PORTLAND, Ore. (KOIN) -- September is known for comfortable temperatures, sunny skies, and the start of Oregon and Washington's fall foliage.

It's a toasty start to the ninth month of the year here in Portland, but a cooling trend is expected over the next four weeks. Despite the 90-degree heat expected early this week, Portland typically sees the 90-degree heat fade by the first week of the month. On average, the final 90-degree high seen during the summer season is September 6. However, it's gone as late as October 5 in 1980.

Portland typically loses almost 10-degrees of warmth, increases the rain accumulation to 1.52 inches and loses 89 minutes of daylight. All of this combines together to give Portland a new monthly average of high of 77-degrees.

The Climate Prediction Center is hin

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