Frost dates by ZIP code
Your average first and last frost, from ten years of recorded low temperatures at your coordinates.
What these dates mean
| Last spring frost | The average final freezing night of winter. After it, tender plants can generally go out |
|---|---|
| First fall frost | The average first freezing night of autumn. The deadline for bringing them in |
| Growing season | The frost-free days between the two |
| Method | Ten years of daily minimums at your ZIP's coordinates; the first and last 32°F day of each year, averaged |
Questions
What counts as a frost date?
The first and last day the air temperature reaches 32°F. These are averages across many years — roughly half of years will frost earlier than the date shown, so it is a planning figure rather than a guarantee.
Is frost the same as freeze damage?
No, and for houseplants the difference matters enormously. Frost is 32°F. Most tropical houseplants take damage well before that — a monstera suffers around 40°F and a calathea around 55°F. If you are moving houseplants, the frost date is far too late a deadline.
When should I actually bring plants inside?
Two to three weeks before the average first frost, and earlier for anything tropical. Inspect every plant for pests before it joins your indoor collection — an infestation moving inside in autumn is how it spreads to everything you own.
Why do my frost dates differ from my neighbour's?
Cold air sinks. A low-lying garden can frost several degrees colder than one on a slope a few hundred feet away, and a city centre runs warmer than its suburbs. These figures are for your ZIP's coordinates, not your specific garden.