I see in Colby Cosh there is a frost warning for Edmonton.
Let's take a look at Accuweather. They are still not copping to overnight frost, but in September so far they show highs and lows at or below the 30-year average until yesterday, Sept. 5: then yesterday: high slightly above average, low slightly below. For today they predict a high just above average, and a low tied at the average of 7. Where did the frost warning come from?
For the rest of the month (actually Sept. 7-Oct. 6): taking above or below to be a difference of two or more degrees: 12 high's are forecast to be above average, 8 below, the rest tied (or within one degree). 11 low's are forecast to be above average, 9 below, the rest tied. The month is forecast to be slightly above average. But then, the forecast seems to be running warm, doesn't it?