Scientists have developed a way to predict severe heat waves months before they happen

In a study published this week in Nature Geoscience journal, researchers from National Center for Atmospheric Research explain how ocean surface temperatures may correlate with a heat wave. Researchers began by examining climate data from the Eastern United States between the years of 1982 and 2015. They then identified sweltering summer days, defined as being 12 degrees hotter than average summer temperatures, and compared this data with ocean surface temperatures in the North Pacific during these same warm periods.

It quickly became apparent that a rise in ocean surface temperature was associated with a future heat wave. “The pattern popped out at us really clearly,” said postdoctoral researcher and lead author Karen A. McKinnon of the National Center for Atmospheric Research. Not only was this pattern very easy to spot, but it also was observed “up to seven weeks before” the heat wave materialized on the East coast. Researchers are not sure how a rise in Pacific ocean surface temperature can influence weather on the East Coast, but some climate scientists believe it has to do with the interaction between the ocean water and the jet stream.

With current models, heat waves can only be predicted reliably on a short-term basis, providing just a few days of notice before they occur. Existing long-term weather probability tools do not help for heat waves, as they provide only overall weather trends and do not include temperature extremes. The ability to predict heat waves this far in advance would be extremely useful for farmers, city officials and emergency planners who must deal with heat-associated crop losses, increased energy requirements and heat-related illness.