In terms of weather, the best time of year to travel to Edmonton is Jun-Aug.  Summer temperatures in Edmonton are warm enough to enjoy the sunshine but not so warm that they are uncomfortable.  There is virtually no humidity in the area which means that the heat is a pleasant heat, even during the warmest months of July and August; the average high temperature for both months is 22°C (72°F), with temperatures overnight dropping to 12°C (52°F).

Early autumn can also be an excellent time to head to the area.  Although the nights can get chilly at this time (6°C or 43°F in Sept., 0°C or 32°F in Oct., the days are still nice (17°C/63°F in Sept.,  11°C / 52°F in Oct.). The beautiful changing colors of the trees in the area can make up for any nighttime weather discomfort.  Winter comes to the area relatively early in the year, with the first frost hitting the ground overnight in late September.  Snow begins sticking on the ground as early as the end of October or beginning of November.  It gets increasingly cold through the end of February and the snow stays on the ground until some time in April.  This may be good news for skiers who say that the best thing about the area is that there are several months of thick snowfall but the days themselves are generally sunny.

Environment Canada's Edmonton forecast page gives the current conditions and forecast, along with up-to-the-minute weather warnings. (If you are more comfortable with Fahrenheit and inches, you can see the same page in imperial units.)

Environment Canada also has a detailed page of information on Edmonton climate, with information on everything from temperature and precipitation, to windspeed and sunshine.