If you’re hoping to get lost in the rain on your romantic getaway, take a look at these details about year-round temperatures in Sandnes: The hottest months are usually August and July, with an average temperature of 14°C, while the coldest months are February and January, with an average of 4°C. The rainiest months in Sandnes are October, December, November and September, with each month seeing an average of 225 mm of rainfall.