U.S. Frost Dates by Weather Station

NOAA station USC00256290 · Nebraska

Frost Dates for O'Neill, NE

NOAA weather station O'Neill (USC00256290), Nebraska · elevation 1990 ft (607 m) · hardiness zone 5b*

  • Lower-risk planting dateafter May 16only 1 spring in 10 still has a frost later
  • Typical last frostMay 350% chance of a frost after it
  • Typical first fall frostOctober 550% chance of a frost before it
  • Frost-free season155 daystypical year, 32°F
  • Hardiness zone5bcalculated*

The year at a glance

Frost season at O'Neill, NESpring: a frost after April 18 in 9 years out of 10, after May 3 in half of the years, after May 16 in 1 year out of 10. Fall: the first frost comes before September 22 in 1 year out of 10, before October 5 in half of the years, before October 19 in 9 years out of 10. Typical frost-free season: 155 days.JanFebMarAprMayJunJulAugSepOctNovDecLast frost ~May 3First frost ~Oct 5Frost season at O'Neill, NESpring: a frost after April 18 in 9 years out of 10, after May 3 in half of the years, after May 16 in 1 year out of 10. Fall: the first frost comes before September 22 in 1 year out of 10, before October 5 in half of the years, before October 19 in 9 years out of 10. Typical frost-free season: 155 days.JFMAMJJASONDLast frost ~May 3First frost ~Oct 5
frost likely chance fading 90% → 10% frost-free in a typical yearThe year at a glance. Blue: frost is likely; the gradient fades as the chance drops from 90% to 10%; green: the frost-free part of a typical year.

Frost dates (32°F)

Probability of frost, based on 30 years of NOAA records (1991–2020 normals)
ChanceLast frost in spring afterFirst frost in fall before
10% (unlikely)May 16September 22
50% (typical)May 3October 5
90% (likely)April 18October 19
Frost-free season (32°F, 50% chance)
155 days
Hard frost (28°F), last in spring, 50% chance after
April 23
Hard frost (28°F), first in fall, 50% chance before
October 15

The last 15 years (2006–2020 normals)

Typical last frost May 4 (1 day later than the 30-year normal), typical first fall frost October 10 (5 days later). Frost-free season 158 days.

A shorter, more recent NOAA period. The 30-year normals above remain the main reference: 15 years carry more year-to-year noise.

Add these dates to your calendar Yearly reminders for the typical last frost, the lower-risk planting date and the typical first fall frost (.ics).

How the chance of frost changes with the date

Spring at O'Neill: chance of a frost after this dateSpring, chance of a frost after the date: 10% May 16, 20% May 11, 30% May 7, 40% May 5, 50% May 3, 60% May 1, 70% April 28, 80% April 23, 90% April 18. Observed last spring frost in recent years: 2021 May 11, 2022 May 22, 2023 May 3, 2024 April 22, 2025 April 21, 2026 May 7.Spring: last frostChance of a frost after this date10%50%90%May 1May 16May 3Apr 182021: May 112022: May 222023: May 32024: April 222025: April 212026: May 7Fall at O'Neill: chance of a frost before this dateFall, chance of a frost before the date: 10% September 22, 20% September 27, 30% September 29, 40% October 2, 50% October 5, 60% October 8, 70% October 11, 80% October 15, 90% October 19. Observed first fall frost in recent years: 2021 October 14, 2022 October 7, 2023 October 7, 2024 October 14, 2025 October 19.Fall: first frostChance of a frost before this date10%50%90%Oct 1Nov 1Sep 22Oct 5Oct 192021: October 142022: October 72023: October 72024: October 142025: October 19
Two charts, because spring and fall answer different questions: in spring, the chance that a frost still comes after a date; in fall, the chance that the first frost has already come before it. NOAA publishes these odds from 10% to 90%, so the lines stop there. ◆ marks the actual date in each recent year.

What actually happened in recent years

Observed dates of the last spring and first fall frost (32°F) at this station; ◆ marks them on the charts above
YearLast spring frostFirst fall frost
2021May 11October 14
2022May 22October 7
2023May 3October 7
2024April 22October 14
2025April 21October 19
2026May 7season not over yet

What these dates mean

May 16 is the cautious spring light-frost date for O’Neill, carrying only a 10 % chance that a frost will occur later; this gives a gardener the confidence to set out tender crops at that time.

The 50 % light-frost dates are May 3 in spring and October 5 in fall, indicating an even odds of frost around those days but they are not frost thresholds themselves. The 50 % hard-frost dates are April 23 and October 15, marking the points where a 28 °F frost is as likely as not. For a careful autumn schedule, September 22 is the cautious fall light-frost date with only a 10 % chance that frost has already arrived, allowing the completion of tender-crop harvests.

Hard frost at 28 °F can damage plants that would survive a light frost at 32 °F, so it represents a greater risk to tender species.

How to read the probabilities

The dates are probabilities from 30 years of weather, not a forecast for this year.

  • Spring: "10% after May 16" means that in about one spring out of ten a frost still happens after that date. The 90% date is the earliest: a frost after it happens in most years.
  • Fall: "10% before September 22" means that in about one fall out of ten the first frost arrives before that date.
  • 50% is the typical date: half of the years are earlier, half are later.
  • A light frost (32°F) damages tender plants; a hard frost (28°F) also stops most hardy vegetables.

Nearby weather stations

Map of weather stations near O'Neill, NENumbered nearest stations: 1 — Atkinson, NE — 19 mi; 2 — Ewing, NE — 21 mi; 3 — Lynch, NE — 27 mi; 4 — Butte, NE — 33 mi; 5 — Newport, NE — 36 mi.SD25 mi · 40 km1. Atkinson, NE — 19 mi12. Ewing, NE — 21 mi23. Lynch, NE — 27 mi34. Butte, NE — 33 mi45. Newport, NE — 36 mi5
  1. Atkinson, NE 19 mi (31 km)
  2. Ewing, NE 21 mi (34 km)
  3. Lynch, NE 27 mi (44 km)
  4. Butte, NE 33 mi (53 km)
  5. Newport, NE 36 mi (58 km)

Sources

* Hardiness zone 5b: zone derived from PRISM 2023 grid at the station location (not the official USDA map). Source data: PRISM Group, Oregon State University.

Station coordinates: 42.4594, -98.6564.