USDA Hardiness Zone 7b
Frost Dates for 37912 — Knoxville, Tennessee
NOAA 1991–2020 normals from Knoxville Exp Stn, TN (830 ft), 8 miles south.
Updated
In Knoxville, the last spring frost (32°F) is around April 11 in half of years and has passed by April 29 in nine years out of ten. The first fall frost comes around October 28, as early as October 13 one year in ten, leaving a typical freeze-free season of 198 days (NOAA, Knoxville Exp Stn, TN).
- Last spring frost
- April 11
- First fall frost
- October 28
- Growing season
- 198 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 30
- Last snow
- February 22
- Winters with snow
- 96%
- Snow per year
- 4.6"
median, 1991–2020
median, 1991–2020
23 of 24 observed
NOAA normal
Frost risk by date in Knoxville
Half of springs at Knoxville Exp Stn, TN see their last 32°F night by April 11; only one in ten is past it by March 26, and one in ten still has one after April 29. Planting tender crops after April 19 leaves a 30% risk of a frost on them, after April 22 20%, and after April 29 10%. The 18 days between the even-odds date and the one-in-ten date is wider than at 67% of the 144 Tennessee 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 13 one year in ten, and holds off past November 9 one year in ten. A hard freeze of 28°F follows 9 days later, around November 6; in spring the one-in-ten date for 28°F is April 16, 13 days before the 32°F one. The freeze-free season lasts 198 days in a typical year, shorter than at 66% of the 144 Tennessee stations; it reaches 220 days one year in ten and falls short of 176 one year in ten. On average 87 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 24, and return around October 19. Severe cold of 16°F or below comes in 99% of winters, usually between December 25 and February 11.
| Low | 90% | 80% | 70% | 60% | 50% | 40% | 30% | 20% | 10% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | Apr 9 | Apr 14 | Apr 18 | Apr 21 | Apr 24 | Apr 28 | May 1 | May 5 | May 10 |
| 32°F | Mar 26 | Apr 1 | Apr 5 | Apr 8 | Apr 11 | Apr 15 | Apr 19 | Apr 22 | Apr 29 |
| 28°F | Mar 13 | Mar 19 | Mar 24 | Mar 28 | Mar 31 | Apr 2 | Apr 5 | Apr 9 | Apr 16 |
| 24°F | Feb 26 | Mar 5 | Mar 11 | Mar 15 | Mar 18 | Mar 22 | Mar 26 | Mar 31 | Apr 5 |
| 20°F | Feb 4 | Feb 13 | Feb 19 | Feb 25 | Mar 2 | Mar 7 | Mar 12 | Mar 17 | Mar 24 |
| 16°F99% of yrs | Jan 15 | Jan 27 | Feb 1 | Feb 6 | Feb 11 | Feb 17 | Feb 24 | Mar 2 | Mar 11 |
| Low | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | Oct 7 | Oct 11 | Oct 13 | Oct 16 | Oct 19 | Oct 21 | Oct 24 | Oct 27 | Nov 1 |
| 32°F | Oct 13 | Oct 19 | Oct 22 | Oct 25 | Oct 28 | Oct 31 | Nov 1 | Nov 5 | Nov 9 |
| 28°F | Oct 24 | Oct 29 | Nov 1 | Nov 3 | Nov 6 | Nov 9 | Nov 12 | Nov 15 | Nov 20 |
| 24°F | Nov 4 | Nov 8 | Nov 12 | Nov 15 | Nov 18 | Nov 21 | Nov 26 | Dec 1 | Dec 5 |
| 20°F | Nov 15 | Nov 20 | Nov 25 | Nov 29 | Dec 3 | Dec 6 | Dec 13 | Dec 20 | Dec 29 |
| 16°F99% of yrs | Nov 27 | Dec 4 | Dec 11 | Dec 20 | Dec 25 | Dec 30 | Jan 3 | Jan 9 | Jan 19 |
Freeze probabilities 1991–2020 at Knoxville Exp Stn, 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 37912 →Compare Knoxville with another place →
Weather by month in Knoxville
July is the warmest month at Knoxville Exp Stn, TN, averaging 88°F by day and 66°F at night; January is the coldest at 48°F and 26°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 79% of years.
Warmth for growing adds up to 4,278 growing degree days a year (base 50°F), fewer than at 67% of the 144 Tennessee stations. 37% of them (1,599) have built up by the end of June, and July adds the most, 845. Precipitation totals 55.8 inches a year, most in December (5.9") and least in October (3.1"); 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 | 26 | 5.2 | 100% | 22 | 14 |
| Feb | 53 | 29 | 5.1 | 100% | 18 | 23 |
| Mar | 61 | 36 | 5.3 | 100% | 11 | 97 |
| Apr | 71 | 44 | 5.3 | 79% | 3 | 250 |
| May | 79 | 54 | 4.5 | 9% | 0 | 502 |
| Jun | 86 | 62 | 4.0 | 0% | 0 | 712 |
| Jul | 88 | 66 | 5.8 | 0% | 0 | 845 |
| Aug | 88 | 65 | 3.4 | 0% | 0 | 817 |
| Sep | 83 | 59 | 4.1 | 0% | 0 | 622 |
| Oct | 72 | 46 | 3.1 | 63% | 2 | 298 |
| Nov | 61 | 35 | 4.1 | 100% | 13 | 74 |
| Dec | 51 | 30 | 5.9 | 100% | 19 | 23 |
Monthly normals 1991–2020 at Knoxville Exp Stn, TN (830 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, Knoxville Mcghee Tyson Airport, TN, 13 miles south of Knoxville, has a last frost 10 days earlier (April 1), a first frost 5 days later (November 2), a season 17 days longer.
When it snows in Knoxville, Tennessee
The first measurable snow (0.1 inch or more) in Knoxville usually arrives around December 30, and the last of the season around February 22. Those are the middle dates across the winters of 1991–2020 at Knoxville Mcghee Tyson Airport, TN, 13.1 miles away: half of years saw snow earlier, half later. Snow fell in 96% of those winters. The last 32°F night of spring typically comes 48 days after the last snow.
Planting calendar for 37912
| 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 37912 is 8 miles from Knoxville Exp Stn, TN, which stands at 830 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 37918 (Knoxville). The 2023 USDA Plant Hardiness Zone Map lists ZIP 37912 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.
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.