Frost dates for U.S. gardeners
When is the last frost, and when can you plant?
Frostplot gives the last spring and first fall frost dates for a U.S. place, with the odds behind them, from the official NOAA climate normals for 1991-2020. Every date names the weather station it comes from, how far away it is and how high it sits.
What an answer looks like
Example: Detroit Metro Airport, Michigan (NOAA station USW00094847, elevation 631 ft,
30 years of records).
Each bold value is the median: half of the years fell on either side of it. Source: NOAA NCEI U.S. Climate Normals 1991-2020.
What every place page shows
Dates with odds
The last spring and first fall frost at 10%, 50% and 90% probability, so you can choose how much risk to take with tender seedlings.
Two thresholds
32°F, a light freeze that kills tomatoes, peppers and basil, and 28°F, a hard freeze that also damages many hardier crops.
The station, openly
The NOAA station behind the dates, its distance and elevation. When the nearest good station is far away or much higher or lower, the page says so.
How to use a frost date
A frost date is not a promise. The median last frost is the day when the odds of one more frost drop to even. Many gardeners wait for the 10% date before setting out frost-tender plants, and use the median for hardier ones. Cool-season crops such as peas, spinach and lettuce can be sown weeks before the last frost; warm-season crops wait until after it.
Local spots differ from the station: valley floors and low ground collect cold air and frost later in spring, while city centers and slopes often stay warmer. Read how the dates are calculated for the details.