USDA Hardiness Zone 8a
Frost Dates for 37341 — Harrison, Tennessee
NOAA 1991–2020 normals from Soddy Daisy-Mowbray Mountain, TN (1,700 ft), 10 miles northwest.
Updated
In Harrison, the last spring frost (32°F) is around April 7 in half of years and has passed by April 28 in nine years out of ten. The first fall frost comes around October 29, as early as October 13 one year in ten, leaving a typical freeze-free season of 203 days (NOAA, Soddy Daisy-Mowbray Mountain, TN).
- Last spring frost
- April 7
- First fall frost
- October 29
- Growing season
- 203 days
- Hardiness zone
- 8a
50% probability
50% probability
freeze-free, 50%
10 to 15°F (-12.2 to -9.4°C) coldest night
- First snow
- January 17
- Last snow
- February 24
- Winters with snow
- 94%
- Snow per year
- 4.3"
median, 1991–2020
median, 1991–2020
15 of 16 observed
NOAA normal
Frost risk by date in Harrison
Half of springs at Soddy Daisy-Mowbray Mountain, TN see their last 32°F night by April 7; only one in ten is past it by March 20, and one in ten still has one after April 28. Planting tender crops after April 15 leaves a 30% risk of a frost on them, after April 20 20%, and after April 28 10%. The 21 days between the even-odds date and the one-in-ten date is the widest of the 144 Tennessee stations behind this site's ZIP pages, so a fixed calendar date is a gamble here.
In fall the first 32°F night comes by October 29 in half of years, as early as October 13 one year in ten, and holds off past November 12 one year in ten. A hard freeze of 28°F follows 10 days later, around November 8; in spring the one-in-ten date for 28°F is April 13, 15 days before the 32°F one. The freeze-free season lasts 203 days in a typical year, shorter than at 52% of the 144 Tennessee stations; it reaches 229 days one year in ten and falls short of 178 one year in ten. On average 82 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 13 days longer, to about April 20, and return around October 20. Severe cold of 16°F or below comes in 97% of winters, usually between January 1 and February 15.
| Low | 90% | 80% | 70% | 60% | 50% | 40% | 30% | 20% | 10% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | Apr 2 | Apr 8 | Apr 13 | Apr 17 | Apr 20 | Apr 24 | Apr 29 | May 2 | May 8 |
| 32°F | Mar 20 | Mar 27 | Mar 31 | Apr 3 | Apr 7 | Apr 11 | Apr 15 | Apr 20 | Apr 28 |
| 28°F | Mar 6 | Mar 14 | Mar 19 | Mar 23 | Mar 27 | Mar 31 | Apr 2 | Apr 6 | Apr 13 |
| 24°F | Feb 21 | Feb 28 | Mar 5 | Mar 11 | Mar 15 | Mar 19 | Mar 24 | Mar 28 | Apr 2 |
| 20°F | Feb 3 | Feb 12 | Feb 19 | Feb 25 | Mar 1 | Mar 6 | Mar 12 | Mar 17 | Mar 24 |
| 16°F97% of yrs | Jan 17 | Jan 28 | Feb 3 | Feb 8 | Feb 15 | Feb 22 | Feb 28 | Mar 6 | Mar 15 |
| Low | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | Oct 5 | Oct 10 | Oct 14 | Oct 17 | Oct 20 | Oct 22 | Oct 25 | Oct 28 | Nov 2 |
| 32°F | Oct 13 | Oct 19 | Oct 22 | Oct 26 | Oct 29 | Nov 1 | Nov 3 | Nov 7 | Nov 12 |
| 28°F | Oct 23 | Oct 30 | Nov 1 | Nov 5 | Nov 8 | Nov 12 | Nov 16 | Nov 20 | Nov 28 |
| 24°F | Nov 5 | Nov 10 | Nov 15 | Nov 20 | Nov 25 | Nov 29 | Dec 2 | Dec 7 | Dec 16 |
| 20°F | Nov 18 | Nov 27 | Dec 1 | Dec 5 | Dec 11 | Dec 18 | Dec 25 | Jan 1 | Jan 8 |
| 16°F97% of yrs | Dec 3 | Dec 11 | Dec 21 | Dec 27 | Jan 1 | Jan 4 | Jan 8 | Jan 15 | Jan 26 |
Freeze probabilities 1991–2020 at Soddy Daisy-Mowbray Mountain, TN, 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 37341 →Compare Harrison with another place →
Weather by month in Harrison
July is the warmest month at Soddy Daisy-Mowbray Mountain, TN, averaging 88°F by day and 66°F at night; January is the coldest at 48°F and 28°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 65% of years.
