Excessive heat watches and red flag warnings were in effect across the northwestern United States Wednesday as record heat began building in some places and AccuWeather forecasters along with local officials are warning that the weather is going to become a lot hotter in the coming days.

“We’re going to be looking at all-time record highs in some spots,” AccuWeather Chief Broadcast Meteorologist Bernie Rayno warned for a part of the country where air conditioning is not a staple in homes. Rayno said some of the places that will see temps soar farthest above normal include those along the Interstate-5 corridor between Seattle and Portland.

Indeed, Seattle Mayor Jenny Durkin this week issued guidance outlining ways for residents to stay cool during the unusual warm spell. And the National Weather Service (NWS) office in Seattle provided tips for keeping homes that don’t have air conditioning cool during a heat wave.

It is not just the northwestern U.S. where all-time record highs may be set. There is the potential for a new Canada high temperature mark to be set with the heat wave this weekend to early next week. That temperature is 113 F or 45 C and was set on July 5, 1937, at Midale and Yellow Grass, Saskatchewan.

“Kamloops, Kelowna and Lillooet, British Columbia, all have a shot at reaching or slightly exceeding the all-time Canada high temperature mark,” AccuWeather Senior Meteorologist Brett Anderson said.

Part of the Northwest got a little taste of the extreme heat on Monday, which was the first full day of summer. Several daily high-temperature records were set or challenged in western Washington and Oregon.

The temperature in Portland, Oregon, soared to 97 Monday and broke the old record of 96 set in 1992. Meanwhile, in Vancouver, Washington, the temperature shattered the old record of 91 set in 1938 with a high of 95.

Seattle just missed its first 90-degree reading of the season Monday, but then the heat backed off and the temperature didn’t even reach 80 on Tuesday. However, people in the city will likely not have much longer to wait to hit the 90-degree mark this summer.

As a weak storm system pushes slowly inland from the Pacific Ocean into Thursday, temperatures will be held back temporarily in coastal areas of the Northwest.

The slight cooldown will trim temperatures back to 5-10 degrees above average into Thursday, before a shift in the jet stream is expected to turn the atmospheric furnace on high Friday, Saturday and Sunday.

Average highs this time of year range from near 70 in northwestern Washington to the mid-70s along the Oregon coast and eastern Washington to near 80 along in far eastern Oregon along the Idaho border. Seattle’s high temperatures will be in the upper 70s to near 80 Wednesday and Thursday, while temperatures in Portland will reach in the mid-80s into Thursday. It will be a tad warmer, with highs registering in the upper 80s in Spokane the next few days.