An Average May for Chilliwack – Weather Wise

Chilliwack (Roger Pannett Environment Canada) – To mid-month typical May weather conditions prevailed as a series of weak Pacific frontal systems moved through the Province. On May 17^th, the passage of an active cold front, with an associated upper level trough of low pressure, triggered thunderstorm activity, gusty winds and snow on the high mountain passes. Weather conditions remained unsettled and showery, until a building ridge of high pressure resulted in mostly sunny skies and warm temperatures during the last 3 days of the month.

On May 9^th, Mother’s Day, beneath clear overnight skies, temperatures fell to a cool 4.5 ⁰C, (2.3 ⁰C below normal.) On May 31^st, temperatures peaked at a warm 27.0⁰C, (7.0⁰C above normal) with a 32% relative humidity.

No temperature records occurred in May. However, with mean temperatures at 1.63 ⁰C above normal (standard deviation + or – 1.4 ⁰C) it was the 10^th consecutive May with temperatures above normal. A trend never previously observed since Chilliwack temperature records commenced in 1895.

For the 11^th consecutive month, precipitation was below normal. A trend never previously observed in the past >32 years. The March to May rainfall total was 56.34% below normal, the driest for the period in 97 years and the 3^rd driest on record. 1912 March to May, 122.2 mm

1924 “ “ “ ,146.1 mm

2021 “ “ “ ,174.9 mm

On May 31^st, the Fraser River at Mission had risen to 4.5 meters. Bank full is recorded as being at 5.49 meters.

The 2021 precipitation total to date is 510.1mm on 78 days compared to the average of 859.1 mm on 80 days.

Data recorded by Roger Pannett, Volunteer Weather Observer for Environment Canada at Chilliwack, B.C.