Durant la saison des pluies, il pleut tellement qu'il est difficile de planifier des sorties.

English Translation

During the rainy season, it rains so much that it is difficult to plan outings.

Can I use “pendant” here as well?

You would be understood if you did, but “durant” feels natural/right.

I think this is because we are talking about something that lasts the whole season, i.e a long period of time, uninterrupted.