For the next three months, above-normal temperatures are favored across the United States, from coast to coast and Mexico to Canada, as well as Alaska, according to government forecasts.
In archives that go back to 1995, that's never happened, Dan Collins, a forecaster with the National Oceanic and Atmospheric Administration's Climate Prediction Center, said.
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While it doesn't mean that a three-month-long heat wave is in store, or that there won't be cooler spells here and there, it does up the odds that 2016 will rank among the hottest years on record for the country. It's also a mark of the overall warming trend, courtesy of heat-trapping greenhouse gases accumulating in the atmosphere.
Warm Oceans, Rising Temperatures
The CPC puts out forecasts for temperatures and precipitation across the country that look across an entire month or season. Unlike weather forecasts, which deal with actual temperatures and storms, these climate outlooks look at the relative probabilities that temperatures or precipitation will be above-normal, below-normal, or normal.
The most recent three-month outlook, covering August, September and October, favors above-normal temperatures for every part of the Lower 48, as well as for all of Alaska.
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Driving that outlook are the warm sea surface temperatures across the globe, including in the Pacific, along the coast of Alaska, and in the Atlantic. The ocean has a longer memory for temperature than the land or air, so it tends to retain warmth for longer and influence atmospheric temperatures.
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