Vancouver broke an unexpected weather record this week
If the past week felt unusually muggy across Metro Vancouver, it wasn’t just your imagination
An unseasonable pattern draped across Western Canada this past week helped to shatter Canada’s all-time hottest September temperature on Wednesday.
Now, the same pattern helped break another unusual weather record—this time in Vancouver.
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It’s not just your imagination if you’ve noticed a curious level of stickiness to the air lately.
Friday, Sept. 5, will go down as Vancouver’s muggiest September day on record after the airport measured a dew point value of 19.9°C.
This astounding value breaks the previous dew point record of 19.8°C set just two days earlier. Before this year, you have to go back to 2017 to find a September day with a similar humid feel.
Dew point is the best measure of how comfortable or muggy the air feels on any given day. The dew point is the temperature at which the air becomes fully saturated with moisture, reaching 100 per cent relative humidity.
Dew point values below 15°C are generally considered comfortable. A dew point between 15°C and 18°C feels humid. It’s noticeably muggy when the dew point is between 18°C and 21°C, and a dew point any higher than 21°C feels downright tropical.
For context, Vancouver’s dew point value of 19.9°C on Sept. 5 was similar to readings down in Savannah, Georgia, and New Orleans, Louisiana, that same afternoon.
Vancouver is a long way from partying on the French Quarter—so why did we have Louisiana-like humidity?
The culprit behind this past week’s humidity is a blocking ridge of high pressure that cranked up the heat across much of B.C. Moist southerly flow moving into the region got trapped beneath this ridge, pooling up across the Lower Mainland to make the air feel sticky.
Exceptionally muggy days are rare around Metro Vancouver because of some ‘safety nets’ built into the environment across the region.
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A combination of westerly winds, low sea surface temperatures, and a lower sun angle all work together to keep dew point values lower.
Consider those factors as opposed to somewhere like the Gulf Coast, where hot temperatures, long days, and steamy sea surface temperatures can pump a seemingly endless supply of moisture into the atmosphere.
If you’re curious, the world’s highest-ever dew point was a value of 35°C in Dhahran, Saudi Arabia, in July 2003. Communities bordering the Persian Gulf often experience dangerous levels of heat and humidity, capable of causing heat exhaustion or heat stroke in a matter of minutes.