USDA Hardiness Zone 8a
Frost Dates for 27310 — Oak Ridge, North Carolina
NOAA 1991–2020 normals from Piedmont Triad International Airport, NC (890 ft), 6 miles south.
Updated
In Oak Ridge, the last spring frost (32°F) is around March 30 in half of years and has passed by April 14 in nine years out of ten. The first fall frost comes around November 5, as early as October 25 one year in ten, leaving a typical freeze-free season of 220 days (NOAA, Piedmont Triad International Airport, NC).
- Last spring frost
- March 30
- First fall frost
- November 5
- Growing season
- 220 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 9
- Last snow
- February 21
- Winters with snow
- 93%
- Snow per year
- 7.1"
median, 1991–2020
median, 1991–2020
28 of 30 observed
NOAA normal
Frost risk by date in Oak Ridge
Half of springs at Piedmont Triad International Airport, NC see their last 32°F night by March 30; only one in ten is past it by March 12, and one in ten still has one after April 14. Planting tender crops after April 5 leaves a 30% risk of a frost on them, after April 8 20%, and after April 14 10%. The 15 days between the even-odds date and the one-in-ten date is narrower than at 57% of the 173 North Carolina stations behind this site's ZIP pages.
In fall the first 32°F night comes by November 5 in half of years, as early as October 25 one year in ten, and holds off past November 21 one year in ten. A hard freeze of 28°F follows 12 days later, around November 17; in spring the one-in-ten date for 28°F is April 4, 10 days before the 32°F one. The freeze-free season lasts 220 days in a typical year, longer than at 55% of the 173 North Carolina stations; it reaches 243 days one year in ten and falls short of 201 one year in ten. On average 68 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 14 days longer, to about April 13, and return around October 27. Nights of 24°F, cold enough to damage hardier plants, come in 100% of winters and 16°F in 88%.
| Low | 90% | 80% | 70% | 60% | 50% | 40% | 30% | 20% | 10% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | Mar 29 | Apr 3 | Apr 6 | Apr 9 | Apr 13 | Apr 15 | Apr 18 | Apr 22 | Apr 27 |
| 32°F | Mar 12 | Mar 19 | Mar 24 | Mar 27 | Mar 30 | Apr 2 | Apr 5 | Apr 8 | Apr 14 |
| 28°F | Feb 28 | Mar 7 | Mar 11 | Mar 15 | Mar 18 | Mar 22 | Mar 26 | Mar 30 | Apr 4 |
| 24°F | Feb 10 | Feb 19 | Feb 25 | Feb 28 | Mar 4 | Mar 10 | Mar 15 | Mar 19 | Mar 25 |
| 20°F99% of yrs | Jan 23 | Feb 1 | Feb 6 | Feb 12 | Feb 19 | Feb 25 | Mar 1 | Mar 7 | Mar 15 |
| 16°F88% of yrs | Jan 8 | Jan 17 | Jan 24 | Jan 29 | Feb 1 | Feb 6 | Feb 14 | Feb 25 | Mar 6 |
| Low | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | Oct 14 | Oct 18 | Oct 22 | Oct 25 | Oct 27 | Oct 29 | Nov 1 | Nov 3 | Nov 7 |
| 32°F | Oct 25 | Oct 30 | Nov 1 | Nov 3 | Nov 5 | Nov 7 | Nov 11 | Nov 14 | Nov 21 |
| 28°F | Nov 3 | Nov 7 | Nov 11 | Nov 14 | Nov 17 | Nov 21 | Nov 24 | Nov 28 | Dec 4 |
| 24°F | Nov 13 | Nov 18 | Nov 23 | Nov 28 | Dec 2 | Dec 5 | Dec 10 | Dec 18 | Dec 26 |
| 20°F99% of yrs | Nov 27 | Dec 3 | Dec 8 | Dec 14 | Dec 20 | Dec 26 | Dec 31 | Jan 7 | Jan 17 |
| 16°F88% of yrs | Dec 10 | Dec 19 | Dec 28 | Jan 1 | Jan 7 | Jan 13 | Jan 17 | Jan 24 | Feb 2 |
Freeze probabilities 1991–2020 at Piedmont Triad International Airport, NC, 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 27310 →Compare Oak Ridge with another place →
Weather by month in Oak Ridge
July is the warmest month at Piedmont Triad International Airport, NC, averaging 89°F by day and 69°F at night; January is the coldest at 49°F and 30°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 45% of years.
Warmth for growing adds up to 4,622 growing degree days a year (base 50°F), fewer than at 51% of the 173 North Carolina stations. 39% of them (1,786) have built up by the end of June, and July adds the most, 896. Precipitation totals 44.1 inches a year, most in September (4.6") and least in February (2.8"); May to September bring 47% of it.
| Month | High °F | Low °F | Precip. in | 32°F night | Nights ≤ 32°F | GDD 50°F |
|---|---|---|---|---|---|---|
| Jan | 49 | 30 | 3.4 | 100% | 20 | 22 |
| Feb | 53 | 33 | 2.8 | 100% | 15 | 34 |
| Mar | 61 | 39 | 3.7 | 96% | 8 | 125 |
| Apr | 71 | 48 | 3.8 | 45% | 1 | 301 |
| May | 78 | 57 | 3.5 | 0% | 0 | 545 |
| Jun | 85 | 65 | 4.1 | 0% | 0 | 759 |
| Jul | 89 | 69 | 4.2 | 0% | 0 | 896 |
| Aug | 87 | 68 | 4.4 | 0% | 0 | 846 |
| Sep | 80 | 62 | 4.6 | 0% | 0 | 629 |
| Oct | 71 | 49 | 3.1 | 28% | 1 | 327 |
| Nov | 61 | 39 | 3.3 | 99% | 8 | 103 |
| Dec | 52 | 33 | 3.2 | 99% | 17 | 36 |
Monthly normals 1991–2020 at Piedmont Triad International Airport, NC (890 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, Greensboro Wtp, NC, 12 miles southeast of Oak Ridge, has a last frost 2 days later (April 1), a first frost 1 day earlier (November 4), a season 3 days shorter.
When it snows in Oak Ridge, North Carolina
The first measurable snow (0.1 inch or more) in Oak Ridge usually arrives around January 9, and the last of the season around February 21. Those are the middle dates across the winters of 1991–2020 at Piedmont Triad International Airport, NC, 6.1 miles away: half of years saw snow earlier, half later. Snow fell in 93% of those winters. The last 32°F night of spring typically comes 37 days after the last snow.
Planting calendar for 27310
| When | What to do |
|---|---|
| January 19 – February 2 | Start peppers and aubergines indoorsThey need eight to ten weeks under lights before they can go out. |
| February 2 – February 16 | Start tomatoes indoorsSix to eight weeks gives a transplant big enough to set fruit early. |
| March 2 – March 16 | Sow peas, spinach, lettuce, radish outdoorsThese tolerate light frost and prefer to germinate in cool soil. |
| March 30 onward | Transplant tomatoes, peppers, basil, squash, cucumbersThe average last freeze has passed — still watch the actual forecast. |
| by August 13 | Sow the autumn crop of carrots, beets and brassicasThey need about twelve weeks to size up before growth stops. |
| by October 22 | Harvest tender crops, or be ready to cover themA first freeze two weeks early is well within normal variation. |
| November 5 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 27310 is 6 miles from Piedmont Triad International Airport, NC, which stands at 890 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. 5 other ZIP codes share the station; its figures are presented in full for 27410 (Greensboro). The 2023 USDA Plant Hardiness Zone Map lists ZIP 27310 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 North Carolina →
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.