For summer vs winter, event and type. Events are chosen that have a consistent signal throughout the entire season. Years that define the events are listed on the main page. Season Winter is defined from November to March. Summer for May through September.
Years given are the year of the last month of the season.
Type Means and Anomalies. Sea Level Pressure Climate Division Temperature Surface temperature averaged over US state climate divisions. Climate Division Precipitation Precipitation averaged over US state climate divisions. Positive values indicate winds from the west. Positive values indicate winds from the south.