Temperatures in May in the northern and eastern United States will be warmer than average overall, according to an updated outlook released Sunday by The Weather Company, an IBM Business. The summer forecast remains unchanged from previous outlooks and continues to call for above-average temperatures in a large part of the Lower 48.

In May, areas from the Northwest through the Midwest and Great Lakes are forecast to see temperatures the farthest above average. The expectation for a warmer than average May in the Northwest comes on the heels of the warmest April on record in Seattle and Portland, Oregon.

"The best chance for significantly above-normal temperatures will continue to be in the Pacific Northwest into the northern Plains, while the southern Plains will likely continue relatively cool and wet," said Dr. Todd Crawford, chief meteorologist.

There remains a bit of uncertainty regarding parts of the eastern U.S. for May, but temperatures should be at least near average and probably a bit above average.

Keep in mind, these outlooks are overall trends for the entire month. An individual cold front or an upper ridge of high pressure can lead to a brief period of colder or warmer weather, respectively.

June-August

"The scales are currently tipped toward warmer than average summers," Crawford said. "In fact, the past six summers have been the hottest six-year stretch in the last 120 years and this summer should continue the recent trend."

Well-above-average temperatures are expected this summer for the northern tier of states from the Pacific Northwest into the northern Plains, Great Lakes and Northeast.

Warmer-than-average temperatures will also extend from California through the central and southern Plains and Southeast.

The only area where cooler than average temperatures are expected this summer will be across much of Texas to Louisiana.

"The historically strong El Nino event is weakening rapidly and we should transition to La Nina conditions by summer and this favors another hot summer, especially across the northern U.S.," said Dr. Crawford.

Another factor to consider regarding temperatures this summer are sea surface temperatures in the western North Atlantic, which are forecast to be warmer than we have seen over the past five years. That often results in warmer temperatures in the eastern U.S. In addition, conditions across the Pacific Ocean, influenced by the strong El Nino, will favor warmer-than-average temperatures across much of the West, especially the Pacific Northwest.

Most computer forecast models continue to suggest that the transition from El Nino to La Nina conditions will occur this summer. Typically, La Nina summers feature hotter temperatures from the central U.S. into the Northeast, with the hottest month being July.

Crawford notes that during previous years where rapid changes from El Nino to La Nina occurred, the worst of the summer heat was focused from the northern Plains to the Great Lakes states.

Overall, computer model guidance indicates widespread warmth with little hint of cooler than average temperatures across the nation. The West will likely see warm and dry conditions, strongly influenced by the recent El Nino.

The heat should be less significant across the southern states where temperatures should generally average around to slightly above average.

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