In Mali there are three types of climate: 1- the desert climate of the Sahara in the north, 2- the semi-desert climate of the Sahel in the centre, with a rainy season from June to September, and rainfall going from 100 to 600 millimetres (4 to 23.5 inches) per year, 3- the tropical climate of the savanna in the south, with a more intense and a bit longer rainy season (May and October), and rainfall exceeding 600 mm (23.5 in).

Precipitation in Mali

The vast northern area (zone 1 on the map), virtually lacking settlements except for a few rare oases, is occupied by the desert, and has an average temperature in January between 15 and 20 °C (59 and 68 °F), with some cold nights in the winter months (the cold records are around freezing), while in summer it's scorchingly hot.
In the extreme north-west, the climate is typical of the Sahara desert, July is the hottest month, and it almost never rains, although in the summer some cloud banks can pass and very few downpours can occur. Here are the average temperatures of Taoudenni.
Average temperatures - Taoudenni
Min (°C)111317202427292827231711
Max (°C)252932364044454341373126
Min (°F)525563687581848281736352
Max (°F)77849097104111113109106998879

More to the south, the temperature decreases slightly in July and August, because this area can more often be affected by a bit of cloudiness and some rare showers.
Here are the average temperatures of the northern city of Tessalit, located in the north-east, 500 metres (1,600 feet) above sea level.
Average temperatures - Tessalit
Min (°C)121418222528272626241914
Max (°C)273032374043424040373328
Min (°F)545764727782817979756657
Max (°F)81869099104109108104104999182

The cloudiness and the rare showers in the summer period are caused by the extreme offshoots of the African summer monsoon, so that damp winds move inland from the Atlantic Ocean, but up here they are not felt much.
Here is the average precipitation in Tessalit.
Average precipitation - Tessalit
Prec. (mm)10002515301510068

In Tessalit, the sun shines all year round, but in summer the hours of sunshine do not increase, or decrease slightly, even though the days are a bit longer.
Sunshine - Tessalit
Sun (hours)1010101110910991099

In the intermediate central area (zone 2), the climate becomes tropical, since the average temperature in January is equal to or higher than 20 °C (68 °F), while the hottest months of the year are April, May and June, when the maximum temperature normally exceeds 40 °C (104 °F), but with peaks of 47/48 °C (117/118 °F), because then the monsoon comes, which is able to lower the temperature by a few degrees, and to bring some downpours, more intense and frequent than in the northern area. This is the area called Sahel, which stretches from west to east, south of the Sahara.
In Timbuktu (or Tombouctou), the legendary city of the past Mali Empire, 180 mm (7 in) of rain per year fall, almost all from June to September, with a maximum of 75 mm (3 in) in August.
Here is the average precipitation.
Average precipitation - Timbuktu
Prec. (mm)1001515557530500183

After the rainy season, in which the temperature remains high, around 35/36 °C (95/97 °F), between September and October the heat increases slightly again, with highs around 37/38 °C (99/100 °F), but with peaks over 45 °C (113 °F), and then it decreases in the winter months, between 27 and 30 °C (81 and 86 °F). These are the only non-torrid months of the year, during which the sky is usually clear, even though a wind from the north-east often blows, the Harmattan, which raises dust and sand, making the sky whitish. What allowed the development of a flourishing city such as Timbuktu over the past centuries, has not been the moderate summer rainfall, but rather the great Niger River, whose headwaters are in the mountains of Guinea, and which passes in this semi-desert area, then bends and returns to the south.
Here are the average temperatures in Timbuktu.
Average temperatures - Timbuktu
Min (°C)131519232627262525231814
Max (°C)303337404242393738393530
Min (°F)555966737981797777736457
Max (°F)869199104108108102991001029586

In Timbuktu, the sun shines all year round, however in summer the hours of sunshine diminish slightly.
Sunshine - Timbuktu
Sun (hours)999898888998


Continuing south, the summer rains become more abundant. Already in Mopti, in the area of the "Inner Niger Delta", the rainfall amounts to 500 mm (20 in) per year.
In the southernmost area (zone 3), rainfall exceeds 600 mm (23.5 in) per year, and in the extreme south even 1,000 mm (40 in).
In the capital Bamako, the annual precipitation reaches 1,000 mm (40 in), and the rainy season becomes a little longer, with the first pre-monsoon showers already in May, a maximum of 300 mm (12 in) in August, and the last rains on early October.
Here is the average precipitation.
Average precipitation - Bamako
Prec. (mm)11220551302252901956551991

In the southern area, the maximum temperature is lower in the summer months, because of the cloud cover and the rains, so that it hovers around 30/32 °C (86/90 °F), while in winter the southern sun raises daytime temperatures to around 33 °C (91 °F), even though the air is dry and nights are quite cool. In Bamako, the hottest month is April, with highs around 40 °C (104 °F), because already in May the temperature drops a bit, under the blows of the first thunderstorms.
Average temperatures - Bamako
Min (°C)172023252524222222211817
Max (°C)333639403935323132353533
Min (°F)636873777775727272706463
Max (°F)919710210410295908890959591

In Bamako, the sunshine hours in summer diminish a bit more than in the central areas, and August is the least sunny month.
Sunshine - Bamako
Sun (hours)999877656787

When to go

The best time to visit Mali is winter, from December to February. In February, the heat rises and it starts to get hot in the south, while in January the sandstorms raised by the Harmattan begin to be more frequent in the north-central, so all in all the best month is December. However, in this season the nights can be cold in the north, where the temperature may drop near freezing at night, while in Bamako and in the south it can get to around 8/10 °C (46/50 °F).

What to pack

In winter: light clothes for the day, long and made of natural fabric (cotton or linen), desert turban for the wind-borne sand and dust, sunglasses (even graduated instead of contact lenses), a jacket and a sweater for the evening, desert boots or sandals, sweatshirt or sweater for boat trips on the Niger River.

In summer: for the desert, lightweight clothes, of natural fabric (cotton or linen), desert turban; a sweater for the night, sleeping bag to sleep outdoors. For Bamako and the south, light clothes, umbrella or light raincoat, possibly a sweatshirt for the rain showers.
For women, it is best to avoid shorts and miniskirts.