There's nothing like an all-inclusive holiday in Big Sand Lake to revive you, especially when you know what kind of weather to expect. Here's some information to help you choose when to book: The hottest months are usually July and August, with an average temperature of 14°C, while the coldest months are February and January, with an average of -18°C. February and December are the driest months, while July and August are the rainiest months.