Hoar frost spotted in southwestern Ontario: What is it, exactly?
Sub-freezing temperatures resulted in the formation of hoar frost in Guelph, Ontario Tuesday morning.
Weather Network meteorologist and stormhunter Mark Robinson captured the phenomenon on camera.
"Look at that!" he said, examining a crystallized goldenrod.
"[This is] very unusual for southern Ontario, but you can see it once in awhile."
Hoar frost in Guelph, Ont. on February 11, 2025. (Mark Robinson, The Weather Network)
Robinson, standing in a field, then pointed to some tall trees, noting frost formations at the tops, but none on the lower parts.
"That's kind of neat, I wasn't expecting that," he said.
Robinson noted hoar frost "over everything," around him Tuesday morning, especially in places closer to the river.
Watch here:
Here's a look at hoar frost captured by the Pacific Northwest Seismic Network last week:
Happy #FieldworkFriday! This winter season keeps providing, with some incredible hoar frost by site ODUC. It grows in low temp & high moisture areas, where sunlight & precipitation haven't yet reached. Sol Duc Valley had perfect conditions for growing these crystals as of late! pic.twitter.com/qaWdR8Jp6Z
— PNSN (@PNSN1) February 7, 2025
Hoar frost and rime ice are two winter phenomenon that resemble one another, and form ins somewhat similar, albeit very specific, conditions.
“Rime ice forms on cold days and nights when the atmosphere is calm,” explains Kelly Sonnenburg, a meteorologist at The Weather Network.
“Water droplets freeze on surfaces, creating needle-like structures that can sometimes grow in strange ways, depending on the wind direction.”
Rime ice captured in Fort Frances, Ont., on Dec. 29, 2023 (Anika Beaudry, The Weather Network)
Rime ice in Calgary, Alberta on Nov. 28, 2024. (Connor O'Donovan/The Weather Network)
"Hoar frost forms in a somewhat similar way but doesn’t require as much moisture. Water vapour molecules contact a sub-freezing surface and bypass the liquid stage, forming fluffy, light, solid ice crystals on the surface."
(Graphic displays how hoar frost develops)
While the accumulation of ice and snow can be beautiful, it can also lead to some damage as it weighs down branches and powerlines.
For example, multiple days of fog and freezing fog on the central Prairies in early December 2018 resulted in more than 30,000 calls from Saskatchewan residents, reporting power outages.
