USDA Hardiness Zone 7b
Frost Dates for 37031 — Castalian Springs, Tennessee
NOAA 1991–2020 normals from Bethpage 1 S, TN (560 ft), 6 miles north.
Updated
In Castalian Springs, the last spring frost (32°F) is around April 16 in half of years and has passed by May 2 in nine years out of ten. The first fall frost comes around October 23, as early as October 10 one year in ten, leaving a typical freeze-free season of 189 days (NOAA, Bethpage 1 S, TN).
- Last spring frost
- April 16
- First fall frost
- October 23
- Growing season
- 189 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
- January 18
- Last snow
- February 10
- Winters with snow
- 76%
- Snow per year
- 4.6"
median, 1991–2020
median, 1991–2020
22 of 29 observed
NOAA normal
Frost risk by date in Castalian Springs
Half of springs at Bethpage 1 S, TN see their last 32°F night by April 16; only one in ten is past it by March 31, and one in ten still has one after May 2. Planting tender crops after April 22 leaves a 30% risk of a frost on them, after April 27 20%, and after May 2 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 October 23 in half of years, as early as October 10 one year in ten, and holds off past November 4 one year in ten. A hard freeze of 28°F follows 8 days later, around October 31; in spring the one-in-ten date for 28°F is April 20, 12 days before the 32°F one. The freeze-free season lasts 189 days in a typical year, shorter than at 83% of the 144 Tennessee stations; it reaches 210 days one year in ten and falls short of 170 one year in ten. On average 101 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 28, and return around October 15. Severe cold of 16°F or below comes every winter, usually between December 8 and February 26.
| Low | 90% | 80% | 70% | 60% | 50% | 40% | 30% | 20% | 10% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | Apr 13 | Apr 17 | Apr 21 | Apr 25 | Apr 28 | Apr 30 | May 3 | May 6 | May 11 |
| 32°F | Mar 31 | Apr 6 | Apr 9 | Apr 12 | Apr 16 | Apr 19 | Apr 22 | Apr 27 | May 2 |
| 28°F | Mar 17 | Mar 23 | Mar 28 | Mar 31 | Apr 3 | Apr 5 | Apr 9 | Apr 14 | Apr 20 |
| 24°F | Mar 3 | Mar 10 | Mar 15 | Mar 19 | Mar 24 | Mar 28 | Mar 31 | Apr 3 | Apr 8 |
| 20°F | Feb 17 | Feb 25 | Mar 1 | Mar 5 | Mar 10 | Mar 14 | Mar 17 | Mar 24 | Mar 31 |
| 16°F | Jan 31 | Feb 8 | Feb 15 | Feb 21 | Feb 26 | Mar 1 | Mar 6 | Mar 11 | Mar 17 |
| Low | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | Oct 3 | Oct 6 | Oct 10 | Oct 12 | Oct 15 | Oct 17 | Oct 20 | Oct 23 | Oct 26 |
| 32°F | Oct 10 | Oct 14 | Oct 17 | Oct 21 | Oct 23 | Oct 25 | Oct 28 | Nov 1 | Nov 4 |
| 28°F | Oct 18 | Oct 22 | Oct 25 | Oct 28 | Oct 31 | Nov 2 | Nov 5 | Nov 9 | Nov 15 |
| 24°F | Oct 27 | Nov 1 | Nov 4 | Nov 7 | Nov 10 | Nov 14 | Nov 18 | Nov 24 | Dec 1 |
| 20°F | Nov 5 | Nov 11 | Nov 16 | Nov 20 | Nov 25 | Nov 29 | Dec 3 | Dec 7 | Dec 17 |
| 16°F | Nov 17 | Nov 25 | Dec 1 | Dec 4 | Dec 8 | Dec 13 | Dec 20 | Dec 28 | Jan 3 |
Freeze probabilities 1991–2020 at Bethpage 1 S, 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 37031 →Compare Castalian Springs with another place →
Weather by month in Castalian Springs
July is the warmest month at Bethpage 1 S, TN, averaging 88°F by day and 67°F at night; January is the coldest at 45°F and 25°F. A freezing night is all but certain in every month from November to March (a 90% chance or more). From June to September the chance of a 32°F night stays under 10% each month. In spring, April still brings one in 89% of years and May still brings one in 12% of years.
Warmth for growing adds up to 4,093 growing degree days a year (base 50°F), fewer than at 77% of the 144 Tennessee stations. 37% of them (1,515) have built up by the end of June, and July adds the most, 842. Precipitation totals 54.9 inches a year, most in May (5.7") and least in September (3.7"); May to September bring 42% of it.
| Month | High °F | Low °F | Precip. in | 32°F night | Nights ≤ 32°F | GDD 50°F |
|---|---|---|---|---|---|---|
| Jan | 45 | 25 | 4.4 | 100% | 23 | 17 |
| Feb | 50 | 28 | 4.7 | 100% | 20 | 23 |
| Mar | 59 | 34 | 4.9 | 100% | 14 | 79 |
| Apr | 69 | 43 | 5.2 | 89% | 4 | 221 |
| May | 77 | 53 | 5.7 | 12% | <1 | 472 |
| Jun | 84 | 62 | 4.6 | 0% | 0 | 702 |
| Jul | 88 | 67 | 5.2 | 0% | 0 | 842 |
| Aug | 87 | 65 | 3.8 | 0% | 0 | 804 |
| Sep | 82 | 57 | 3.7 | 1% | 0 | 585 |
| Oct | 71 | 44 | 3.8 | 79% | 4 | 261 |
| Nov | 59 | 34 | 3.9 | 100% | 15 | 62 |
| Dec | 49 | 28 | 5.0 | 100% | 21 | 24 |
Monthly normals 1991–2020 at Bethpage 1 S, TN (560 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, Hartsville, TN, 7 miles east of Castalian Springs, has a last frost 4 days earlier (April 12), a first frost 3 days later (October 26), a season 7 days longer.
When it snows in Castalian Springs, Tennessee
The first measurable snow (0.1 inch or more) in Castalian Springs usually arrives around January 18, and the last of the season around February 10. Those are the middle dates across the winters of 1991–2020 at Bethpage 1 S, TN, 5.7 miles away: half of years saw snow earlier, half later. Snow fell in 76% of those winters. The last 32°F night of spring typically comes 65 days after the last snow.
Planting calendar for 37031
| When | What to do |
|---|---|
| February 5 – February 19 | Start peppers and aubergines indoorsThey need eight to ten weeks under lights before they can go out. |
| February 19 – March 5 | Start tomatoes indoorsSix to eight weeks gives a transplant big enough to set fruit early. |
| March 19 – April 2 | Sow peas, spinach, lettuce, radish outdoorsThese tolerate light frost and prefer to germinate in cool soil. |
| April 16 onward | Transplant tomatoes, peppers, basil, squash, cucumbersThe average last freeze has passed — still watch the actual forecast. |
| by July 31 | Sow the autumn crop of carrots, beets and brassicasThey need about twelve weeks to size up before growth stops. |
| by October 9 | Harvest tender crops, or be ready to cover themA first freeze two weeks early is well within normal variation. |
| October 23 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 37031 is 6 miles from Bethpage 1 S, TN, which stands at 560 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 37066 (Gallatin). The 2023 USDA Plant Hardiness Zone Map lists ZIP 37031 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.