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At a Glance Temperatures are forecast to be above average in the East and Pacific Northwest this summer.

Parts of the Plains may see temperatures somewhat below average.

El Niño, computer model forecast guidance and high levels of soil moisture played roles in the summer forecast. Summer temperatures will be hotter than average on both U.S. coasts and cooler in the central part of the country, according to an outlook released Thursday by The Weather Company, an IBM Business.

In weather forecasting and historical records, summer encompasses June through August.

<img class="styles__noscript__2rw2y" src="https://s.w-x.co/util/image/w/wsi_june-august-0417.jpg?v=at&w=485&h=273" srcset="https://s.w-x.co/util/image/w/wsi_june-august-0417.jpg?v=at&w=485&h=273 400w, https://s.w-x.co/util/image/w/wsi_june-august-0417.jpg?v=ap&w=980&h=551 800w" > Summer Forecast (June-August)

El Niño, a factor used to determine the summer outlook, has a 65 percent chance of continuing through the summer months.

"El Niño summers suggest cooler risks across the northern/central Plains with warmth favored across the Pacific Northwest," said Dr. Todd Crawford , chief meteorologist at The Weather Company.

In the the northern Plains and upper Midwest, soil moisture is much above average, and that can have a cooling effect on temperatures near the Earth's surface.

Long-term computer model forecast guidance indicates the East will be warmer than average.

Keep in mind that these outlooks are overall trends over a three-month period from June through August. An individual cold front or an upper ridge of high pressure can lead to a period of colder or warmer weather, respectively, that bucks the overall three-month trend.

Here's a breakdown of how the forecast evolves each month from June through August.

June

The Pacific Northwest, Southeast and mid-Atlantic are favored to see above-average warmth as summer kicks off in June.

Cooler-than-average temperatures are most likely in the northern Plains and upper Midwest.

<img class="styles__noscript__2rw2y" src="https://s.w-x.co/util/image/w/wsi_june_0417.jpg?v=at&w=485&h=273" srcset="https://s.w-x.co/util/image/w/wsi_june_0417.jpg?v=at&w=485&h=273 400w, https://s.w-x.co/util/image/w/wsi_june_0417.jpg?v=ap&w=980&h=551 800w" > June Outlook

Jul y

The area favored to see below-average temperatures grows in July across the northern and central Plains and upper Midwest.

In addition, the hotter-than-average conditions in the East are expected to shift toward the Northeast. The Pacific Northwest warmth is expected to expand farther southward to include parts of Nevada and California.

<img class="styles__noscript__2rw2y" src="https://s.w-x.co/util/image/w/wsi_july_0417.jpg?v=at&w=485&h=273" srcset="https://s.w-x.co/util/image/w/wsi_july_0417.jpg?v=at&w=485&h=273 400w, https://s.w-x.co/util/image/w/wsi_july_0417.jpg?v=ap&w=980&h=551 800w" > July Outlook

August

Summer's final month could bring heat and humidity to much of the East Coast. A continuation of warmer-than-average temperatures is forecast from the Northwest into Northern California.

Meanwhile, the relatively cool summer trend may continue in the Plains and Midwest.