Dumont 7 Day Weather. 1  Wednesday:The Dumont forecast for Mar 29 is 51 degrees and Sunny. There is 61 percentage chance of rain and 12 mph winds from the North-Northwest. 2  Thursday:The Dumont forecast for Mar 30 is 47 degrees and Sunny. There is 44 percentage chance of rain and 6 mph winds from the North-Northeast.