Not just a 'dry heat': why humidity is surging in Sask. this summer

Saskatchewan is known for its hot and dry summers.

But this summer, things haven't been so dry.

Humidex values during the last full week of July soared above 40 in parts of southern Saskatchewan.

Estevan reported 12 days this July with a humidex at or above 35. It usually sees about four or five days in a typical July.

Humidex — a word that blends "humidity" and "index" — measures how hot it feels when humidity is combined with temperature. The higher the humidity on a hot day, the hotter it actually feels.

A humidex of 40 to 45, according to Environment and Climate Change Canada (ECCC), can cause "great discomfort" and it's recommended you avoid physical exertion.

Humidex is also a factor ECCC considers when issuing heat warnings. In roughly the southern half of the province, they're issued when the humidex exceeds 38 for two or more consecutive days; and in roughly the northern half, they're issued when it exceeds 34.

Humidity is the amount of water vapour — or water in the form of a gas instead of a liquid — in the air.

That water vapour is formed when water evaporates from the ground into the air.

And there's been plenty of water on the ground for that to happen, with much of the province receiving above-average moisture this spring and summer.

On the Prairies, some amount of humidity is almost always guaranteed each summer when crops grow.

"They give off a tremendous amount of moisture called evapotranspiration," said Terry Lang, a meteorologist with ECCC.

"The past few years have been really, really dry and we know the crops haven't done really well so they haven't been giving off this evapotranspiration."

Lang said strong weather systems that originate off the coast of British Columbia and move through the Prairies in summer not only bring additional rain, but they also can draw in moist air from the Gulf of Mexico.