Planning for the weather is a good way to make your trip to St Gilles-les-Bains relaxing and enjoyable, especially when you're splurging. The hottest months are usually February and January, with an average temperature of 25°C, while the coldest months are August and July, with an average of 20°C. The rainiest months in St Gilles-les-Bains are January, February, March and December, with each month seeing an average of 257 mm of rainfall.