The Gleaner
Weather Report

Châteauguay Valley Weather September 19-25, 2021

Peter Finlayson, Ormstown Weatherman

September has kept pace with the warmer weather in the last week, a generally exceptional spell of mostly blue skies and pleasant temperatures. The average temperature stayed the same as the previous week at 17.3° C, while normal for the month is 16.2° C. Although the forecast for the last few days of September is for cooler weather during the day, the month should end up warmer overall.

The heat units have, as a consequence of the warm weather, continued to be above normal. There have now been 521 CHU so far in September, which is well above normal for the time of the month (prorated would be 474 CHU as the normal), and the month will no doubt surpass the 569 CHU that is the average for the period.

The season-to-date total is now 3270 CHU, with the start of the growing season measured from May 10th. This is just shy of the norm for heat units for the region, which is +/- 3300 CHU, with the rest of September and early October still to go. While monthly forecasts are notoriously unreliable, no weather in sight will produce a killing frost until the second half of October, as nighttime temperatures will be above average all month long.

There was a good drop of rain Thursday night and into Friday, adding 27 mm to the monthly total, which is still below average at 65 mm. At least we didn’t get the dumping delivered to south-western Ontario, where many communities received 60-90 mm – that’s a month’s worth of rain – in one day.

Despite the warm weather, the signs of fall are afoot as trees are slowly turning yellow, and the familiar honk of the geese can be heard overhead.

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