Weather is probably a major factor when you plan your trip to Glarus, but bear in mind that cheaper options are usually available when the weather isn't as good. The hottest months are usually August and July, with an average temperature of 8°C, while the coldest months are January and February, with an average of -7°C. The rainiest months in Glarus are August, June, July and May, with each month seeing an average of 325 mm of rainfall.