Effective as of 12:00 AM Tuesday January 11 2022
View the latest severe weather warnings from BOM at http://www.bom.gov.au/wa/warnings/ .
Explanatory notes:
Becoming hot again today as the west coast trough deepens off the west coast. Becoming cooler again from Thursday as the west coast trough moves inland Wednesday afternoon.
Perth had seen the second hottest December on record with a mean maximum temperature of 31.7°C, drawing with 2020 and 1931 with the hottest December on record being December 2019 with a mean maximum temperature of 33.1°C.
While the severity of a heatwave is difficult as heatwave severity is a function of both intensity and duration and also on the humidity, minimum temperatures and cloud cover, the heatwave late during the month can be said to be Perth's worst on record for December and arguably the second worst on record for any month with the worst on record being the February 1933 heatwave.
During the heatwave, Perth saw some 4 consecutive days with a maximum temperature above 40°C which was the longest such spell on record for any month drawing with 4 consecutive days in February 2016 and February 1933.Perth has never seen 4 consecutive 40+°C days outside of February. The previous record longest 40+°C spell in December was 3 consecutive days in December 2019 and December 2020 where that was unheard of in December prior to December 2019.
In addition, it was also the hottest Christmas Day on record for any Australian capital city and perhaps for any major city in the world along with being Perth's third hottest December day on record with a maximum temperature of 42.8°C while Boxing Day was the second hottest December day on record with a maximum temperature of 43.5°C and hottest since Boxing Day 2007 which had a maximum temperature of 44.2°C.
Perth saw 6 consecutive days with a maximum temperature at or above 38°C which was the longest such spell for any month on record (draw) and previously unheard of in December.
Swanbourne, Rottnest Island and Mandurah saw their hottest December day on record on the 26th.
Pearce RAAF saw their highest December minimum temperature on record on the 26th whilst Swanbourne, Rottnest Island, Garden Island and Karnet saw their highest December minimum temperature on record on the 27th.
The heatwave was due to a very hot air mass lying over the region and the suppression of the sea breeze with the west coast trough having remained offshore for many days with a slow moving high in the Great Australian Bight where subsidence heating under and upper level anticyclone also contributed to the heat on both Christmas Day and Boxing Day.
On average Perth is hotter in February than in December where December's tend to be milder with fresh afternoon sea breezes, however, Perth has seen 3 consecutive December's whose mean maximum temperature is higher than the February average.
Maximum temperatures during this heatwave were:
December 24: 38.6°C
December 25: 42.8°C
December 26: 43.5°C
December 27: 41.0°C
December 28: 40.7°C
December 29: 38.6°C
The heatwave of February 1933 was arguably Perth's worst heatwave on record. That heatwave saw 4 consecutive 40+°C days which included 2 consecutive days with a maximum temperature above 44°C.
Looking at the temperatures during the February 1933 heatwave which occurred in a much cooler climate, it is clear that 6 consecutive 40°C Perth days are already a possibility in the current warmer climate, it is not a question of if but only when, highlighting the need for both climate change mitigation and adaptation. Heatwave frequency, duration and intensity are all increasing with climate change.
Maximum temperatures at the official Perth station during the February 1933 heatwave were:
February 3rd 1933: 39.8°C
February 4th 1933: 36.7°C
February 5th 1933: 38.8°C
February 6th 1933: 39.9°C
February 7th 1933: 44.3°C
February 8th 1933: 44.6°C
February 9th 1933: 42.3°C
February 10th 1933: 40.1°C
Tuesday January 11:
City:
18-37 Degrees Celsius
Hot and mostly sunny.
Chance of any rain:0%
Amount:Nil
Perth Metropolitan Area:
Mostly sunny.Very hot inland.Winds easterly at 20-30 km/h tending south-southwesterly in the afternoon and evening becoming south-southeasterly at 10-20 km/h later at night.
Wednesday January 12:
City:
23-38 Degrees Celsius
Very hot and sunny.
Chance of any rain:0%
Amount:Nil
Perth Metropolitan Area:
Very hot and sunny.Winds easterly at 15-25 km/h shifting southwesterly at 20-30 km/h by afternoon easing to 10-20 km/h at night.
Thursday January 13:
City:
19-28 Degrees Celsius
Clouds clearing.
Chance of any rain:5%
Amount:Nil
Perth Metropolitan Area:
Clouds clearing.Winds southwesterly at 15-25 km/h increasing to 20-30 km/h in the morning becoming south-southwesterly at night.
Friday January 14:
City:
17-29 Degrees Celsius
Mostly sunny.
Chance of any rain:0%
Amount:Nil
Perth Metropolitan Area:
Mostly sunny.Winds south-southeasterly at 10-20 km/h becoming south-southwesterly at 20-30 km/h by afternoon.
Saturday January 15:
City:
17-29 Degrees Celsius
Mostly sunny.
Chance of any rain:0%
Amount:Nil
Perth Metropolitan Area:
Mostly sunny.Winds south-southeasterly at 15-25 km/h tending south-southwesterly at 20-35 km/h in the afternoon and evening.
Sunday January 16:
City:
17-33 Degrees Celsius
Sunny.
Chance of any rain:0%
Amount:Nil
Perth Metropolitan Area:
Sunny.Winds southeasterly at 10-20 km/h tending south-southwesterly at 20-30 km/h in the afternoon and evening becoming east-southeasterly at 20-30 km/h later at night.
Monday January 17:
City: