Toulouse has a semi-continental climate with hot summers, mild winters, and more rainfall in spring and autumn than the Mediterranean resorts to the east. Spring (April–May) is the most pleasant time to visit: warm enough for café terraces, the plane trees along the Canal du Midi are freshly green, and the city is busy without being overwhelmed. The Festival Flamenco de Toulouse takes place in April and is one of the best flamenco events outside Spain.
Summer (June–August) is hot — often above 35°C in July — and the student population largely disappears, which makes the city quieter than you might expect. The Piano aux Jacobins festival brings classical concerts to the courtyard of the Couvent des Jacobins in September, when temperatures become pleasant again.
Autumn is excellent: harvest season means good food markets, the weather is warm through October, and crowds are thin. The Toulouse Game Show takes place in November.
Winter is mild compared to northern France — snow is rare — and the city functions normally. The Christmas market in Place du Capitole is modest but atmospheric. The ski resorts in the Pyrenees are operating from December, making Toulouse a useful base for a ski and city combination.