 and 70% during the morning and fall to between 20 and 30% in the afternoon.
For tourists, the best visiting months are from April through to October - in terms of both weather and game viewing. It is during this period that the wildlife of the great spaces gather around what water there is - the natural waterholes and the borehole-fed dams - and are at their most visible.