New research supported by CPO’s Climate Variability and Predictability (CVP) Program sheds light on the large-scale climate processes that affect U.S. rainfall variability from August to October, which could help improve prediction. Led by NOAA AOML scientists and co-authored by NOAA’s National Weather Service, the study first shows that a well-established relationship between the Bermuda High, a high pressure area that sits over the Atlantic near Bermuda in the summer, and U.S. rainfall from June-August, does not apply to August-October rainfall. The authors instead link changes in August-October U.S. precipitation to a difference between abnormal sea surface temperatures in the tropical Pacific and the Atlantic. The study finds that this sea surface temperature contrast affects atmospheric convection in the Caribbean sea which, in turn, influences the North American Low-Level Jet, an atmospheric current that brings warm and moist air to the United States from the Gulf of Mexico. This pattern then ultimately affects U.S. rainfall from August to October. These findings address an important gap in understanding that could help advance prediction capability for U.S. summer to fall precipitation. The study is accepted for publication in the journal Geophysical Research Letters.