Planning for the weather is an important factor for making your trip to Des Moines a success, especially when you’re splurging. The hottest months are usually August and July, with an average temperature of 18°C, while the coldest months are February and December, with an average of 5°C. The rainiest months in Des Moines are November, December, January and October, with each month seeing an average of 177 mm of rainfall.