U.S. Frost Dates by Weather Station

NOAA station USC00253630 · Nebraska

Frost Dates for Hartington, NE

NOAA weather station Hartington (USC00253630), Nebraska · elevation 1408 ft (429 m) · hardiness zone 5b*

  • Lower-risk planting dateafter May 13only 1 spring in 10 still has a frost later
  • Typical last frostApril 3050% chance of a frost after it
  • Typical first fall frostOctober 550% chance of a frost before it
  • Frost-free season159 daystypical year, 32°F
  • Hardiness zone5bcalculated*

The year at a glance

Frost season at Hartington, NESpring: a frost after April 17 in 9 years out of 10, after April 30 in half of the years, after May 13 in 1 year out of 10. Fall: the first frost comes before September 21 in 1 year out of 10, before October 5 in half of the years, before October 20 in 9 years out of 10. Typical frost-free season: 159 days.JanFebMarAprMayJunJulAugSepOctNovDecLast frost ~Apr 30First frost ~Oct 5Frost season at Hartington, NESpring: a frost after April 17 in 9 years out of 10, after April 30 in half of the years, after May 13 in 1 year out of 10. Fall: the first frost comes before September 21 in 1 year out of 10, before October 5 in half of the years, before October 20 in 9 years out of 10. Typical frost-free season: 159 days.JFMAMJJASONDLast frost ~Apr 30First 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 28 years of NOAA records (1991–2020 normals)
ChanceLast frost in spring afterFirst frost in fall before
10% (unlikely)May 13September 21
50% (typical)April 30October 5
90% (likely)April 17October 20
Frost-free season (32°F, 50% chance)
159 days
Hard frost (28°F), last in spring, 50% chance after
April 20
Hard frost (28°F), first in fall, 50% chance before
October 17

The last 15 years (2006–2020 normals)

Typical last frost May 1 (1 day later than the 30-year normal), typical first fall frost October 10 (5 days later). Frost-free season 161 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 Hartington: chance of a frost after this dateSpring, chance of a frost after the date: 10% May 13, 20% May 9, 30% May 5, 40% May 3, 50% April 30, 60% April 28, 70% April 25, 80% April 21, 90% April 17. Observed last spring frost in recent years: 2021 May 12.Spring: last frostChance of a frost after this date10%50%90%May 1May 13Apr 30Apr 172021: May 12Fall at Hartington: chance of a frost before this dateFall, chance of a frost before the date: 10% September 21, 20% September 27, 30% October 1, 40% October 3, 50% October 5, 60% October 9, 70% October 12, 80% October 15, 90% October 20. Observed first fall frost in recent years: 2021 October 22.Fall: first frostChance of a frost before this date10%50%90%Oct 1Nov 1Sep 21Oct 5Oct 202021: October 22
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 12October 22
2022incomplete recordincomplete record
2023no datano data
2024no datano data
2025no datano data
2026no dataseason not over yet

What these dates mean

Setting out tender crops on the early spring date of April 17 carries a 90% chance of a frost, making it a gamble for Hartington gardeners. In contrast, the cautious spring date of May 13 is only a 10% risk, offering a more reliable window for sensitive plantings.

The 50% light-frost dates—April 30 in spring and October 5 in fall—mark the point at which a frost is equally likely to occur later (spring) or earlier (fall). Separate from these, the 50% hard-frost dates are April 20 and October 17; because a hard frost at 28 °F can cause more severe damage than a light frost at 32 °F, it is an especially important threshold to watch.

For a cautious plan, Hartington growers should aim to set out tender crops after May 13 in the spring and to finish harvesting them by September 21 in the fall, while keeping an eye on the hard-frost dates as the critical temperature limit.

How to read the probabilities

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

  • Spring: "10% after May 13" 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 21" 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 Hartington, NENumbered nearest stations: 1 — Crofton, NE — 15 mi; 2 — Yankton, SD — 19 mi; 3 — Vermillion, SD — 20 mi; 4 — Wayne, NE — 29 mi; 5 — Wakefield, NE — 32 mi.NEIASD25 mi · 40 km1. Crofton, NE — 15 mi12. Yankton, SD — 19 mi23. Vermillion, SD — 20 mi34. Wayne, NE — 29 mi45. Wakefield, NE — 32 mi5
  1. Crofton, NE 15 mi (23 km)
  2. Yankton, SD 19 mi (30 km)
  3. Vermillion, SD 20 mi (32 km)
  4. Wayne, NE 29 mi (47 km)
  5. Wakefield, NE 32 mi (51 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: 42.6167, -97.2608.