A blistering heat wave is expected to begin Wednesday in Ontario, blanketing a zone from Windsor to as far north as Temagami in what feels like 40 C temperatures.

Thermometers in Toronto will hit a high of 35 C, Environment Canada predicts, but it’ll feel closer to 42 C with very sunny skies throughout the day.

Environment Canada describes the weather as “the longest and most significant heat wave of the summer so far.” Toronto’s Pearson International Airport weather station has already logged its driest summer on record.

“So people are saying: Is this a drought? Yes. There’s never been a drier period at Pearson in 75 years,” said Environment Canada climatologist Dave Phillips. Normally, he said, Toronto averages about 242 mm of rain a year. So far, only 44 per cent of this — 107 mm — has fallen.

While Tuesday’s daytime high held at around 30 C, GO Transit crews reported a “sun kink” on a Lakeshore East GO Train track near Pickering in the evening. Rails can warp or “kink” if exposed to high heat for prolonged periods of time, GO Transit said on its website.

Spokesperson Anne-Marie Aikins said GO trains will be running at slower than normal speeds until Friday, a precaution GO Transit uses to reduce the risk of more track damage during hot weather.

Natural Resources Canada was reporting Tuesday that the Greater Toronto Area was under extreme risk for wildland fires — such as scrub or grass. These kinds of fires could shut down whole GO lines if they’re too close to a rail corridor, Aikins added.

Days of above 30 C heat have become routine this summer. Thus far, Toronto has seen 27.

“This time last year, we had six of those suckers,” Phillips said.

Night won’t bring much relief. The coolest Toronto is expected to feel over the heat wave is 21 C on Friday night. Hot nights have been a staple of this summer, but Phillips said even this week’s stretch is expected to be warmer than before.

Thursday won’t be quite as blistering: the high is expected to be 32 C, with a mix of sun and cloud throughout the day. Clouds will begin rolling in later in the evening, bringing with them a 40 per cent chance of showers Friday. Even so, it’ll get as hot as 31 C.

That 40 per cent chance of showers is expected to carry over into the weekend, Environment Canada predicts. It’ll blunt the heat and humidity somewhat — Saturday is expected to only be 30 C, and Sunday could see a daytime high of just 24 C.

The summer of 2016 has seen frequent heat alerts and little rain — and farmers in particular haven’t had it easy.

“Oh, they’re really suffering,” Phillips said, especially in the Niagara region. Aside from a lack of rain, he was told that birds have been pecking at large quantities of fruit just to get at any residual moisture.

Trees are also losing their leaves early and growing limp, he said.

“The trees are suffering — they don’t look like they’re suffering, but they really are,” Phillips said.

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While next week is still far off, Monday is currently expected to be no warmer than 25 C with a mix of sun and cloud.

The City of Toronto issued a heat warning Tuesday, and opened seven cooling centres — as well as 170 local libraries and community centres — for folks looking to cool off. The city said the warning would be in effect “until further notice.”