Southern and central Manitoba are in the grips of the second heat wave in as many weeks, with temperatures in the high 30s and humidex advisories across the regions.

Temperatures were forecast to reach as high as 38 C in Manitoba Monday, with humidex values in the mid-40s.

"People should stay inside and stay well-hydrated," said Environment Canada's Cara Patton. "If they have to go outside, make sure that you're in a shady area and you take lots of breaks. And remember the sunscreen. And also remember about your pets, because they feel the humidity, too."

Dave Phillips, senior climatologist at Environment Canada, blamed the "jungle-like" conditions on hot, humid air from the Gulf of Mexico combining with the moisture from heavy rain that fell earlier this year.

"May, June, even July, you've had about 22 per cent more rain. That is now evaporating into the air, which makes it a little steamier," he said.

"Also the crops, those flourishing crops both in the Midwest part of the United States and in the eastern Prairies, is just transpiring probably at their peak right now, and that's adding more ... moisture into the air."

More surgeries cancelled at city hospitals

The Grace and Concordia hospitals in Winnipeg have cancelled 25 surgeries because the high humidity is making it difficult to keep equipment sterile.

Brock Wright with the Winnipeg Regional Health Authority says, "There is the potential that if these cases are prioritized ... of higher priority than some of the scheduled cases, it could impact other patients," he said. "We will obviously try to minimize that. We are looking at opportunities to increase surgical elective time during this period so that we can make up the backlog."

Short-term fixes, such as portable dehumidifiers, are being put in place while engineers and maintenance staff work on modifying the systems in the long term to avoid the problem, Wright said.

Wright could not recall another time in Winnipeg when surgeries were delayed by a similar problem - although hospitals in Saskatchewan have been struggling with the same issue.

10-degree drop expected midweek

Hot and humid conditions often brew storms in Manitoba, but only scattered storms have been reported so far.

"I think perhaps what's surprised maybe a lot of meteorologists, forecasters, is with all this heat and humidity on the Prairies, severe weather hasn't broken out everywhere," Phillips said. "You've had occasions of that, but not to the extent you might expect."

Southern Manitobans endured extremely high temperatures throughout most of last week.

Several communities broke their daily temperature records and the town of Carman, southwest of Winnipeg, set a new Canadian humidex record of 53 C on Wednesday. Wilted Manitobans can expect to see some relief - at least in the short term - later this week.

A cooler air mass forecast to move into the area Tuesday night should cool the area about 10 degrees, to average seasonal levels, on Wednesday and Thursday, Environment Canada predicts.

But the mercury is expected to climb back into the 30s for the August long weekend.