A thunderstorm with lightning lit up the skies on Sept. 7 across the Fraser Valley. (Jaimie Grafstrom photo)

A thunderstorm with lightning lit up the skies on Sept. 7 across the Fraser Valley. (Jaimie Grafstrom photo)

September in Chilliwack was quite a bit rainier than normal

It was the thunderstorm of Sept. 7 that ushered in three weeks of the wet stuff

Wet was the word.

The month of September saw rainfall that was more than 44 per cent above normal in Chilliwack, according to Roger Pannett, local volunteer weather observer for Environment Canada.

But with a ridge of high pressure that moved into the southern half of B.C., the first week of September was predominantly sunny and very warm.

WATCH: Lightning struck repeatedly in Sept. 7 storm

It was “atmospheric instability” that produced a thunderstorm on Sept. 3 but rainfall was light with at 0.6 mm.

But on Sept. 7, a volatile and unstable air mass moving northwards from Washington State, produced an unusually severe thunderstorm with a fearsome display of lightning and heavy rain totalling 22 mm.

“The storm ushered in three weeks of generally wet and unsettled conditions,” Pannett said in his report.

READ MORE: Teen lost beloved horse to lightning strike

A Pacific cold front moved in on Sept. 14, coupled with a strong southerly airflow, which directed abundant moisture into the Fraser Valley. The 32.5 mm rainfall exceeded the previous record for the day of 31.0 mm in 1920. Showery, unsettled conditions continued until near to months end before concluding with a cool air mass, with early season snow falls on the high mountain passes.

Total rainfall for the month was 44.9 above normal, the wettest September since the 167.8 mm in 2013.

The 2019 precipitation total to date is 841.5 mm on 103 days, compared to the 30-year average of 1160.5 mm on 117 days.

No temperature records were broken.

Temperature extremes for the month were a high of 30.2 C on September 5 and a low of 5 C on September 30. With the ongoing trend to above normal overnight temperatures, it was the fourth consecutive September with above normal mean temperatures.

During the summer of 2019, June to September, there were a total of 12 days with hot temperatures above 30 C., whereas the average is seven.

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Chilliwack Progress