Last frost dates in Connecticut
23 NOAA weather stations in Connecticut have thirty years of frost records. The median station sees its last 32 °F night around Apr 25; across the state that ranges from Apr 5 to May 11, so pick the station nearest you rather than a state-wide figure.
| BRIDGEPORT SIKORSKY MEM AP | Apr 5 | Apr 17 | Mar 25 | Nov 6 | 216 |
| GROTON | Apr 8 | Apr 22 | Mar 28 | Nov 2 | 207 |
| NORWICH PUBLIC UTILITY PLT | Apr 14 | Apr 30 | Apr 1 | Oct 24 | 192 |
| GROTON NEW LONDON AP | Apr 16 | Apr 30 | Apr 3 | Oct 28 | 194 |
| HARTFORD BRAINARD FLD | Apr 17 | May 1 | Apr 1 | Oct 26 | 191 |
| NEW HAVEN TWEED AP | Apr 17 | May 1 | Apr 2 | Oct 27 | 193 |
| STAMFORD 5 N | Apr 17 | May 2 | Apr 3 | Oct 23 | 188 |
| MT CARMEL | Apr 18 | May 3 | Apr 5 | Oct 26 | 191 |
| STORRS | Apr 19 | May 3 | Apr 7 | Oct 22 | 186 |
| DANBURY | Apr 20 | May 6 | Apr 7 | Oct 20 | 181 |
| HARTFORD BRADLEY INTL AP | Apr 21 | May 6 | Apr 8 | Oct 16 | 177 |
| ANSONIA 1 NE | Apr 25 | May 10 | Apr 11 | Oct 17 | 175 |
| BURLINGTON | Apr 25 | May 10 | Apr 12 | Oct 18 | 172 |
| MERIDEN MARKHAM MUNI AP | Apr 26 | May 9 | Apr 11 | Oct 16 | 175 |
| WILLIMANTIC WINDHAM AP | Apr 28 | May 11 | Apr 17 | Oct 13 | 167 |
| BARKHAMSTED | Apr 30 | May 15 | Apr 17 | Oct 17 | 168 |
| HAMPTON | Apr 30 | May 11 | Apr 18 | Oct 15 | 167 |
| DANBURY MUNI AP | May 1 | May 16 | Apr 18 | Oct 14 | 166 |
| W THOMPSON LAKE | May 1 | May 17 | Apr 20 | Oct 9 | 161 |
| NORFOLK 2 SW | May 3 | May 17 | Apr 21 | Oct 11 | 161 |
| STAFFORDVILLE | May 7 | May 21 | Apr 23 | Oct 12 | 159 |
| BAKERSVILLE | May 8 | May 22 | Apr 24 | Oct 5 | 151 |
| FALLS VILLAGE | May 11 | May 27 | Apr 27 | Oct 4 | 146 |
How to read the three dates
Average is the date by which, in half of the years between 1991 and 2020, the last 32 °F night had already happened. Safe is later: only one year in ten saw a frost after it, which is the date to set out frost-tender plants such as dahlia tubers and zinnia seedlings. Early is the risky end, with a frost after it in nine years out of ten.
Every figure is for the weather station, not for your garden. A valley bottom, a north slope or a spot near a lake can run a week or two either way. Cities are warmer than the countryside around them.
Where the numbers come from
The dates are NOAA's U.S. Climate Normals for 1991 to 2020, computed by the National Centers for Environmental Information for every station with thirty years of daily minimum temperatures. ZIP codes are matched to the nearest such station within 150 km using U.S. Census Bureau ZIP Code Tabulation Area centroids. Stations that never see a frost, such as much of south Florida, report no date and are left out.