USDA Hardiness Zone 6b
Frost Dates for 47670 — Princeton, Indiana
NOAA 1991–2020 normals from Princeton 1 W, IN (480 ft), 1 miles northwest.
Updated
In Princeton, the last spring frost (32°F) is around April 13 in half of years and has passed by April 30 in nine years out of ten. The first fall frost comes around October 25, as early as October 10 one year in ten, leaving a typical freeze-free season of 194 days (NOAA, Princeton 1 W, IN).
- Last spring frost
- April 13
- First fall frost
- October 25
- Growing season
- 194 days
- Hardiness zone
- 6b
50% probability
50% probability
freeze-free, 50%
-5 to 0°F (-20.6 to -17.8°C) coldest night
- First snow
- December 14
- Last snow
- February 12
- Winters with snow
- 100%
- Snow per year
- 12.2"
median, 1991–2020
median, 1991–2020
20 of 20 observed
NOAA normal
Frost risk by date in Princeton
Half of springs at Princeton 1 W, IN see their last 32°F night by April 13; only one in ten is past it by March 29, and one in ten still has one after April 30. Planting tender crops after April 19 leaves a 30% risk of a frost on them, after April 24 20%, and after April 30 10%. The 17 days between the even-odds date and the one-in-ten date is wider than at 66% of the 125 Indiana stations behind this site's ZIP pages.
In fall the first 32°F night comes by October 25 in half of years, as early as October 10 one year in ten, and holds off past November 6 one year in ten. A hard freeze of 28°F follows 9 days later, around November 3; in spring the one-in-ten date for 28°F is April 18, 12 days before the 32°F one. The freeze-free season lasts 194 days in a typical year, longer than at 78% of the 125 Indiana stations; it reaches 214 days one year in ten and falls short of 171 one year in ten. On average 100 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 24, and return around October 15. Severe cold of 16°F or below comes every winter, usually between December 5 and March 2.
| Low | 90% | 80% | 70% | 60% | 50% | 40% | 30% | 20% | 10% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | Apr 10 | Apr 15 | Apr 18 | Apr 21 | Apr 24 | Apr 28 | May 1 | May 4 | May 9 |
| 32°F | Mar 29 | Apr 2 | Apr 6 | Apr 9 | Apr 13 | Apr 16 | Apr 19 | Apr 24 | Apr 30 |
| 28°F | Mar 16 | Mar 22 | Mar 27 | Mar 30 | Apr 2 | Apr 4 | Apr 8 | Apr 11 | Apr 18 |
| 24°F | Mar 4 | Mar 12 | Mar 16 | Mar 19 | Mar 22 | Mar 26 | Mar 30 | Apr 2 | Apr 7 |
| 20°F | Feb 21 | Mar 1 | Mar 5 | Mar 9 | Mar 13 | Mar 16 | Mar 19 | Mar 23 | Mar 29 |
| 16°F | Feb 7 | Feb 16 | Feb 22 | Feb 28 | Mar 2 | Mar 5 | Mar 8 | Mar 13 | Mar 18 |
| Low | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | Oct 1 | Oct 6 | Oct 9 | Oct 12 | Oct 15 | Oct 18 | Oct 20 | Oct 23 | Oct 27 |
| 32°F | Oct 10 | Oct 17 | Oct 20 | Oct 23 | Oct 25 | Oct 28 | Oct 30 | Nov 2 | Nov 6 |
| 28°F | Oct 20 | Oct 26 | Oct 28 | Nov 1 | Nov 3 | Nov 5 | Nov 8 | Nov 12 | Nov 17 |
| 24°F | Oct 29 | Nov 3 | Nov 6 | Nov 9 | Nov 12 | Nov 15 | Nov 19 | Nov 24 | Dec 1 |
| 20°F | Nov 7 | Nov 12 | Nov 16 | Nov 20 | Nov 24 | Nov 28 | Dec 1 | Dec 6 | Dec 12 |
| 16°F | Nov 15 | Nov 24 | Nov 28 | Dec 1 | Dec 5 | Dec 9 | Dec 15 | Dec 21 | Dec 26 |
Freeze probabilities 1991–2020 at Princeton 1 W, IN, 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 47670 →Compare Princeton with another place →
Weather by month in Princeton
July is the warmest month at Princeton 1 W, IN, averaging 88°F by day and 66°F at night; January is the coldest at 40°F and 21°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 84% of years.
Warmth for growing adds up to 3,980 growing degree days a year (base 50°F), more than at 84% of the 125 Indiana stations. 37% of them (1,470) have built up by the end of June, and July adds the most, 837. Precipitation totals 49.9 inches a year, most in May (5.7") and least in February (3.2"); May to September bring 44% of it.
| Month | High °F | Low °F | Precip. in | 32°F night | Nights ≤ 32°F | GDD 50°F |
|---|---|---|---|---|---|---|
| Jan | 40 | 21 | 3.4 | 100% | 25 | 3 |
| Feb | 45 | 24 | 3.2 | 100% | 21 | 8 |
| Mar | 55 | 32 | 4.5 | 100% | 14 | 58 |
| Apr | 67 | 43 | 5.3 | 84% | 3 | 203 |
| May | 77 | 54 | 5.7 | 10% | <1 | 472 |
| Jun | 85 | 63 | 4.5 | 0% | 0 | 726 |
| Jul | 88 | 66 | 4.5 | 0% | 0 | 837 |
| Aug | 87 | 64 | 3.3 | 0% | 0 | 797 |
| Sep | 81 | 57 | 4.2 | 1% | 0 | 565 |
| Oct | 69 | 45 | 3.4 | 73% | 1 | 252 |
| Nov | 55 | 33 | 4.1 | 100% | 13 | 52 |
| Dec | 44 | 26 | 3.8 | 100% | 22 | 8 |
Monthly normals 1991–2020 at Princeton 1 W, IN (480 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, Mt Carmel, IL, 11 miles northwest of Princeton, has a last frost 11 days earlier (April 2), a first frost 6 days later (October 31), a season 15 days longer.
When it snows in Princeton, Indiana
The first measurable snow (0.1 inch or more) in Princeton usually arrives around December 14, and the last of the season around February 12. Those are the middle dates across the winters of 1991–2020 at Princeton 1 W, IN, 1 miles away: half of years saw snow earlier, half later. Every one of those winters saw snow. The last 32°F night of spring typically comes 60 days after the last snow.
Planting calendar for 47670
| When | What to do |
|---|---|
| February 2 – February 16 | Start peppers and aubergines indoorsThey need eight to ten weeks under lights before they can go out. |
| February 16 – March 2 | Start tomatoes indoorsSix to eight weeks gives a transplant big enough to set fruit early. |
| March 16 – March 30 | Sow peas, spinach, lettuce, radish outdoorsThese tolerate light frost and prefer to germinate in cool soil. |
| April 13 onward | Transplant tomatoes, peppers, basil, squash, cucumbersThe average last freeze has passed — still watch the actual forecast. |
| by August 2 | Sow the autumn crop of carrots, beets and brassicasThey need about twelve weeks to size up before growth stops. |
| by October 11 | Harvest tender crops, or be ready to cover themA first freeze two weeks early is well within normal variation. |
| October 25 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 47670 is 1 mile from Princeton 1 W, IN, which stands at 480 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. 1 other ZIP code shares the station. The 2023 USDA Plant Hardiness Zone Map lists ZIP 47670 in zone 6b, the band where the coldest night of the year averaged -5 to 0°F (-20.6 to -17.8°C) over 1991–2020; a zone describes winter lows, not frost dates.
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.