Weather will likely play an important role when you plan your trip to Brønnøy, but bear in mind that cheaper options are usually available when the weather isn't as good. The hottest months are usually July and August, with an average temperature of 12°C, while the coldest months are February and January, with an average of -1°C. The rainiest months in Brønnøy are September, October, March and December, with each month seeing an average of 212 mm of rainfall.