Winters in Rennes are cool and temperate, with January being the coldest month, averaging around 6°C. As spring approaches, temperatures gradually warm up, reaching an average of 9°C by April, with occasional highs reaching up to 25°C. Summers are mild and pleasant, with June and July being the warmest months, often reaching highs of over 30°C. Autumn brings a return to cooler temperatures, with October averaging around 13°C before dropping again in winter.