First week of fall in Calgary set for above seasonal temperatures

The calendar flips from summer to fall Monday, but the mercury isn’t exactly getting the message.

Although Sept. 22 marks the start of astronomical fall — the fall equinox — Janelle Gergely, a meteorologist with Environment and Climate Change Canada (ECCC) explains that meteorologists use a different measurement when looking at the change in seasons.

“We actually use a different equinox from meteorology; so meteorological fall is Sept. 1 to Nov. 30 and that’s different than this fall equinox,” she said. “The fall equinox is based on the Earth’s orbit and tilt towards the sun and it’s when day and night are generally around the same length. So, meteorological fall actually started about three weeks ago versus astronomical fall, which starts today.”

With that in mind, it almost makes the weather of the last few weeks even more unusual; after a rather cold and rainy June and July, the end of August and most of September have been quite dry and hot.

ECCC says the average high for this time of year is 16 C.

But, every day this week is forecast to surpass that; the weather agency says Monday will see a high of 20 C, Tuesday a scorching 27 C, and Wednesday a bit cooler at 18 C.

The second half of the week will be much of the same — the forecast high for Thursday is 22 C, Friday and Saturday could reach 19 C, and Sunday will be a nice 21 C.

Overnight lows will dip to single digits for most of the week but stay far from the freezing point of 0 C.

However, Gergely says Calgarians with plants still in the ground might want to take some extra steps.

“Anything 4 C or below, if you see that in the forecast, you might want to consider covering your plants, especially if there’s no cloud cover out,” she explained. “We can lose a lot of long wave radiation and the temperatures can cool quite quickly, and then you’d be at risk of frost.”