USDA Hardiness Zone 6b
Frost Dates for 66503 — Manhattan, Kansas
NOAA 1991–2020 normals from Tuttle Creek Lake, KS (1,058 ft), 3 miles east.
Updated
In Manhattan, the last spring frost (32°F) is around April 22 in half of years and has passed by May 5 in nine years out of ten. The first fall frost comes around October 20, as early as October 4 one year in ten, leaving a typical freeze-free season of 179 days (NOAA, Tuttle Creek Lake, KS).
- Last spring frost
- April 22
- First fall frost
- October 20
- Growing season
- 179 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 13
- Winters with snow
- 91%
- Snow per year
- —
median, 1991–2020
median, 1991–2020
20 of 22 observed
NOAA normal
Frost risk by date in Manhattan
Half of springs at Tuttle Creek Lake, KS see their last 32°F night by April 22; only one in ten is past it by April 8, and one in ten still has one after May 5. Planting tender crops after April 27 leaves a 30% risk of a frost on them, after April 30 20%, and after May 5 10%. The 13 days between the even-odds date and the one-in-ten date is narrower than at 65% of the 110 Kansas stations behind this site's ZIP pages.
In fall the first 32°F night comes by October 20 in half of years, as early as October 4 one year in ten, and holds off past November 1 one year in ten. A hard freeze of 28°F follows 8 days later, around October 28; in spring the one-in-ten date for 28°F is April 26, 9 days before the 32°F one. The freeze-free season lasts 179 days in a typical year, shorter than at 75% of the 110 Kansas stations; it reaches 198 days one year in ten and falls short of 160 one year in ten. On average 134 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 8 days longer, to about April 30, and return around October 8. Severe cold of 16°F or below comes every winter, usually between November 24 and March 10.
| Low | 90% | 80% | 70% | 60% | 50% | 40% | 30% | 20% | 10% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | Apr 17 | Apr 22 | Apr 26 | Apr 28 | Apr 30 | May 2 | May 5 | May 9 | May 14 |
| 32°F | Apr 8 | Apr 13 | Apr 16 | Apr 19 | Apr 22 | Apr 24 | Apr 27 | Apr 30 | May 5 |
| 28°F | Mar 28 | Apr 2 | Apr 5 | Apr 7 | Apr 10 | Apr 14 | Apr 17 | Apr 21 | Apr 26 |
| 24°F | Mar 14 | Mar 20 | Mar 25 | Mar 29 | Apr 1 | Apr 3 | Apr 6 | Apr 10 | Apr 17 |
| 20°F | Mar 3 | Mar 8 | Mar 12 | Mar 16 | Mar 20 | Mar 25 | Mar 29 | Apr 2 | Apr 6 |
| 16°F | Feb 22 | Feb 28 | Mar 2 | Mar 6 | Mar 10 | Mar 14 | Mar 18 | Mar 22 | Mar 30 |
| Low | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | Sep 25 | Sep 30 | Oct 2 | Oct 5 | Oct 8 | Oct 11 | Oct 14 | Oct 18 | Oct 22 |
| 32°F | Oct 4 | Oct 10 | Oct 14 | Oct 17 | Oct 20 | Oct 22 | Oct 24 | Oct 27 | Nov 1 |
| 28°F | Oct 15 | Oct 19 | Oct 22 | Oct 25 | Oct 28 | Oct 31 | Nov 2 | Nov 5 | Nov 10 |
| 24°F | Oct 23 | Oct 28 | Nov 1 | Nov 3 | Nov 5 | Nov 8 | Nov 12 | Nov 14 | Nov 20 |
| 20°F | Oct 31 | Nov 4 | Nov 7 | Nov 11 | Nov 14 | Nov 17 | Nov 21 | Nov 26 | Dec 1 |
| 16°F | Nov 6 | Nov 12 | Nov 16 | Nov 20 | Nov 24 | Nov 28 | Dec 1 | Dec 5 | Dec 10 |
Freeze probabilities 1991–2020 at Tuttle Creek Lake, KS, 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 66503 →Compare Manhattan with another place →
Weather by month in Manhattan
July is the warmest month at Tuttle Creek Lake, KS, averaging 90°F by day and 67°F at night; January is the coldest at 39°F and 16°F. A freezing night is all but certain in every month from November to April (a 90% chance or more). From June to September the chance of a 32°F night stays under 10% each month. In spring, May still brings one in 19% of years.
Warmth for growing adds up to 3,862 growing degree days a year (base 50°F), fewer than at 79% of the 110 Kansas stations. 35% of them (1,369) have built up by the end of June, and July adds the most, 877. Precipitation totals 33.9 inches a year, most in June (5.3") and least in January (0.6"); May to September bring 64% of it.
| Month | High °F | Low °F | Precip. in | 32°F night | Nights ≤ 32°F | GDD 50°F |
|---|---|---|---|---|---|---|
| Jan | 39 | 16 | 0.6 | 100% | 30 | 1 |
| Feb | 44 | 20 | 1.2 | 100% | 25 | 6 |
| Mar | 55 | 30 | 1.9 | 100% | 19 | 58 |
| Apr | 66 | 41 | 3.3 | 98% | 7 | 175 |
| May | 75 | 52 | 5.1 | 19% | <1 | 424 |
| Jun | 85 | 62 | 5.3 | 0% | 0 | 705 |
| Jul | 90 | 67 | 4.3 | 0% | 0 | 877 |
| Aug | 88 | 65 | 4.2 | 0% | 0 | 815 |
| Sep | 81 | 55 | 2.8 | 5% | <1 | 537 |
| Oct | 68 | 42 | 2.4 | 88% | 5 | 220 |
| Nov | 54 | 30 | 1.6 | 100% | 18 | 41 |
| Dec | 43 | 20 | 1.2 | 100% | 29 | 2 |
Monthly normals 1991–2020 at Tuttle Creek Lake, KS (1,058 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, Manhattan, KS, 5 miles southeast of Manhattan, has a last frost 6 days earlier (April 16), a first frost 1 day earlier (October 19), a season 6 days longer.
When it snows in Manhattan, Kansas
The first measurable snow (0.1 inch or more) in Manhattan usually arrives around December 14, and the last of the season around February 13. Those are the middle dates across the winters of 1991–2020 at Tuttle Creek Lake, KS, 2.7 miles away: half of years saw snow earlier, half later. Snow fell in 91% of those winters. The last 32°F night of spring typically comes 68 days after the last snow.
Planting calendar for 66503
| When | What to do |
|---|---|
| February 11 – February 25 | Start peppers and aubergines indoorsThey need eight to ten weeks under lights before they can go out. |
| February 25 – March 11 | Start tomatoes indoorsSix to eight weeks gives a transplant big enough to set fruit early. |
| March 25 – April 8 | Sow peas, spinach, lettuce, radish outdoorsThese tolerate light frost and prefer to germinate in cool soil. |
| April 22 onward | Transplant tomatoes, peppers, basil, squash, cucumbersThe average last freeze has passed — still watch the actual forecast. |
| by July 28 | Sow the autumn crop of carrots, beets and brassicasThey need about twelve weeks to size up before growth stops. |
| by October 6 | Harvest tender crops, or be ready to cover themA first freeze two weeks early is well within normal variation. |
| October 20 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 66503 is 3 miles from Tuttle Creek Lake, KS, which stands at 1,058 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. The 2023 USDA Plant Hardiness Zone Map lists ZIP 66503 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.