The main rainy season lasts from the end of March all the way to mid-June. It is impossible to predict when the rains will begin and when they will come to a stop, just like it is everywhere else. This period is the warmest time of the year in Tanzania, but most operators do not offer climbs in April/May because these months are also very wet.
The rain slowly decreases, and the temperatures on Kilimanjaro do the same. The weather on Kilimanjaro is fairly dry and clear but the nights are usually bitter cold. June is quiet, but the number of climbers increases as the year progresses.
August and September are the peak climbing season on Kilimanjaro. The weather is great with clear days and warmer nights compared to June/July. However, you may get clods blanketing the forest/moorland zone, and on the southern routes, there could be some rain on the first days of the climb. However, once you’ve left the rain forest behind, the climb is clearer from then on. The good conditions go on until October when the short rains are expected to begin.
The weather on Kilimanjaro begins to become unstable and the number of people climbing drops. There are afternoon clods and occasional thunderstorms just like in any tropical regions of the world when the rainy season is approaching. As long as you can withstand the occasional showers, you shouldn’t have any problems climbing at this time of the year.
This is usually the small rainy season. The temperatures drop, and the rains begin making it hard to climb the mountain at this time.
The period around Christmas and new years is the second peak climbing season on Kilimanjaro. Traffic is usually high even though there is a good chance of rainfall and thick clouds in the lower regions. It is not a great time to climb the mountain.
Mid-January to mid-March is a good time to climb Kilimanjaro. The weather is reasonable, not too cold or too wet, and the climbers are not too many. The days are beautiful, clear and dry with occasional brief showers. The chances of rain gradually increase as you approach the long rainy season in March.
There are a few more things worth taking notes about the weather on Kilimanjaro.
Whether you want to avoid the main rush or that’s the only time you can get away from work, you can climb the mountain at a less than perfect time of the year. If this is the case, the Rongai route is the best route for you because the northern side is much drier that the other routes.
If you want the best weather on Kilimanjaro but the crowds are not welcome for you, you can pick Rongai route, Shira and Lemosho other than the crowded Machame and Marangu routes.
The temperatures are something you should put into consideration. People in pictures without hats or gloves, wearing short sleeves on the summit are a misrepresentation of the weather on Kilimanjaro. The day and night temperatures can be vastly different. In that respect, the alpine desert is no different from other deserts in the world. Above 4000m (13000 ft) a sunny day may be above 30°C (85F), the nights are still below zero.
So how cold is it on the summit? Or during the night climb, how cold is it? The temperatures can drop to -20°C (-5F), but you should know that with the additional chill factor of wind the felt temperature might be as low as -40. Be prepared for the worst and enjoy everything that turns out to be easier than expected.