The colors show the frequency of cold or warm winters during the 11 strong El Niños that occurred from 1940-2023. Places where more than half (6 or more) the El Niño winters were warmer than average by any amount are colored red. (Whether a winter was above- or below-average was based on comparison with a 30-year rolling average centered on the winter in question.) Places where more than half the El Niño winters were cooler than average by any amount are colored blue. Most of the Great Lakes region is colored red, meaning that warmer-than-average winters were more common than cooler-than-average winters. NOAA Climate.gov map, based on analysis of ERA5 data by Brian Brettschneider.