I think its too far to get an accurate forecast, confidence index is 2/5 ATM. The sites you can use as far as F is concerned are either Meteo France or accuweather.
Today:
https://meteofrance.com/previsions-m.../le-mans/72000
https://www.accuweather.com/fr/fr/le.../135975?page=1
As you say, slight disappointment on Sunday could happen (early hours). C'est bon pour les tomates et les salades as they say in Essex!