USDA Hardiness Zone 7b
Frost Dates for 21015 — Bel Air, Maryland
NOAA 1991–2020 normals from Aberdeen Phillips Field, MD (57 ft), 9 miles southeast.
Updated
In Bel Air, the last spring frost (32°F) is around April 10 in half of years and has passed by April 30 in nine years out of ten. The first fall frost comes around October 30, as early as October 14 one year in ten, leaving a typical freeze-free season of 201 days (NOAA, Aberdeen Phillips Field, MD).
- Last spring frost
- April 10
- First fall frost
- October 30
- Growing season
- 201 days
- Hardiness zone
- 7b
50% probability
50% probability
freeze-free, 50%
5 to 10°F (-15.0 to -12.2°C) coldest night
- First snow
- December 27
- Last snow
- February 26
- Winters with snow
- 93%
- Snow per year
- —
median, 1991–2020
median, 1991–2020
28 of 30 observed
NOAA normal
Frost risk by date in Bel Air
Half of springs at Aberdeen Phillips Field, MD see their last 32°F night by April 10; only one in ten is past it by March 27, and one in ten still has one after April 30. Planting tender crops after April 17 leaves a 30% risk of a frost on them, after April 22 20%, and after April 30 10%. The 20 days between the even-odds date and the one-in-ten date is wider than at 88% of the 50 Maryland stations behind this site's ZIP pages.
In fall the first 32°F night comes by October 30 in half of years, as early as October 14 one year in ten, and holds off past November 12 one year in ten. A hard freeze of 28°F follows 11 days later, around November 10; in spring the one-in-ten date for 28°F is April 12, 18 days before the 32°F one. The freeze-free season lasts 201 days in a typical year, shorter than at 56% of the 50 Maryland stations; it reaches 221 days one year in ten and falls short of 178 one year in ten. On average 83 nights a year drop to 32°F or below. Nights of 36°F, when frost can still settle on leaves in low, open spots, continue 17 days longer, to about April 27, and return around October 19. Severe cold of 16°F or below comes in 99% of winters, usually between December 29 and February 23.
| Low | 90% | 80% | 70% | 60% | 50% | 40% | 30% | 20% | 10% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | Apr 9 | Apr 15 | Apr 19 | Apr 22 | Apr 27 | Apr 30 | May 3 | May 7 | May 12 |
| 32°F | Mar 27 | Mar 31 | Apr 3 | Apr 6 | Apr 10 | Apr 14 | Apr 17 | Apr 22 | Apr 30 |
| 28°F | Mar 13 | Mar 19 | Mar 23 | Mar 26 | Mar 29 | Mar 31 | Apr 3 | Apr 6 | Apr 12 |
| 24°F | Feb 28 | Mar 6 | Mar 10 | Mar 14 | Mar 18 | Mar 20 | Mar 24 | Mar 28 | Mar 31 |
| 20°F | Feb 14 | Feb 22 | Feb 27 | Mar 3 | Mar 7 | Mar 10 | Mar 14 | Mar 18 | Mar 23 |
| 16°F99% of yrs | Jan 31 | Feb 5 | Feb 10 | Feb 17 | Feb 23 | Feb 27 | Mar 3 | Mar 9 | Mar 15 |
| Low | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | Oct 5 | Oct 11 | Oct 13 | Oct 16 | Oct 19 | Oct 21 | Oct 24 | Oct 28 | Nov 1 |
| 32°F | Oct 14 | Oct 20 | Oct 23 | Oct 27 | Oct 30 | Nov 1 | Nov 3 | Nov 6 | Nov 12 |
| 28°F | Oct 28 | Nov 1 | Nov 4 | Nov 7 | Nov 10 | Nov 13 | Nov 16 | Nov 20 | Nov 27 |
| 24°F | Nov 6 | Nov 12 | Nov 15 | Nov 19 | Nov 24 | Nov 28 | Dec 1 | Dec 5 | Dec 13 |
| 20°F | Nov 18 | Nov 25 | Dec 1 | Dec 3 | Dec 8 | Dec 12 | Dec 17 | Dec 25 | Jan 2 |
| 16°F99% of yrs | Dec 4 | Dec 11 | Dec 17 | Dec 23 | Dec 29 | Jan 2 | Jan 7 | Jan 13 | Jan 21 |
Freeze probabilities 1991–2020 at Aberdeen Phillips Field, MD, from NOAA NCEI U.S. Climate Normals. Where a temperature is reached in fewer than 99.5% of years, the dates describe only the years that reach it. Not a forecast.
