U.S. Frost Dates by Weather Station

NOAA station USC00253615 · Nebraska

Frost Dates for Harrison, NE

NOAA weather station Harrison (USC00253615), Nebraska · elevation 4850 ft (1478 m) · hardiness zone 5a*

  • Lower-risk planting dateafter June 5only 1 spring in 10 still has a frost later
  • Typical last frostMay 2050% chance of a frost after it
  • Typical first fall frostSeptember 2150% chance of a frost before it
  • Frost-free season121 daystypical year, 32°F
  • Hardiness zone5acalculated*

The year at a glance

Frost season at Harrison, NESpring: a frost after May 8 in 9 years out of 10, after May 20 in half of the years, after June 5 in 1 year out of 10. Fall: the first frost comes before September 4 in 1 year out of 10, before September 21 in half of the years, before October 5 in 9 years out of 10. Typical frost-free season: 121 days.JanFebMarAprMayJunJulAugSepOctNovDecLast frost ~May 20First frost ~Sep 21Frost season at Harrison, NESpring: a frost after May 8 in 9 years out of 10, after May 20 in half of the years, after June 5 in 1 year out of 10. Fall: the first frost comes before September 4 in 1 year out of 10, before September 21 in half of the years, before October 5 in 9 years out of 10. Typical frost-free season: 121 days.JFMAMJJASONDLast frost ~May 20First frost ~Sep 21
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 26 years of NOAA records (1991–2020 normals)
ChanceLast frost in spring afterFirst frost in fall before
10% (unlikely)June 5September 4
50% (typical)May 20September 21
90% (likely)May 8October 5
Frost-free season (32°F, 50% chance)
121 days
Hard frost (28°F), last in spring, 50% chance after
May 9
Hard frost (28°F), first in fall, 50% chance before
October 1

The last 15 years (2006–2020 normals)

Typical last frost May 20 (same as the 30-year normal), typical first fall frost September 21. Frost-free season 121 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 Harrison: chance of a frost after this dateSpring, chance of a frost after the date: 10% June 5, 20% May 31, 30% May 27, 40% May 24, 50% May 20, 60% May 18, 70% May 15, 80% May 12, 90% May 8. Observed last spring frost in recent years: 2021 May 13, 2022 June 1.Spring: last frostChance of a frost after this date10%50%90%May 1Jun 1Jun 5May 20May 82021: May 132022: June 1Fall at Harrison: chance of a frost before this dateFall, chance of a frost before the date: 10% September 4, 20% September 10, 30% September 14, 40% September 18, 50% September 21, 60% September 24, 70% September 26, 80% September 30, 90% October 5. Observed first fall frost in recent years: 2022 October 7.Fall: first frostChance of a frost before this date10%50%90%Sep 1Oct 1Sep 4Sep 21Oct 52022: October 7
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 13incomplete record
2022June 1October 7
2023no datano data
2024no datano data
2025no datano data
2026no dataseason not over yet

What these dates mean

The cautious fall date for finishing the harvest in Harrison is September 4, when there is only a 10 % chance that a light frost has arrived.

For a gardener, the 50 % dates signal the point at which a light frost is equally likely to have occurred later (spring) or earlier (fall); the median light-frost dates are May 20 and September 21. A cautious plan therefore sets out tender crops after the spring cautious date of June 5, which carries a 10 % chance of frost later, and harvests tender crops before the fall cautious date of September 4, which carries a 10 % chance of frost earlier.

A hard frost at 28 °F can injure or kill plants that would otherwise survive a light frost at 32 °F, making the 50 % hard-frost dates of May 9 and October 1 especially relevant.

How to read the probabilities

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

  • Spring: "10% after June 5" 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 4" 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 Harrison, NENumbered nearest stations: 1 — Torrington, WY — 19 mi; 2 — Chadron, NE — 43 mi; 3 — Redbird, WY — 44 mi; 4 — Old Fort Laramie, WY — 48 mi; 5 — Oelrichs, SD — 48 mi.WYNE25 mi · 40 km1. Torrington, WY — 19 mi12. Chadron, NE — 43 mi23. Redbird, WY — 44 mi34. Old Fort Laramie, WY — 48 mi45. Oelrichs, SD — 48 mi5
  1. Torrington, WY 19 mi (31 km)
  2. Chadron, NE 43 mi (69 km)
  3. Redbird, WY 44 mi (70 km)
  4. Old Fort Laramie, WY 48 mi (77 km)
  5. Oelrichs, SD 48 mi (77 km)

Sources

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

Station coordinates: 42.6858, -103.8842.