U.S. Frost Dates by Weather Station

NOAA station USC00253605 · Nebraska

Frost Dates for Harrisburg, NE

NOAA weather station Harrisburg 12 WNW (USC00253605), Nebraska · elevation 4550 ft (1387 m) · hardiness zone 5a*

  • Lower-risk planting dateafter June 12only 1 spring in 10 still has a frost later
  • Typical last frostMay 2450% chance of a frost after it
  • Typical first fall frostSeptember 2050% chance of a frost before it
  • Frost-free season117 daystypical year, 32°F
  • Hardiness zone5acalculated*

The year at a glance

Frost season at Harrisburg, NESpring: a frost after May 11 in 9 years out of 10, after May 24 in half of the years, after June 12 in 1 year out of 10. Fall: the first frost comes before September 6 in 1 year out of 10, before September 20 in half of the years, before October 3 in 9 years out of 10. Typical frost-free season: 117 days.JanFebMarAprMayJunJulAugSepOctNovDecLast frost ~May 24First frost ~Sep 20Frost season at Harrisburg, NESpring: a frost after May 11 in 9 years out of 10, after May 24 in half of the years, after June 12 in 1 year out of 10. Fall: the first frost comes before September 6 in 1 year out of 10, before September 20 in half of the years, before October 3 in 9 years out of 10. Typical frost-free season: 117 days.JFMAMJJASONDLast frost ~May 24First frost ~Sep 20
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)June 12September 6
50% (typical)May 24September 20
90% (likely)May 11October 3
Frost-free season (32°F, 50% chance)
117 days
Hard frost (28°F), last in spring, 50% chance after
May 12
Hard frost (28°F), first in fall, 50% chance before
September 29

The last 15 years (2006–2020 normals)

Typical last frost May 23 (1 day earlier than the 30-year normal), typical first fall frost September 19 (1 day earlier). Frost-free season 117 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 Harrisburg: chance of a frost after this dateSpring, chance of a frost after the date: 10% June 12, 20% June 5, 30% June 2, 40% May 29, 50% May 24, 60% May 21, 70% May 18, 80% May 15, 90% May 11. Observed last spring frost in recent years: 2021 May 31, 2022 June 2, 2023 May 6, 2025 May 22, 2026 May 23.Spring: last frostChance of a frost after this date10%50%90%May 1Jun 1Jun 12May 24May 112021: May 312022: June 22023: May 62025: May 222026: May 23Fall at Harrisburg: chance of a frost before this dateFall, chance of a frost before the date: 10% September 6, 20% September 11, 30% September 14, 40% September 17, 50% September 20, 60% September 22, 70% September 25, 80% September 28, 90% October 3. Observed first fall frost in recent years: 2021 October 1, 2022 September 11, 2023 September 25, 2024 October 1.Fall: first frostChance of a frost before this date10%50%90%Sep 1Oct 1Sep 6Sep 20Oct 32021: October 12022: September 112023: September 252024: October 1
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 31October 1
2022June 2September 11
2023May 6September 25
2024incomplete recordOctober 1
2025May 22incomplete record
2026May 23season not over yet

What these dates mean

September 6 is the cautious fall date in Harrisburg, marking a 10 % chance that a light frost has arrived earlier; gardeners planning to finish harvesting tender crops aim for that day. In spring the cautious date for setting out tender crops is June 12, when only a 10 % chance of a light frost remains later in the season, while the earlier May 11 date carries a 90 % chance and is a gamble.

The 50 % dates—May 24 for spring and September 20 for fall—represent the median point at which a light frost is equally likely to have occurred or not; they are not frost dates but useful reference points. Hard-frost median dates are May 12 in spring and September 29 in fall, and a hard frost at 28 °F can damage plants that survive a light frost at 32 °F, making it a more critical threshold.

How to read the probabilities

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

  • Spring: "10% after June 12" 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 6" 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 Harrisburg, NENumbered nearest stations: 1 — near Scottsbluff, NE — 25 mi; 2 — Bridgeport, NE — 44 mi; 3 — Chugwater, WY — 46 mi; 4 — New Raymer, CO — 49 mi; 5 — Old Fort Laramie, WY — 50 mi.25 mi · 40 km1. near Scottsbluff, NE — 25 mi12. Bridgeport, NE — 44 mi23. Chugwater, WY — 46 mi34. New Raymer, CO — 49 mi45. Old Fort Laramie, WY — 50 mi5
  1. near Scottsbluff, NE 25 mi (40 km)
  2. Bridgeport, NE 44 mi (71 km)
  3. Chugwater, WY 46 mi (73 km)
  4. New Raymer, CO 49 mi (78 km)
  5. Old Fort Laramie, WY 50 mi (81 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: 41.6331, -103.9542.