Chilliwack (Roger Pannett/Environment Canada) – During the first week of December an upper level ridge of high pressure produced welcome clear, sunny and mild conditions. For the remainder of the month an unrelenting storm track, aimed at B.C., resulted in predominantly mild, rainy weather.
Three record high temperatures occurred: –
Date New Record Previous Record
December 8th. High Minimum 7.7 ⁰C (+7.7 ⁰C) 7.0 ⁰C in 2015.
December 19th. High Mean 9.45 ⁰C (+6.75 ⁰C) 9.3 ⁰C in 2004.
December 19th. High Maximum 13.4 ⁰C (+8.1 ⁰C) 11.9 ⁰C in 2004.
(Peak temperature for the month.)
With the arrival of the winter season on December 21st, abundant moisture associated with a deepening Pacific low-pressure system, moving across Washington state, transitioned into heavy wet snow. Just in time for Christmas,
‘Let it snow! Let It snow! Let it snow!’ The 31.2 cm snowfall was the snowiest December day since the 31.8 cm snow fall on December 10th, 2016.
The 13 cm of residual snow on the ground assured a White Christmas. (The most snow since the 33-37 cm on Christmas Day 2008.)
On December 23rd, beneath clear overnight skies, temperatures fell to the low for the month at -2.3 ⁰C the first killing frost of the season.
Prior to months end, mild rainy conditions returned as another series of Pacific frontal systems moved onshore.
With mean temperatures 1.76 ⁰C above normal it was the 14th consecutive month with above normal mean temperatures.
With total precipitation >21% below normal, including snowfall at > 10 % below normal, it was the 22nd consecutive December with precipitation totals below average.
CITY OF CHILLIWACK WEATHER REPORT
Data recorded by Roger Pannett, Volunteer Weather Observer for Environment Canada at Chilliwack, B.C.
|Variable||December 2020||30 Year Average|
|Mean Maximum||7.59 C||6.2 C|
|Mean Minimum||2.53 C||0.4 C|
|Mean Temperature||5.06 C||3.3 C|
|Rainfall||200.7 mm||259.6 mm|
|Snowfall||31.2 cm||34.8 cm|
|Total Precipitation||231.9 mm||294.4 mm|
|Days of Rain||20 days||18 days|
|Days of Snow||1 day||5 days|
|Total Days of Precipitation||20 days||22 days|
|Relative humidity average||81.84 %||.|