Nouns ending in -at are masculine.
The suffix often marks a status or condition.
Is climat masculine or feminine?
leclimat
The rule behind it
100% of -at nouns are masculine
In context
Un climat humide est caractéristique de la péninsule.
A humid climate is characteristic of the peninsula.
Il s'habituera bientôt au climat d'ici.
He will soon get used to the climate here.
Londres diffère de Tokyo en termes de climat.
London is different from Tokyo climatically.