USDA Hardiness Zone 8a
Frost Dates for 38068 — Somerville, Tennessee
NOAA 1991–2020 normals from Ames Plantation, TN (460 ft), 13 miles southeast.
Updated
In Somerville, the last spring frost (32°F) is around April 1 in half of years and has passed by April 17 in nine years out of ten. The first fall frost comes around November 3, as early as October 21 one year in ten, leaving a typical freeze-free season of 217 days (NOAA, Ames Plantation, TN).
- Last spring frost
- April 1
- First fall frost
- November 3
- Growing season
- 217 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 16
- Last snow
- February 7
- Winters with snow
- 85%
- Snow per year
- 3.4"
median, 1991–2020
median, 1991–2020
17 of 20 observed
NOAA normal
Frost risk by date in Somerville
Half of springs at Ames Plantation, TN see their last 32°F night by April 1; only one in ten is past it by March 12, and one in ten still has one after April 17. Planting tender crops after April 7 leaves a 30% risk of a frost on them, after April 11 20%, and after April 17 10%. The 16 days between the even-odds date and the one-in-ten date is narrower than at 53% of the 144 Tennessee stations behind this site's ZIP pages.
In fall the first 32°F night comes by November 3 in half of years, as early as October 21 one year in ten, and holds off past November 19 one year in ten. A hard freeze of 28°F follows 11 days later, around November 14; in spring the one-in-ten date for 28°F is April 5, 12 days before the 32°F one. The freeze-free season lasts 217 days in a typical year, longer than at 85% of the 144 Tennessee stations; it reaches 243 days one year in ten and falls short of 196 one year in ten. On average 74 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 11 days longer, to about April 12, and return around October 25. Severe cold of 16°F or below comes in 91% of winters, usually between January 2 and February 1.
| Low | 90% | 80% | 70% | 60% | 50% | 40% | 30% | 20% | 10% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | Mar 26 | Apr 2 | Apr 5 | Apr 9 | Apr 12 | Apr 15 | Apr 19 | Apr 22 | Apr 27 |
| 32°F | Mar 12 | Mar 19 | Mar 24 | Mar 29 | Apr 1 | Apr 3 | Apr 7 | Apr 11 | Apr 17 |
| 28°F | Feb 25 | Mar 3 | Mar 8 | Mar 13 | Mar 17 | Mar 21 | Mar 26 | Apr 1 | Apr 5 |
| 24°F | Feb 8 | Feb 18 | Feb 24 | Feb 28 | Mar 4 | Mar 8 | Mar 13 | Mar 18 | Mar 25 |
| 20°F99% of yrs | Jan 20 | Jan 30 | Feb 5 | Feb 12 | Feb 18 | Feb 24 | Feb 28 | Mar 5 | Mar 13 |
| 16°F91% of yrs | Jan 5 | Jan 15 | Jan 21 | Jan 28 | Feb 1 | Feb 7 | Feb 14 | Feb 23 | Mar 2 |
| Low | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | Oct 12 | Oct 16 | Oct 19 | Oct 23 | Oct 25 | Oct 27 | Oct 30 | Nov 2 | Nov 6 |
| 32°F | Oct 21 | Oct 26 | Oct 29 | Nov 1 | Nov 3 | Nov 5 | Nov 9 | Nov 12 | Nov 19 |
| 28°F | Nov 1 | Nov 4 | Nov 8 | Nov 10 | Nov 14 | Nov 18 | Nov 22 | Nov 26 | Dec 3 |
| 24°F | Nov 7 | Nov 13 | Nov 17 | Nov 22 | Nov 27 | Dec 1 | Dec 6 | Dec 13 | Dec 23 |
| 20°F99% of yrs | Nov 15 | Nov 25 | Dec 1 | Dec 9 | Dec 16 | Dec 23 | Dec 29 | Jan 4 | Jan 12 |
| 16°F91% of yrs | Dec 3 | Dec 15 | Dec 24 | Dec 30 | Jan 2 | Jan 6 | Jan 11 | Jan 18 | Jan 26 |
Freeze probabilities 1991–2020 at Ames Plantation, 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 38068 →Compare Somerville with another place →
Weather by month in Somerville
July is the warmest month at Ames Plantation, TN, averaging 91°F by day and 70°F at night; January is the coldest at 50°F and 31°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 52% of years.
Warmth for growing adds up to 5,176 growing degree days a year (base 50°F), more than at 94% of the 144 Tennessee stations. 39% of them (2,028) have built up by the end of June, and July adds the most, 947. Precipitation totals 57.8 inches a year, most in March (5.7") and least in August (3.4"); May to September bring 40% of it.
| Month | High °F | Low °F | Precip. in | 32°F night | Nights ≤ 32°F | GDD 50°F |
|---|---|---|---|---|---|---|
| Jan | 50 | 31 | 4.6 | 100% | 20 | 36 |
| Feb | 55 | 34 | 5.0 | 100% | 15 | 57 |
| Mar | 63 | 41 | 5.7 | 94% | 9 | 164 |
| Apr | 73 | 49 | 5.7 | 52% | 2 | 346 |
| May | 81 | 59 | 5.7 | 0% | 0 | 608 |
| Jun | 88 | 66 | 4.9 | 0% | 0 | 816 |
| Jul | 91 | 70 | 4.9 | 0% | 0 | 947 |
| Aug | 91 | 68 | 3.4 | 0% | 0 | 914 |
| Sep | 86 | 61 | 4.1 | 0% | 0 | 703 |
| Oct | 75 | 50 | 4.1 | 39% | 2 | 394 |
| Nov | 63 | 40 | 4.2 | 97% | 10 | 138 |
| Dec | 53 | 34 | 5.5 | 100% | 17 | 53 |
Monthly normals 1991–2020 at Ames Plantation, TN (460 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, Moscow, TN, 15 miles south of Somerville, has a last frost 3 days earlier (March 29), the same first-frost date, a season 2 days longer.
When it snows in Somerville, Tennessee
The first measurable snow (0.1 inch or more) in Somerville usually arrives around January 16, and the last of the season around February 7. Those are the middle dates across the winters of 1991–2020 at Somerville 10N, TN, 8.2 miles away: half of years saw snow earlier, half later. Snow fell in 85% of those winters. The last 32°F night of spring typically comes 53 days after the last snow.
Planting calendar for 38068
| When | What to do |
|---|---|
| January 21 – February 4 | Start peppers and aubergines indoorsThey need eight to ten weeks under lights before they can go out. |
| February 4 – February 18 | Start tomatoes indoorsSix to eight weeks gives a transplant big enough to set fruit early. |
| March 4 – March 18 | Sow peas, spinach, lettuce, radish outdoorsThese tolerate light frost and prefer to germinate in cool soil. |
| April 1 onward | Transplant tomatoes, peppers, basil, squash, cucumbersThe average last freeze has passed — still watch the actual forecast. |
| by August 11 | Sow the autumn crop of carrots, beets and brassicasThey need about twelve weeks to size up before growth stops. |
| by October 20 | Harvest tender crops, or be ready to cover themA first freeze two weeks early is well within normal variation. |
| November 3 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 38068 is 13 miles from Ames Plantation, TN, which stands at 460 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. The 2023 USDA Plant Hardiness Zone Map lists ZIP 38068 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.