Unprecedented heat has broken hundreds of records across the western United States so far this September, with Sacramento, California, hitting a new all-time high of 116 degrees Fahrenheit on Tuesday and a September record of 125 F being tied in Death Valley. As the stifling warmth begins to ease across parts of the West, the Northwest will heat up.

AccuWeather meteorologists say a "heat dome" that has been parked over the Southwest and Great Basin for over a week finally began to break down by Friday on. Underneath a heat dome, the air sinks, causing temperatures to climb and precipitation and cloud cover to generally be limited.

Part of this change in the pattern will be attributed to Tropical Storm Kay, which was tracking northward toward Southern California on Thursday. While the brunt of the storm will stay offshore, the clouds and the rain will help send temperatures to lower levels.

Meanwhile, a dip in the jet stream will occur over the northern Rockies and eventually the northern Plains. As a result, places such as Salt Lake City, which was at or above 100 degrees Fahrenheit through the first seven days of September, was only in the mid-80s on Saturday. However, that is a normal high in Utah's capital city for early September.

To the north of Kay and west of the jet stream dip, heat will be allowed to push northward into the Pacific Northwest. This will shift record-challenging heat into Washington, Oregon and Idaho. While monthly records and all-time records are not expected to be broken as they were elsewhere in the West over the past week, some daily records will be in jeopardy.

Seattle passed the 90 degree mark on Saturday, reaching a high of 91, tying the daily record high set just two years ago.

The normal high temperature in Seattle never gets above 79 degrees at any point during the year, so this will be warm by any standard.

The Seattle area has recorded temperatures about 1-2 degrees above normal this month, but farther south, locations in southeastern Oregon have been as much as 15 degrees above normal through the first seven days of September.

The hotter weather will again be found farther south along the Interstate 5 corridor this weekend.

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AccuWeather is currently forecasting temperatures in Portland, Oregon and Seattle to peak 15 degrees above the normal high in mid-September, and as much as 10 degrees above the average highest temperature mid-summer.

With the heat arriving from the south, near-record warmth will begin a day earlier in southern Oregon.

Medford, Oregon, located near the California border, is expected to threaten a record on Saturday as well, with the forecast high of 105 breaking the record of 104 degrees set exactly 100 years ago.

Besides the heat, other factors could increase the risk of dangerous wildfires. Red flag warnings, which indicate a high fire danger, have been issued for parts of western Oregon and western Washington.

"Dry vegetation and winds that could gust up to 30 mph at times will cause a very high fire threat with any fires potentially getting out of control quickly," cautioned Geiger.

Cooler weather is expected by early next week, with temperatures possibly even dropping below normal by Tuesday. Despite the lower temperatures, any precipitation is likely to be confined to areas well inland from the coast, according to AccuWeather meteorologists.