Historical trends

Each point is one year's summary statistic, calculated the same way as on the daily page: every day's high or low compared with NOAA's 1991–2020 normal for that date. Click a point to see that year day by day.

Data: NOAA daily observations and 1991–2020 daily normals from the ACIS web service (data.rcc-acis.org), for the city's official climate station. Years with fewer than 300 days of complete readings are left out; in years with a few missing days, the day counts can be slightly low. Trend lines are ordinary least-squares fits over the complete years shown. “All cities” pools every city with a complete record that year (each city against its own normals), starting in 1948, the first year at least three quarters of the cities have records; its day counts are shown as percentages of city-days. Because every year is compared with the same 1991–2020 normals, years before 1991 tend to sit below zero and recent years above it when a station has warmed.