Warmth for growing adds up to 4,237 growing degree days a year (base 50°F), fewer than at 69% of the 144 Tennessee stations. 39% of them (1,635) have built up by the end of June, and July adds the most, 828. Precipitation totals 63.1 inches a year, most in December (6.8") and least in October (3.7"); May to September bring 39% of it.
| Month | High °F | Low °F | Precip. in | 32°F night | Nights ≤ 32°F | GDD 50°F |
|---|---|---|---|---|---|---|
| Jan | 48 | 28 | 6.3 | 100% | 21 | 17 |
| Feb | 51 | 31 | 5.0 | 100% | 17 | 25 |
| Mar | 61 | 38 | 5.8 | 98% | 11 | 113 |
| Apr | 71 | 47 | 5.8 | 65% | 3 | 285 |
| May | 78 | 55 | 4.8 | 7% | <1 | 504 |
| Jun | 85 | 62 | 5.3 | 0% | 0 | 691 |
| Jul | 88 | 66 | 4.9 | 0% | 0 | 828 |
| Aug | 87 | 64 | 4.6 | 0% | 0 | 793 |
| Sep | 81 | 57 | 5.0 | 2% | 0 | 580 |
| Oct | 70 | 47 | 3.7 | 56% | 2 | 291 |
| Nov | 59 | 38 | 5.1 | 99% | 9 | 77 |
| Dec | 50 | 32 | 6.8 | 100% | 18 | 34 |
Monthly normals 1991–2020 at Soddy Daisy-Mowbray Mountain, TN (1,700 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, Chattanooga Lovell Airport, TN, 13 miles southwest of Harrison and 1,029 feet lower, has a last frost 14 days earlier (March 24), a first frost 11 days later (November 9), a season 27 days longer.
When it snows in Harrison, Tennessee
The first measurable snow (0.1 inch or more) in Harrison usually arrives around January 17, and the last of the season around February 24. Those are the middle dates across the winters of 1991–2020 at Soddy Daisy-Mowbray Mountain, TN, 10.1 miles away: half of years saw snow earlier, half later. Snow fell in 94% of those winters. The last 32°F night of spring typically comes 42 days after the last snow.
Planting calendar for 37341
| When | What to do |
|---|---|
| January 27 – February 10 | Start peppers and aubergines indoorsThey need eight to ten weeks under lights before they can go out. |
| February 10 – February 24 | Start tomatoes indoorsSix to eight weeks gives a transplant big enough to set fruit early. |
| March 10 – March 24 | Sow peas, spinach, lettuce, radish outdoorsThese tolerate light frost and prefer to germinate in cool soil. |
| April 7 onward | Transplant tomatoes, peppers, basil, squash, cucumbersThe average last freeze has passed — still watch the actual forecast. |
| by August 6 | Sow the autumn crop of carrots, beets and brassicasThey need about twelve weeks to size up before growth stops. |
| by October 15 | Harvest tender crops, or be ready to cover themA first freeze two weeks early is well within normal variation. |
| October 29 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 37341 is 10 miles from Soddy Daisy-Mowbray Mountain, TN, which stands at 1,700 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. 3 other ZIP codes share the station; its figures are presented in full for 37343 (Hixson). The 2023 USDA Plant Hardiness Zone Map lists ZIP 37341 in zone 8a, the band where the coldest night of the year averaged 10 to 15°F (-12.2 to -9.4°C) over 1991–2020; a zone describes winter lows, not frost dates.
Frost dates across Tennessee →
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.