Some of the hottest temperatures of the year will be seen today in the Red River Valley as extremely warm air is brought into the province by a low pressure system passing through the northern Interlake.

Southerly winds have brought some of the warmest air yet this year over southern Manitoba. 850mb temperatures have climbed to 25°C today which, when combined with southerly winds at the surface, will help to push our daytime highs towards the mid-30’s. There is fairly good agreement among the models that winds will remain southerly in the Red River Valley through the day; this will eliminate any significant downslope effects and make temperature forecasting a little bit easier.

In general, daytime highs should range from 34-36°C through the RRV tomorrow, with the warmer temperatures closer to the American border. There is a slight chance that a few areas in the SW RRV could see highs push a degree or two higher than that (35-37°C), but such temperatures would be fairly localized. Winnipeg will have a chance of breaking it’s record high for today, which was set in 1972 when the temperature climbed to 36.1°C. It’s by no means a guarantee that we’ll break it, but we’ll certainly take a good run at it.

Dewpoints will climb to around the 18°C mark, however some areas may see dewpoints peak at 21-22°C before we start mixing air near the surface a little deeper into the atmosphere. This will result in humidex values between 39-45. It’s quite likely we’ll see a humidex advisory issued by the Winnipeg SPC later today.

Manitoba Health suggests Manitoba residents take precautions against heat-related illnesses whenever the humidex climbs above 37. Manitoba Health advises the following:

• Stay aware and be prepared
  • Know daytime and night-time temperatures-both outdoors and indoors- by checking your local weather forecasts and the thermostat in your home.
  • Stay up to date on weather alerts so you know when to take extra-care.
  • If you have an air-conditioner, make sure it’s working properly before the hot weather starts.
• Stay hydrated
  • Drink plenty of water (that’s the best liquid) before you feel thirsty.
  • Avoid alcoholic beverages, as they can increase the amount of water lost by the body.
• Stay cool and keep out of the sun
  • Plan outdoor activities for cooler parts of the day, but remember to wear insect repellant since mosquitoes are out too.
  • If you are outdoors during the hottest part of the day, shade yourself from the sun with an umbrella or a wide-brimmed hat with lots of ventilation (to allow the sweat on your head to evaporate), wear loose-fitting, breathable, light-coloured clothing, and remember to wear sunscreen to limit ultra-violet (UV) ray exposure.
  • If there is no air-conditioning at home- go to a cool place such as an air-conditioned mall, public library, or community centre.
  • Take a cool bath or shower or go for a swim to cool off.
  • Avoid using your oven or other appliances that could heat your home more.
  • Limit physical activities during the hotter parts of the day or exercise in an air-conditioned place.
• Take care of yourself and others
  • Check on family members, neighbours and friends – especially older adults and those with chronic conditions. Visiting is best because it is easier to identify signs of heat illness that could be missed over the phone.
  • Never leave people or pets in your care alone in closed vehicles or direct sunlight.

— Heat and Your Health; Manitoba Health

A cold front will sweep through this evening, bringing more seasonal air back to the province. There is very little chance of any precipitation with the passage of this front.

The rest of the week will bring closer-to-seasonal temperatures with daytime highs near 28°C. The normal daytime high for Winnipeg for this time of year is about 22°C. The normal overnight low is around 9°C. Our blast of hot weather will likely ensure that Winnipeg has it’s 14th consecutive month with above-normal temperatures. We’ll have our regular post on Friday, and then two posts on Saturday: the regularly scheduled Elsewhere in Weather News and a climate summary of August/update on 2012.