When Is the First Frost? America's Fall Freeze Keeps Arriving Later
The first fall frost in Chicago now arrives on October 30 — 17 days later than it did in the 1970s. And it isn't just Chicago. In all 21 major US cities we measured from 55 years of NOAA records, every single one now freezes later than it used to.
Here's the short answer to “when is the first frost?” — and why the frost chart taped to your grandparents' garden shed is now wrong. The first fall freeze (the first night that drops to 32°F or below) is arriving markedly later across the United States. We averaged the first-freeze date at each city's primary NOAA station over two 20-year windows — 1970–1989 versus 2006–2025 — and every one of the 21 cities moved later, by an average of about nine days.
The extremes are startling. Chicago and Minneapolis each gained 17 days of frost-free autumn. Detroit gained 14, Philadelphia 13, Nashville and Indianapolis 11. Even the cities that barely budged — Salt Lake City (+2), Atlanta and Washington DC (+3) — still moved in the same direction. Nobody in our data is freezing earlier. Below is the first-freeze date for every city, why the interior of the country is changing fastest, and what a two-week-longer growing season actually means if you garden, suffer through allergy season, or farm.
First Frost Date by City: Then vs. Now
Ranked by how much later the first freeze has shifted. “1970s–80s” is the average first date at or below 32°F over 1970–1989; “2006–25” is the same average for the two most recent decades. The gap on the right is the number of extra frost-free days autumn has gained.
| City | 1970s–80s | 2006–25 | Shift | Region |
|---|---|---|---|---|
| Chicago, ILO'Hare Intl | Oct 13 | Oct 30 | +17 days | Great Lakes |
| Minneapolis, MNMSP Intl | Oct 4 | Oct 21 | +17 days | Upper Midwest |
| Detroit, MIDetroit Metro | Oct 15 | Oct 29 | +14 days | Great Lakes |
| Philadelphia, PAPhila Intl | Nov 2 | Nov 15 | +13 days | Northeast |
| Nashville, TNNashville Intl | Oct 28 | Nov 8 | +11 days | Mid-South |
| Indianapolis, INIndianapolis | Oct 16 | Oct 27 | +11 days | Midwest |
| Milwaukee, WIMitchell AP | Oct 19 | Oct 29 | +10 days | Great Lakes |
| Portland, MEPortland Jetport | Oct 7 | Oct 17 | +10 days | Northeast |
| New York, NYCentral Park | Nov 13 | Nov 22 | +9 days | Northeast |
| Portland, ORPDX | Nov 11 | Nov 20 | +9 days | Pacific NW |
| St. Louis, MOLambert Intl | Oct 26 | Nov 4 | +9 days | Midwest |
| Pittsburgh, PAPittsburgh ASOS | Oct 17 | Oct 26 | +9 days | Appalachia |
| Columbus, OHJohn Glenn Intl | Oct 18 | Oct 27 | +9 days | Midwest |
| Cincinnati, OHCVG | Oct 18 | Oct 26 | +8 days | Ohio Valley |
| Boston, MABoston | Nov 6 | Nov 13 | +7 days | Northeast |
| Akron, OHAkron-Canton AP | Oct 20 | Oct 27 | +7 days | Ohio Valley |
| Seattle, WASea-Tac | Nov 14 | Nov 19 | +5 days | Pacific NW |
| Denver, CODenver-Stapleton | Oct 7 | Oct 11 | +4 days | High Plains |
| Atlanta, GAHartsfield-Jackson | Nov 16 | Nov 19 | +3 days | Southeast |
| Washington, DCReagan National | Nov 18 | Nov 21 | +3 days | Mid-Atlantic |
| Salt Lake City, UTSLC Intl | Oct 25 | Oct 27 | +2 days | Great Basin |
Averaged over 20-year windows so the numbers reflect a genuine climatological shift, not one warm or cold autumn. Every city met the 10-year-minimum data requirement in both windows. You can pull the raw daily record for the biggest movers on our Chicago and Minneapolis city pages.
The Interior Is Changing Fastest — and That's the Real Story
Look at where the biggest shifts cluster and a clean pattern jumps out: the continental interior, especially the Great Lakes and Upper Midwest, is losing its early frosts fastest. Chicago (+17), Minneapolis (+17), Detroit (+14) and Milwaukee (+10) top the list. These are the places with the sharpest, most continental autumns — nothing nearby to buffer the season — so when the baseline warms, the date of that first killing freeze slides most.
At the other end sit the maritime and southern cities that were already slow to freeze: Seattle (+5), Atlanta (+3), Washington DC (+3) and Salt Lake City (+2). The Pacific keeps the Northwest mild into late November regardless, and the Southeast's first freeze was always a mid-November affair, so there was less room to move. The EPA sees the same split at national scale — it finds the growing season has lengthened about 2.2 days per decade in the West versus about one day per decade in the East since 1895. Our city numbers are steeper because they compare two decades a full generation apart and because urban airport stations carry an extra heat-island nudge, but the direction is identical and unanimous.
