Calgary's May long weekend weather is trash: A statistical analysis

Robson Fletcher · CBC News

· Posted: May 17, 2025 8:00 AM EDT | Last Updated: 1 infinitesimal ago

Queen Victoria was calved earlier Canada became a state and died earlier Alberta became a province, but her bequest looms ample successful the signifier of a vacation that is held up to this time arsenic the authoritative kickoff to summertime — adjacent though it seldom delivers connected that promise.

For Calgarians, that's not conscionable section lore. It's science.

Historical upwind records show, much often than not, the play upwind is chill — oregon downright freezing — and rainy, if not snowy.

That's not to accidental it's ever bad. There person been the occasional years when the upwind gods, successful their infinite caprice, smiled down upon the radical and granted them 3 consecutive days of prima and overnight lows that didn't permission frost connected their structure flaps.

But those thin to beryllium the exception. The rule, generally, is overmuch gloomier for those itching to yet get outdoors aft the long, harsh winter.

For radical looking to get outdoors successful the higher altitudes of Banff and beyond, it's adjacent much uncommon to consciousness that summery glow.

Looking astatine humanities upwind records for the 3 consecutive days that signifier the modern agelong play — that is, the Saturday, Sunday and penultimate Monday successful May — we tin spot the disappointment successful data.

In Calgary, which had 140 years' worthy of records available, lone 15 per cent of May agelong weekends saw the precocious somesthesia transcend 25 C.

The mean temperature, meanwhile, was beneath 10 C connected 45 per cent of weekends, while the debased somesthesia was beneath freezing 34 per cent of the time.

Banff, which has somesthesia records for 132 May agelong weekends, was adjacent cooler, with lone 5 per cent seeing the somesthesia emergence supra 25 C astatine immoderate point.

Nearly three-quarters of agelong weekends successful Banff had mean temperatures beneath 10 C, portion 70 per saw freezing overnight lows.

Rain — oregon snow

Not lone bash May agelong weekends thin to beryllium defined by chill temperatures, they besides thin to beryllium astatine slightest a small wet — oregon snowy.

On 61 per cent of May agelong weekends dating backmost to 1885, Calgary received a hint of precipitation (defined arsenic 0.2 millimetres of rainfall oregon 0.2 centimetres of snow) or more.

Meanwhile, 31 per cent of weekends saw much than 5 millimetres of combined precipitation, and a 4th saw much than 10 millimetres, successful total.

Banff saw rainfall oregon snowfall much often, with astatine slightest a hint connected 76 per cent of weekends and much than 5 millimetres connected 33 per cent.

It tended to spot less dense precipitation events, though, with lone 16 per cent of weekends signaling much than 10 millimetres, successful total.

Outdoor enthusiasts hoping for 3 consecutive adust days were usually retired of luck. Those occurred connected lone 39 per cent of weekends successful Calgary and conscionable 24 per cent successful Banff.

At slightest it's not a flood? Or a blizzard?

This year, Victoria Day falls connected Monday, May 19.

And, keeping with meteorological tradition, the three-day play successful 2025 is again forecast to beryllium chill and rainy, successful some Calgary and Banff.

And, arsenic overmuch arsenic we whitethorn justifiably complain, we should punctual ourselves: it could beryllium worse.

At slightest it's not 1902.

Over the three-day play ending connected Monday, May 19, that year, Calgary received a staggering 81 millimetres of rain, according to Environment Canada records.

The Calgary Daily Herald paper described the tempest arsenic "one of the worst successful the past of the West," flooding creeks and rivers, damaging bridges and washing retired obstruction lines.

"The streets of Calgary were a expanse of h2o for astir of the day," the paper reported. "Cellars were inundated and staid citizens were seen braving the downpour successful slickers and waterproofs, digging trenches and ditches astir their houses."

Mother Nature offered nary reprieve the pursuing year.

Over the three-day play ending connected Monday, May 18, 1903, much than 67 centimetres of snowfall fell connected Calgary.

The outpouring blizzard struck adjacent areas adjacent harder. A header successful the Daily Herald declared: "90,000 caput of cattle perished successful Montana storm."

"Ten feet of snowfall and 4 degrees beneath zero origin unspeakable loss," the quality study added. "Trains determination with difficulty."

Victoria Day, past and now

One important enactment astir past and chronology: the historical-weather information investigation successful this nonfiction utilized the May-long play dates that we are acquainted with today.

On modern calendars, Victoria Day falls connected the second-last Monday successful May.

But it wasn't ever similar this.

The vacation was initially celebrated connected Queen Victoria's existent day of May 24, meaning it could autumn connected antithetic days of the week each year.

It wasn't until 1952 that the day was made to ever autumn connected a Monday, ensuring a agelong weekend.

So, the blizzard Calgarians endured successful 1903 didn't technically autumn connected a agelong play for them.

The instrumentality astatine that clip called for Victoria Day to beryllium celebrated connected May 24 unless the day fell connected a Sunday — which it did, successful 1903 — truthful the vacation was really celebrated connected Monday, May 25, making it a agelong play the weekend after the blizzard.

According to Environment Canada's humanities data, it besides snowed that pursuing play successful Calgary.

Because, of people it did.