Last frost dates in Delaware
7 NOAA weather stations in Delaware have thirty years of frost records. The median station sees its last 32 °F night around Apr 7; across the state that ranges from Mar 29 to Apr 11, so pick the station nearest you rather than a state-wide figure.
| LEWES | Mar 29 | Apr 9 | Mar 13 | Nov 14 | 231 |
| DOVER | Apr 4 | Apr 17 | Mar 22 | Nov 4 | 214 |
| GEORGETOWN SUSSEX CO AP | Apr 4 | Apr 16 | Mar 22 | Nov 6 | 217 |
| NEWARK AG FARM | Apr 7 | Apr 21 | Mar 26 | Nov 2 | 208 |
| WILMINGTON NEW CASTLE CO AP | Apr 7 | Apr 21 | Mar 26 | Nov 1 | 209 |
| WILMINGTON PORTER RSCH | Apr 7 | Apr 24 | Mar 26 | Nov 4 | 209 |
| GREENWOOD 2NE | Apr 11 | Apr 28 | Mar 29 | Oct 30 | 200 |
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.