Why the First Frost Keeps Slipping Later
The first fall freeze is one of the most sensitive fingerprints of a warming climate, and it moves for a simple reason: autumn nights are warming. A first freeze happens when a clear, calm night lets the surface radiate away enough heat to drop the air to 32°F. If Septembers and Octobers start a degree or two warmer, it takes a later, deeper cold snap to reach freezing — so the date drifts into November.
This is the same trend, viewed from the cold end, that we see in the heat data. Summer highs are rising in most cities (we mapped exactly where in the US cities where summer has warmed most since 1990), and the shoulder seasons are stretching to match. The national numbers back it up: the EPA reports that during 1991–2011 the average frost-free season ran about 10 days longer than during 1901–1960, with the last spring frost about three days earlier and the first fall frost about three days later than the long-term average.
What a Later First Frost Actually Means
For gardeners: a longer growing season
A first freeze that arrives two weeks later is two extra weeks of tomatoes, peppers and flowers before you have to cover the beds. It also means the old “plant your fall crops X weeks before first frost” math is off — if you're still using a 1990s frost chart, you're counting back from a date that no longer holds. Warmer falls can also lull perennials into staying active later, leaving them more exposed when a hard freeze finally does arrive fast.
For allergy sufferers: a longer pollen season
The first hard freeze is what finally kills off ragweed and ends fall allergy misery. Push that date later and, by definition, you extend the ragweed pollen window by roughly the same amount — and the shift is largest in the northern US, exactly where the freeze date has moved most.
For agriculture: more growing degree days
A longer frost-free window means more time to mature a crop and, in some regions, room to squeeze in a second planting. But it's double-edged: warmer autumns extend the season for pests and crop diseases too, and a later average can make the occasional early freeze more damaging because fields aren't expecting it.
How to Find Your Own First Frost Date
If your city isn't in the table above, you can reconstruct your own first-freeze history in a couple of minutes. Use our weather-on-this-day lookup to check what the low temperature did on any past date in your town, and watch this fall's cold snaps land in near-real time on our records-broken tracker. For the cold end of the spectrum — where the deepest freezes and lowest temperatures show up — see the coldest cities in America, and for a full breakdown of which states have the mildest and harshest conditions overall, our best-weather-states rankings rank all 50. Everything ties back to our US weather records hub.
The Bookend to the Hottest Day
The first frost is autumn's opening act, and it's the natural bookend to summer's peak. If the growing season is stretching at the cold end, it's also intensifying at the warm end — we found the single hottest day of the year lands in mid-to-late July for most of the country, and every state's hottest July on record shows how many of those records are recent. Later frosts and hotter summers are two readings of the same instrument.
How We Computed This
For each city we selected the densest long-record NOAA GHCN-Daily station near the city center — the primary airport in almost every case, with a few deliberate choices for continuity (New York uses Central Park, Denver uses the long-running Stapleton record, Portland OR uses PDX). Daily minimum temperatures are stored in tenths of a degree Fahrenheit, so a value of 320 equals 32.0°F. For every year we found the first calendar date on or after August 1 with a low at or below 32°F, then averaged that day-of-year across two windows — 1970–1989 and 2006–2025 — requiring at least 10 valid years in each. The “shift” is simply the difference between the two averaged dates. Where a city's nearest long record belongs to a neighboring town, we label it by that station (for example, the Cleveland-area figure uses the Akron-Canton airport record). This is a station-level analysis, not a full state or metro average.
Frequently Asked Questions
When is the first frost of 2026?
It depends on your region, and it now runs later than most frost charts say. Based on 2006–2025 NOAA data, the average first freeze arrives around October 21 in Minneapolis, October 30 in Chicago, November 15 in Philadelphia, and November 19–22 across the mid-Atlantic and Southeast (Atlanta, Washington DC, New York) — all 1 to 2.5 weeks later than the 1970s.
What temperature counts as a frost versus a freeze?
A freeze is a low of 32°F (0°C) or below — the threshold used here. A light frost can form earlier, around 33–36°F, on clear calm nights when surfaces cool faster than the air, so the first visible frost on the lawn often beats the first official freeze by a few days.
Is the first frost getting later?
Yes — in all 21 cities we measured, by an average of about nine days and by 17 days in Chicago and Minneapolis. It matches the EPA finding that the US frost-free season has lengthened roughly two weeks since the early 20th century.
How is the average first frost date calculated?
We took each city's densest long-record NOAA station, found the first date on or after August 1 each year with a low at or below 32°F, and averaged it over 1970–1989 and 2006–2025 (10-year minimum per window). Reported dates are those 20-year averages, not a single year.
Sources & Method
First-freeze climatology: NOAA GHCN-Daily via our database (1970–present), computed as described above. Growing-season and frost-free-season context: US EPA, “Climate Change Indicators: Length of Growing Season” and the National Climate Assessment frost-free-season indicator. Explore records and extremes across the country on our US weather records hub.