The weather in Tonasket varies seasonally, but it's usually cold. The city is considered snowy for a total of 3.1 months out of the year. Average daily high temperatures are below 43 degrees. The coldest month is December, with a low of 23 degrees and high temperature of 32 degrees. The thin dotted line represents average perceived temperature. The climate of Tonasket varies from hot and humid to cold and dry.