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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 17th, 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 9th, Mother’s Day, beneath clear overnight skies, temperatures fell to a cool 4.5 ⁰C, (2.3 ⁰C below normal.) On May 31st, 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 10th consecutive May with temperatures above normal. A trend never previously observed since Chilliwack temperature records commenced in 1895.

For the 11th 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 3rd driest on record. 1912 March to May, 122.2 mm

1924 “ “ “ ,146.1 mm

2021 “ “ “ ,174.9 mm

On May 31st, 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.

VariableMay 202130 Year Average
Mean Maximum20.13 C18.4 C
Mean Minimum9.12 C7.6 C
Mean Temperature14.63 C13.0 C
Rainfall41.2 mm98.3 mm
Snowfall0.0 cm0.0 cm
Total Precipitation41.2 mm98.3mm
Days of Rain12 days12 days
Days of Snow
Total Days of Precipitation12 days12 days
Relative humidity average65.19 %.

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