ct mirror

First frosts in Connecticut have arrived anywhere between September and mid-November over the last 23 years, with 79.3% of them arriving in October, according to an analysis of five weather stations across the state.

Much of the greater Hartford area saw its first frost of the year this week, a little later than normal.

But as of the end of October, the temperature had dropped to 32°F just once: in the Bakerville section of New Hartford on Oct. 24. Then temperatures rose again. Detailed data for the first few days of November for the five selected weather stations was not yet available from the National Oceanic and Atmospheric Administration’s daily weather summaries.

Last year, Bakerville saw its first frost as early as Oct. 9, and in 2020 on Sept. 21. In 2021, though, first frost came as late as Nov. 2.

And with weather patterns varying across the state, with some coastal towns experiencing warmer temperatures than inland and higher elevations, the arrival of the first frost differs widely.

The latest frost recorded since 2000 out of the stations analyzed was at a weather station in New London, which got a first frost on Nov. 14 of last year. The second-latest frost was also from that station, on Nov. 8, 2016. New London has not had a frost in September at least since 2000, the earliest being on Oct. 9 in 2001.

The earliest frost in the last 23 years came on Sept. 2, 2018, at a weather station in Willimantic. And the second-earliest readings occurred in 2020, when weather stations in Danbury, Willimantic and Bakerville all dipped to freezing on Sept. 21. However, stations in Hartford and New London didn’t see a frost until late October.

Only 6% of all first frosts across the five stations since 2000 were recorded in September.

The weather station at Hartford’s Brainard Airport has not detected a frost in September since at least 2000. In 19 of the years since, the frosts have occurred in October, but this year, the coldest temperature recorded at the station as of Oct. 28 was 37°F. In 2010, 2017, 2019 and 2021, the temperature at Brainard didn’t drop to freezing until November.

José is CT Mirror's data reporter, reporting data-driven stories and integrating data visualizations into his colleagues' stories. Prior to joining CT Mirror he spent the summer of 2022 at the Wall Street Journal as an investigative data intern. Prior to that, José held internships or fellowships with Texas Tribune, American Public Media Group, ProPublica, Bloomberg and the Knight Center for Journalism in the Americas. A native of Houston, he graduated from the University of Texas with a degree in journalism.