USDA Hardiness Zone 7a
Frost Dates for 21713 — Boonsboro, Maryland
NOAA 1991–2020 normals from Hagerstown 1 E, MD (532 ft), 8 miles north.
Updated
In Boonsboro, the last spring frost (32°F) is around April 11 in half of years and has passed by April 27 in nine years out of ten. The first fall frost comes around October 28, as early as October 14 one year in ten, leaving a typical freeze-free season of 199 days (NOAA, Hagerstown 1 E, MD).
- Last spring frost
- April 11
- First fall frost
- October 28
- Growing season
- 199 days
- Hardiness zone
- 7a
50% probability
50% probability
freeze-free, 50%
0 to 5°F (-17.8 to -15.0°C) coldest night
- First snow
- December 9
- Last snow
- March 14
- Winters with snow
- 100%
- Snow per year
- —
median, 1991–2020
median, 1991–2020
30 of 30 observed
NOAA normal
Frost risk by date in Boonsboro
Half of springs at Hagerstown 1 E, MD see their last 32°F night by April 11; only one in ten is past it by March 29, and one in ten still has one after April 27. Planting tender crops after April 17 leaves a 30% risk of a frost on them, after April 21 20%, and after April 27 10%. The 16 days between the even-odds date and the one-in-ten date is wider than at 50% of the 50 Maryland stations behind this site's ZIP pages.
In fall the first 32°F night comes by October 28 in half of years, as early as October 14 one year in ten, and holds off past November 11 one year in ten. A hard freeze of 28°F follows 12 days later, around November 9; in spring the one-in-ten date for 28°F is April 11, 16 days before the 32°F one. The freeze-free season lasts 199 days in a typical year, shorter than at 62% of the 50 Maryland stations; it reaches 219 days one year in ten and falls short of 179 one year in ten. On average 103 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 12 days longer, to about April 23, and return around October 18. Severe cold of 16°F or below comes in 99% of winters, usually between December 25 and February 19.
| Low | 90% | 80% | 70% | 60% | 50% | 40% | 30% | 20% | 10% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | Apr 9 | Apr 14 | Apr 17 | Apr 20 | Apr 23 | Apr 26 | Apr 30 | May 3 | May 9 |
| 32°F | Mar 29 | Apr 2 | Apr 5 | Apr 8 | Apr 11 | Apr 14 | Apr 17 | Apr 21 | Apr 27 |
| 28°F | Mar 14 | Mar 20 | Mar 24 | Mar 28 | Mar 31 | Apr 2 | Apr 4 | Apr 7 | Apr 11 |
| 24°F | Feb 28 | Mar 6 | Mar 11 | Mar 15 | Mar 17 | Mar 22 | Mar 25 | Mar 29 | Apr 2 |
| 20°F | Feb 11 | Feb 21 | Feb 27 | Mar 2 | Mar 6 | Mar 10 | Mar 13 | Mar 17 | Mar 22 |
| 16°F99% of yrs | Jan 22 | Feb 1 | Feb 6 | Feb 12 | Feb 19 | Feb 25 | Mar 1 | Mar 7 | Mar 14 |
| Low | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | Oct 5 | Oct 9 | Oct 12 | Oct 15 | Oct 18 | Oct 21 | Oct 24 | Oct 27 | Oct 31 |
| 32°F | Oct 14 | Oct 19 | Oct 23 | Oct 26 | Oct 28 | Oct 31 | Nov 2 | Nov 5 | Nov 11 |
| 28°F | Oct 26 | Oct 31 | Nov 3 | Nov 6 | Nov 9 | Nov 12 | Nov 15 | Nov 19 | Nov 25 |
| 24°F | Nov 6 | Nov 11 | Nov 15 | Nov 19 | Nov 23 | Nov 27 | Dec 1 | Dec 4 | Dec 11 |
| 20°F | Nov 20 | Nov 27 | Dec 1 | Dec 5 | Dec 8 | Dec 14 | Dec 18 | Dec 23 | Jan 1 |
| 16°F99% of yrs | Dec 4 | Dec 10 | Dec 16 | Dec 21 | Dec 25 | Dec 31 | Jan 2 | Jan 10 | Jan 18 |
Freeze probabilities 1991–2020 at Hagerstown 1 E, 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 21713 →Compare Boonsboro with another place →
Compared with the next station
The nearest other station, Sharpsburg 5 S, MD, 9 miles south of Boonsboro, has a last frost 15 days later (April 26), a first frost 10 days earlier (October 18), a season 24 days shorter.
When it snows in Boonsboro, Maryland
The first measurable snow (0.1 inch or more) in Boonsboro usually arrives around December 9, and the last of the season around March 14. Those are the middle dates across the winters of 1991–2020 at Hagerstown 1 E, MD, 8.4 miles away: half of years saw snow earlier, half later. Every one of those winters saw snow. The last 32°F night of spring typically comes 28 days after the last snow.
Planting calendar for 21713
| When | What to do |
|---|---|
| January 31 – February 14 | Start peppers and aubergines indoorsThey need eight to ten weeks under lights before they can go out. |
| February 14 – February 28 | Start tomatoes indoorsSix to eight weeks gives a transplant big enough to set fruit early. |
| March 14 – March 28 | Sow peas, spinach, lettuce, radish outdoorsThese tolerate light frost and prefer to germinate in cool soil. |
| April 11 onward | Transplant tomatoes, peppers, basil, squash, cucumbersThe average last freeze has passed — still watch the actual forecast. |
| by August 5 | Sow the autumn crop of carrots, beets and brassicasThey need about twelve weeks to size up before growth stops. |
| by October 14 | Harvest tender crops, or be ready to cover themA first freeze two weeks early is well within normal variation. |
| October 28 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 21713 is 8 miles from Hagerstown 1 E, MD, which stands at 532 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. 4 other ZIP codes share the station; its figures are presented in full for 21740 (Hagerstown). The 2023 USDA Plant Hardiness Zone Map lists ZIP 21713 in zone 7a, the band where the coldest night of the year averaged 0 to 5°F (-17.8 to -15.0°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.