Frost risk on any date in 21015 →Compare Bel Air with another place →
Weather by month in Bel Air
July is the warmest month at Aberdeen Phillips Field, MD, averaging 86°F by day and 68°F at night; January is the coldest at 42°F and 25°F. A freezing night is all but certain in every month from November to March (a 90% chance or more). From May to September the chance of a 32°F night stays under 10% each month. In spring, April still brings one in 77% of years.
Warmth for growing adds up to 3,767 growing degree days a year (base 50°F), fewer than at 58% of the 50 Maryland stations. 34% of them (1,295) have built up by the end of June, and July adds the most, 838. Precipitation totals 47.2 inches a year, most in July (4.8") and least in February (2.8"); May to September bring 47% of it.
| Month | High °F | Low °F | Precip. in | 32°F night | Nights ≤ 32°F | GDD 50°F |
|---|---|---|---|---|---|---|
| Jan | 42 | 25 | 3.3 | 100% | 21 | 5 |
| Feb | 44 | 27 | 2.8 | 100% | 19 | 7 |
| Mar | 53 | 33 | 4.1 | 100% | 13 | 37 |
| Apr | 65 | 43 | 3.5 | 77% | 2 | 174 |
| May | 73 | 53 | 4.0 | 9% | 0 | 404 |
| Jun | 82 | 62 | 4.3 | 0% | 0 | 667 |
| Jul | 86 | 68 | 4.8 | 0% | 0 | 838 |
| Aug | 84 | 66 | 4.2 | 0% | 0 | 778 |
| Sep | 78 | 59 | 4.8 | 0% | 0 | 555 |
| Oct | 67 | 47 | 4.2 | 57% | 1 | 234 |
| Nov | 56 | 37 | 3.3 | 100% | 9 | 55 |
| Dec | 46 | 30 | 3.9 | 100% | 18 | 11 |
Monthly normals 1991–2020 at Aberdeen Phillips Field, MD (57 ft), NOAA NCEI. "32°F night": chance of at least one in the month. GDD: growing degree days, base 50°F.
Compared with the next station
The nearest other station, Conowingo Dam, MD, 11 miles northeast of Bel Air, has a last frost 7 days earlier (April 3), a first frost 7 days later (November 6), a season 16 days longer.
When it snows in Bel Air, Maryland
The first measurable snow (0.1 inch or more) in Bel Air usually arrives around December 27, and the last of the season around February 26. Those are the middle dates across the winters of 1991–2020 at Aberdeen Phillips Field, MD, 8.5 miles away: half of years saw snow earlier, half later. Snow fell in 93% of those winters. The last 32°F night of spring typically comes 43 days after the last snow.
Planting calendar for 21015
| When | What to do |
|---|---|
| January 30 – February 13 | Start peppers and aubergines indoorsThey need eight to ten weeks under lights before they can go out. |
| February 13 – February 27 | Start tomatoes indoorsSix to eight weeks gives a transplant big enough to set fruit early. |
| March 13 – March 27 | Sow peas, spinach, lettuce, radish outdoorsThese tolerate light frost and prefer to germinate in cool soil. |
| April 10 onward | Transplant tomatoes, peppers, basil, squash, cucumbersThe average last freeze has passed — still watch the actual forecast. |
| by August 7 | Sow the autumn crop of carrots, beets and brassicasThey need about twelve weeks to size up before growth stops. |
| by October 16 | Harvest tender crops, or be ready to cover themA first freeze two weeks early is well within normal variation. |
| October 30 onward | Plant garlic, mulch beds, lift tender bulbsGarlic wants a cold spell; bare soil loses structure over winter. |
The weeks before and after the 50% dates are general rules of thumb, not NOAA figures; a seed packet gives the timing for each variety.
Where these figures come from
ZIP 21015 is 9 miles from Aberdeen Phillips Field, MD, which stands at 57 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. 12 other ZIP codes share the station; its figures are presented in full for 21014 (Bel Air). The 2023 USDA Plant Hardiness Zone Map lists ZIP 21015 in zone 7b, the band where the coldest night of the year averaged 5 to 10°F (-15.0 to -12.2°C) over 1991–2020; a zone describes winter lows, not frost dates.
Hardiness zone and temperature range: USDA Plant Hardiness Zone Map 2023 (USDA-ARS, Oregon State University), ZIP-code listing, unchanged. °C converted from °F by this site.
Thirty-year averages, not a forecast: check the forecast before planting out. How stations are matched and which pages are offered to search engines: methodology.