Thonon-les-Bains experiences a continental climate with cold winters and warm summers. Winters, from January to March, are chilly with temperatures often below freezing, averaging around 0°C. Spring arrives in April and May, bringing mild temperatures, with highs occasionally reaching up to 24°C. Summer months, June to August, are warm to hot, with average highs around 15-16°C, but occasional heatwaves can push temperatures above 30°C. Autumn, from September to November, sees a return to cooler temperatures, often below 0°C, before the cold winter sets in again.