Swaziland has a subtropical climate with wet, hot summers (approximately 75% of annual rainfall occurs from October to March) and cold dry winters (April-September). Swaziland lies at the transition lines of major climatic zones, being influenced by air masses from different origins, such as equatorial convergence zone (summer rains), subtropical eastern continental moist maritime (onshore flow with occasional cyclones), dry continental tropical and marine west Mediterranean (winter rains, with rare snow). The country’s agro-ecological zones result in differentiated climatic conditions across its diverse topography and ecosystems, ranging from sub-humid and temperate in the highvelds to semi-arid and warm in the lowvelds. Key historical climate trends are summarized below:
- Mean annual temperature varies from 17°C in the highlands to 22°C in the Lowveld.
- Highest January mean maximum temperatures are recorded in the Eastern Lowveld (34°C at Lavumisa) and lowest in the Highveld (22°C at Usutu).
- The lowveld tends to be much hotter during the day, recording about 40°C at times and much cooler at night with minimum temperature close to zero.
- Mean annual rainfall ranges from about 1,500 mm in the northern Highveld to 500mm in the southern lowland.
- The rainiest periods for the country tend to occur in November to February, overlapping with the typically hottest period.
- The driest zone in Swaziland is the moist semi-arid zone, found in the southern Lowveld. The intermediate dry sub-humid zone occurs mainly in the northern Lowveld. The most humid part of the Drylands covers the Lower Middleveld, most of the Lebombo and a small part of the Upper Middleveld.
This section provides the options to visualize historical climate data for different timeframes via map and annual cycle chart.