Planning for the weather is an important factor for making your trip to Hayden Lake a success, especially when you're splurging. The hottest months are usually July and August, with an average temperature of 19°C, while the coldest months are January and February, with an average of -1°C. The snowiest months in Hayden Lake are January, December, March and February, with each month seeing an average of 20 cm of snowfall.