Weather and Gardening Discussion

[MichaelS]

And the overnight lows not really getting all that low is part of it as well I think.

 

[Mountain Man]

We get these in the summer too though. Maybe it's just me, but 30 isn't worthy of a heat warning.

 

[CBBarnett]

We get these in the summer too though. Maybe it's just me, but 30 isn't worthy of a heat warning.

It's a bit of how you look at it. I have shared this before, but think it's a good one. Number of days per year with highs above 30:

The top 3 years were all in the past 5 years:

• 2021 = 21 days
• 2022 = 17 days
• 2024 = 16 days

Of those years, none had a 30 degree day in May. I think we have to go back to 2006 to have a 30 degree day this early.

So is it the biggest heat wave ever - no. And to your point, it's increasing more of the same in recent years. But that's probably why it's still a warning - this isn't "normal" still.

 

[ByeByeBaby]

Anyone know why we get a heat warning every time the temp comes close to 30? We never used to have them and now it happens every time.

I believe they take into account how close the temperature is to the recent average. So a 30-degree day after it's been 27 for two months may not get a warning, whereas the first 30-degree day after its been 10 degrees for two weeks might. I think that's why there has been a few lately.

Also might have something to do with the seasonal expectations: 30+ degrees in late May is not unheard of, but is 10+ degrees above normal averages.

It's pretty simple (I think this is even part of the heat warning message on my phone in the Environment Canada app):
When 2 or more consecutive days of daytime maximum temperatures are expected to reach 29°C or warmer and nighttime minimum temperatures are expected to fall to 14°C or warmer. (source)
That is, two hot days where it won't cool down enough at night to let things naturally cool off. Nothing to do with recent temperatures or when in the year it is. I wonder if we have higher humidity these days and that's keeping more warmth in the air in the evenings?

But there's a little nod to local climate: The above is the definition for Calgary (and as it happens it has been the same here for over a decade); in fact, it's the definition for Edmonton and Yellowknife as well. But in southern Alberta (ie Lethbridge, Medicine Hat, Pincher Creek) the max needs to be 32°C and the min is 16°C. In southern interior BC, it's 35°C and 18°C. On Baffin Island, a heat warning means a daytime high over 22°C.

 

[UrbanWarrior]

This heat is crazy, especially for May. Two days above 31⁰ in May, in Calgary. It's 6 pm right now and its 31⁰ with 13% humidity.

 

[Rollerstud98]

Very much looking forward to tomorrow.