Mobile, AL Frost Dates: Last Spring and First Fall Frost

Mobile gardeners can count on February 21 as the even-odds date for the last spring frost and December 6 as the even-odds date for the first fall frost, which adds up to 292 days without a freeze in a typical year.

Put March 15 and November 15 on the calendar as well. A spring freeze after the first of them, or a fall freeze before the second, happens in only one year out of ten, so those dates cover nine years in ten. Compared with the 100-city median of 229 days, Mobile gets 63 days extra before frost returns.

The numbers belong to Mobile Downtown AP, NOAA station USW00013838, which sits 3.7 miles south-east of the Census Bureau's internal point for Mobile at an elevation of about 30 feet.

Mobile's last spring frost, by chance

Read the table from the top: a freeze on or after March 15 is a one-in-ten spring, after February 21 is a coin toss, and after January 25 is the usual case.

The earliest and latest of these dates are 49 days apart, wider than for most of the 100 cities here. A freeze can still come 22 days after the typical date in Mobile, which is why the late date matters more here than in most places.

When is the first frost in Mobile?

NOAA's early fall date for Mobile is November 15, its even-odds date is December 6 and its late date is January 5; the first freeze has come by each of them in one, five and nine years out of ten.

The fall dates spread over 51 days, wider than for most cities on these pages. One year in ten brings the first freeze 21 days ahead of the typical date.

The growing season in Mobile

Mobile has far more frost-free days than the middle of these pages, and slow crops benefit most, as the planting dates below show. A typical year gives 292 days, but nine years in ten still give at least 257 days; 35 days separate the two, a larger swing than most cities here show, so a crop that needs the full typical season is a gamble in Mobile.

These figures are NOAA's own counts of freeze-free days across its simulated years, which is why they can differ a little from the days between the two typical dates. At Mobile Downtown AP a night at or below 32°F turns up in 99.7% of years, which means these dates apply every winter.

When a hard freeze reaches Mobile

Light frost and hard freeze are well separated in Mobile. In fall the typical 28°F night comes on December 30, 24 days after the first 32°F frost on December 6; in spring the last one comes on February 2, 19 days before the last 32°F frost. Crops that tolerate light frost have that stretch to themselves. One spring in ten still has a 28°F night on or after March 6, and one fall in ten sees the first by November 30.

What this means for planting in Mobile

The University of New Hampshire Extension sheet times each crop from the last frost. For Mobile's typical date, February 21, that means cabbage on January 24, lettuce from January 24 to January 31, seed potatoes from February 7 to February 14, and, once the frost is behind you, peppers on March 7 and beans on or after February 21. Peas are the exception to the count: University of New Hampshire Extension says to plant them as soon as the soil thaws, whatever the frost date.

From the late date, March 15, every tender crop moves back 22 days; that buys protection against a spring only one year in ten brings.

Of the 34 crops in the fall planner, 32 still have a July-or-later last planting day in Mobile once NC State Extension's days to harvest and University of Georgia Extension's harvest allowance of 18 days are counted back from frost. The other 2 do not. Of the crops that fit, collard greens is the slowest: 118 days from planting to the early frost, which makes July 20 its last day.

Worked example: the last day for fall broccoli in Mobile

Take fall broccoli in Mobile. NC State Extension lists up to 80 days from transplant to harvest, and University of Georgia Extension adds a harvest allowance of 18 days, so the plants need 98 days before the first frost. Counting back from the typical first frost, December 6, the last planting day is August 30. Counting back from the early date, November 15, it is August 9.

21 days separate the two last days, enough that in Mobile the earlier one is worth following.

Spring is the other end of the same arithmetic: University of New Hampshire Extension sets cabbage-family transplants out two to four weeks before the last frost, which from February 21 puts cabbage out on January 24.

The weather station behind these dates

The nearest usable station stands 3.7 miles south-east of Mobile's internal point, near the city but not in it.

Its elevation is about 30 feet. Of the 100 stations behind these pages, 87 sit higher and 12 lower. In NOAA's file the record is marked S, meaning standard.

Because the Census file has no elevation for Mobile, we cannot say how far your yard is above or below this station. When yours is clearly higher or lower, open the nearby stations in the frost dates tool and favor the colder one.

How Mobile's frost dates compare

Here is how Mobile, with a last frost on February 21 and a first frost on December 6, compares with the three nearest cities on these pages, the closest being New Orleans, LA at 117 miles.

• New Orleans, LA, 117 miles to the west: last frost January 22, first frost January 5, 348 days frost-free; spring frost ends 30 days sooner than in Mobile, and the frost-free season is 56 days longer than Mobile's.
• Columbus, GA, 229 miles to the north-east: last frost March 21, first frost November 11, 238 days frost-free; spring frost lingers 28 days longer than in Mobile, and the season runs 54 days shorter.
• Tallahassee, FL, 230 miles to the east: last frost March 11, first frost November 21, 255 days frost-free; the last frost is 18 days later than in Mobile, and it has 37 days less without frost.

Put the frost dates to work

To go beyond the crops above, use the spring planting planner and fall planting planner, both set to this station. The frost dates tool shows the full odds for Mobile, and the hardiness zone lookup gives the winter-cold zone for your ZIP code.

Looking for another city? The city frost dates index lists every page, grouped by state.

For Alabama, the state planting pages copy the Extension calendar (Alabama Cooperative Extension System) crop by crop and region by region: tomatoes in Alabama, peppers in Alabama, cucumbers in Alabama, summer squash in Alabama, green beans in Alabama. Set those windows beside the frost dates above.

Where these numbers come from

The frost and freeze dates are NOAA's U.S. Climate Normals for 1991–2020 (doi:10.25921/4ek7-fk11), copied from the station's own record without adjustment; NOAA's documentation defines each probability. The city and its internal point come from the Census Bureau's 2024 Gazetteer of places, and the ranking by size from the Census Bureau's Vintage 2024 city and town population estimates, which put Mobile at 201,367 people.

Planting dates here are those rules from University of New Hampshire Extension, NC State Extension and University of Georgia Extension, applied to this station's frost dates and nothing else. See how we source every figure for the checks behind them.

Frost dates are long-term odds, not a forecast. Before you plant, check the local forecast for the coming week, and keep row cover or old sheets handy for the nights the odds get wrong.