Mt Kilimanjaro is big. In fact, it is so big that it changes the climate around itself and has its own weather system.
Kilimanjaro, in terms of weather, is a huge obstruction to the trade winds that bring along rains.
When moisture laden winds encounter an obstruction, there are two ways they can go - around the obstruction or over it. It is usually a combination of both.
Mt Kilimanjaro, however, is so big that it forces these winds to go higher, which results in them cooling. These form the basis of rain or snow on and around the mountain. These patterns are studied in detail by scientists and, interestingly, paragliders.
Due to the location and topography of Tanzania, the seasonal trade winds that collide with the mountain follow the following pattern:
- End March to May - The South-East trade winds that travel long distances over the Indian Ocean. These collide with Mt. Kilimanjaro, their first major obstacle, results in heavy rains on the southern side of the mountain. This leads to the season known as the Long Rains, which is the main rainy season on Kilimanjaro. An interesting consequence of this is the lush forest cover found on the southern slopes
- June to October - Dry winds from the north-east hit the mountain during these months. They effectively ensure that the weather is dry (yet cold) as they are strong winds. This is the peak season for trekking Kilimanjaro and a safari in Tanzania
- November to mid-December - The same winds from the north-east, which have already lost much moisture traveling over the African landmass, result in the Short Rains. The rains are usually concentrated on the Northern end of Kilimanjaro. These are much less intense, as is reflected by the comparison of vegetation on the northern and southern sides of Mt Kili.
- Late December to February - As the winds recede, the rains gradually withdraw and this leads to a second, dry period during these months.
These are the general conditions that lead to the weather conditions on Kilimanjaro, but in reality, the weather here is quite unpredictable. You may find weeks in April, where it doesn’t rain. Or a lowering of pressure may force the cloud cover higher, resulting in rains (or snowfall) on the upper reaches of the mountain.
Table: temperature, precipitation & number of visitors per month
|Month||Temperature (°C)||Precipitation (mm)||Number of visitors|