Summer arrives in Pacific Northwest with first heat wave of season

Summer will finally make an appearance in the Pacific Northwest this weekend after an unusually cool and wet spring, but it's not all good news as temperatures are expected to reach dangerously hot levels.

Heat Advisories have been issued by the National Weather Service from western Washington into western Oregon and parts of Northern California for Saturday, Sunday and Monday. Seattle and Portland, Oregon, are both included in these advisories.

Highs are forecast to climb into the 90s across much of the region, with 100s farther south into the Central Valley of California. These temperatures are 10 to 25 degrees above average for this time of year.

Portland is forecast to reach the lower 90s on Saturday, while Medford, Oregon, could soar into the lower 100s.

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On Sunday, Portland could make a run at 100 degrees, while Medford might approach 105.

Seattle will be cooler and likely hold in the mid-80s, but this is still unseasonably hot for Emerald City. Its average high in late June is only in the lower 70s.

While most places in Oregon and Northern California won't be quite as hot on Monday, that's not the case in Washington state.

The first 90-degree day of the year appears likely for Seattle on Monday, which only averages three such days per year.

Farther east, cities in the Snake River Valley of Idaho, including Boise, could reach 100 degrees or higher on Monday.

Despite the heat in the Pacific Northwest, rivers across the region are still running cold and fast and will continue to do so this weekend.

The NWS office in Portland noticed that nearly every year, people die after attempting to swim in rivers in southwestern Washington and northwestern Oregon due to the cold water shock during the season's first heat wave.

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