I use 3 different sites to try and predict what our weather will be long term.
https://www.theweathernetwork.com/ca/weather/northwest-territories/yellowknife
http://www.accuweather.com/en/ca/yellowknife/x1a/weather-forecast/49534?p=accuweather
http://www.yr.no/place/Canada/Northwest_Territories/Yellowknife/
Yes I know the last one is in Norway, but they are pretty accurate most of the time.
I guess Norwegians have a lot of time to look at weather maps and stuff!!!