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Hot, sticky weather settles in over Ontario, Quebec, Eastern Canada

Hot, sticky weather settles in over Ontario, Quebec, Eastern Canada

If you're living anywhere from the Great Lakes out to Atlantic Canada, be ready for a sweaty, uncomfortable week, as a hot, humid weather system has settled in over the eastern half of the country, and it doesn't look like it's going anywhere anytime soon.

Temperatures are expected to top 30 degrees from Windsor all the way to Sydney, Nova Scotia, and even north of Lake Huron today as hot, humid weather pushes up from the United States. Although Atlantic Canada is expected to get some relief by as early as tomorrow, southern Ontario and southern Quebec will be in it for the long-haul as the heat sticks around for most of the week, and, as is typical in these situations, it's not the heat, but the humidity that's going to get you.

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Environment Canada has issued humidex advisories that extend from the eastern and northern shores of Lake Huron through the rest of southern Ontario, and over in New Brunwick as well. Quebec isn't being spared this, though. Southwestern Quebec, around Metro Montreal, up the St. Lawrence Valley to Quebec City and up the Ottawa River Valley are actually under a heat and humidity warning, since their humidex values are expected to get up above 40 today.

Humidex is that 'feels like' value that shows up in weather forecasts; kind of the opposite of the 'wind chill'. Rather than us having to deal with temperature and humidity separately, and know how they affect each other and so forth, we're just given one number that rolls it all together. If the temperature is 22 and the 'feels like' humidex value is 30, then if you go outside, won't feel like it's a nice mild 22 degrees, it'll feel more like it's a hot 30 degrees. When the humidex values get above 30, that's when it start to get uncomfortable, and you could end up suffering from heat exhaustion or even heat stroke if you're outside too long. Go above 45 and it's dangerous, and heat exhaustion and heat stroke hit you even quicker.

The humidity has such a strong effect on us because of how our bodies work. Whatever your normal temperature is (for most it's 37 degrees C), your body tries to maintain that, no matter what. When you get hot, you sweat, but but that's not the only thing that's needed in order to cool you down. You need that sweat to evaporate. Turning that liquid water into water vapour uses up energy, which is taken directly from your skin. That cools down your skin and the blood flowing through the tiny blood vessels that run through the skin, and that cooling of your blood helps maintain your body temperature.

When your sweat turns into water vapour, that water vapour gets absorbed by the air, and this is where we run into trouble when it comes to this kind of weather.

When it's really humid out, the air can't absorb water as well as it can when it's drier. In fact, the more humid it is, the harder it gets. Your body doesn't know the difference, so it's going to keep on putting out sweat, hoping that it will evaporate and the air will absorb the resulting water vapour. You can wipe away the sweat no problem, and that makes you feel better temporarily, but since it's the evaporation of the sweat that pulls the extra heat out of your body, wiping away the sweat doesn't do you as much good for cooling down your body temperature.

Drinking more fluids in these conditions will keep your body from dehydrating as it continues to sweat, and if it's cool water, it will absorb some of the excess heat in your body as it warms up to your body temperature, which will also help you cool down some. Staying out of the direct sunlight as much as possible helps too, because your body won't heat up as quickly. Some of the best things, though, are to just take it easy on the outdoor physical activity for this week, and if you do need to be outside, take breaks to get out of the heat and humidity for awhile, to give your body a chance to do its thing.

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It's looking like Ontario will be this weather for the week, as the temperatures are expected to remain at or above 30°C until Friday and the humidity will be sticking around as well. Quebec has it a bit more concentrated, but it looks like they'll be into slightly 'better' weather (read: cloudy and rainy) starting on Thursday.

As it also typical with this kind of weather, watch out for worsening air quality as the week progresses, and expect late-day thunderstorms to break out too, especially into Thursday and Friday.

(Photo courtesy: The Canadian Press)

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