Summary Introduction Letter
The Climate Challenge*
Nearly every environmental indicator in the 2024 annual report has a tie to the climate. The trend over more than sixty years suggests that Connecticut’s climate is getting warmer, and precipitation is increasing.
The state’s warming climate is evidenced by increasing annual average temperature, precipitation, annual cooling degree days (CDD) and growing degree days (GDD), and decreasing annual heating degree days (HDD).1
The trend for annual HDD is decreasing while the trends for annual CDD and GDD are increasing from 1961 to present. HDD for 2024 (4,852) was 19 percent less than the annual average since 1961, while CDD (1,183) and GDD (3,831) for 2024 were 44 and 25 percent greater, respectively, than the annual average since 1961.
Annual precipitation for 2024 (45”) was 2.5 percent less than the annual average since 1960 (46.1”). The number of days in 2024 with rainfall greater than one inch (11) was 7.6 percent less than the annual average (11.9) since 1960. It is predicted that as the climate warms, severe weather events, such as drought conditions and extreme rainfall, might become more frequent.2
The annual average temperature for 2024 was 55 degrees Fahrenheit (°F), which was above the average annual temperature of approximately 50°F. The number of days with high temperatures greater than 90°F (23) was 52 percent greater than the average from 1960 to present (15.1).
Technical Notes: *Weather data measured at Bradley International Airport (BDL).
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1 National Oceanic and Atmospheric Administration (NOAA), National Weather Service, Hartford-Bradley International Airport, Accessed January 7, 2025; www.weather.gov/wrh/Climate?wfo=box.
2 Connecticut Department of Energy and Environmental Protection (DEEP), BUILDING A LOW CARBON FUTURE FOR CONNECTICUT ACHIEVING A 45% GHG REDUCTION BY 2030; portal.ct.gov/-/media/DEEP/climatechange/publications/BuildingaLowCarbonFutureforCTGC3Recommendationspdf.pdf#page=20.