Bield:Farm
Frost date probability · Pennsylvania

Montour County Frost Dates.
Probability table.

The median last spring frost in Montour County is April 14. The median first fall frost is November 1, giving a typical growing season of 201 days.

USDA Zone 6b12.5 mi to NOAA station30-yr record (1991–2020)
High-confidence data

Data from LEWISBURG, PA US, 12.5 miles away with 30-year NOAA record (1991-2020).

Source: LEWISBURG, PA US12.5 mi from county centroid19912020 record (30+ yrs)500 ft elevation
Annual overview

The frost year, at a glance.

Annual frost timeline · Montour County
SAFE TO PLANTApr 28HARVEST BYOct 17Apr 14MEDIAN LAST FROSTNov 1MEDIAN FIRST FROSTJanFebMarAprMayJunJulAugSepOctNovDec
Frost-risk window Median growing season 50% probability
Probability tables

Pick your row by your appetite for risk.

Five risk tiers across three temperature thresholds. Most farmers plan against the conservative side for high-value transplants and the median for direct-seed crops. The aggressive rows are useful when paired with row cover or other season-extension tools.

Last Spring Frost

The range of last-frost dates seen across 1991–2020 at the killing-freeze (28°F) threshold and at the lighter 32°F and harder 24°F thresholds. For frost-sensitive transplants in Montour County, the "very conservative" row is the date frost has occurred at in only 1 of 10 historical years — i.e., the safe-side bound.

Risk tier
28°F killing
32°F light
24°F hard
Very conservative1-in-10 worst year
Apr 28
May 11
Apr 15
Conservative2-in-10 worst years
Apr 23
May 5
Apr 10
Median50% probability
Apr 14
Apr 26
Apr 2
Aggressive8-in-10 best years
Apr 4
Apr 17
Mar 23
Very aggressive1-in-10 best year
Mar 31
Apr 13
Mar 17

Reading: pick a row by your appetite for risk. Very conservative — the unluckiest 10% of years had frost past this date. Very aggressive — only the luckiest 10% of years were frost-free this early. Plant frost-sensitive transplants on the conservative side.

First Fall Frost

The range of first-frost dates in fall. For frost-sensitive harvests (winter squash, fall tomatoes, pumpkins), the "very conservative" row is the harvest deadline — frost has arrived this early in only 1 of 10 historical years.

Risk tier
28°F killing
32°F light
24°F hard
Very conservative1-in-10 worst year
Oct 17
Oct 5
Oct 31
Conservative2-in-10 worst years
Oct 22
Oct 9
Nov 2
Median50% probability
Nov 1
Oct 20
Nov 11
Aggressive8-in-10 best years
Nov 7
Oct 29
Nov 20
Very aggressive1-in-10 best year
Nov 13
Nov 1
Nov 25

Reading: pick a row by your appetite for risk. Very conservative — frost arrived this early in only the unluckiest 10% of years. Very aggressive — frost held off this late in only the luckiest 10% of years. Schedule frost-sensitive harvests on the conservative side.

Growing Season

Days between the last spring frost (28°F) and first fall frost (28°F). Plan for the shorter end if you're growing long-season crops without season-extension tools.

Short year (10%)
172d
Plan for this if you can't afford a frost-shortened season.
Median year (50%)
201d
Half of historical years gave you at least this much.
Long year (90%)
227d
The upside — a ninth of years run this long or longer.

What this means for your crops

Crop-specific planting and harvest guidance derived from the frost probability data above. Each line uses the actual percentile dates from the nearest NOAA station — not a generic regional rule.

  • Set transplants out after April 28 — that's the conservative bound where only 1 of 10 historical years had a 28°F frost past this date. For unprotected fields, waiting another 7 days for the soil to hold above 60°F gives a stronger start.
  • Peppers are more cold-sensitive than tomatoes. Hold transplants until May 5 — about a week past the conservative last-frost bound — and aim for 65°F+ soil temperature.
  • Direct seed sweet corn after April 23, when soil temperature reliably holds above 55°F. Sweet corn tolerates a light spring frost but won't germinate in cold ground.
  • For Halloween harvest, plant by June 29. That gives 110 days to reach the conservative first-fall-frost date (October 17) — frost has arrived this early in only 1 of 10 historical years, so most pumpkins will finish in time.
  • Potatoes can go in around April 12 — about 2 weeks before the median 32°F last-frost date. The shoots tolerate a light frost; what you need is soil temperature above 45°F.
  • For optimal fall establishment, plant winter wheat around September 20 — six weeks before the median first 28°F freeze (November 1). That window gets the crop tillered before dormancy without pushing it too tall, where Hessian fly is a concern.
  • Clover (cool-season)
    Full Pennsylvania calendar →
    Frost-seed clover in late winter when freeze-thaw cycles are still working the soil — typically 4–6 weeks before May 5. Clover germinates as soils warm and is well-rooted before grass competition kicks in.
  • Winter rye is the most frost-tolerant cereal — plant by October 4, four weeks before the median first 28°F freeze. It can germinate in cool soil and will keep growing whenever temperatures are above freezing through fall.

These dates assume a healthy, well-drained field and standard varieties. Adjust for raised beds, row cover, or short-season varieties as appropriate.

Local variation

Why your farm may differ from these dates.

The dates on this page come from the nearest qualifying NOAA station with a 30-year record. Real frost on a real field is shaped by terrain, water, and the built environment. Read the station data as a regional anchor, then adjust for what you know about your own ground.

  • Elevation
    Higher ground frosts earlier in fall and later in spring. As a rule of thumb, expect roughly a 3–5°F difference in overnight low for every 1,000 feet of elevation change versus the nearest valley station.
  • Cold air drainage
    On clear, calm nights cold air sinks into low spots. Valley bottoms, hollows, and the bottom of orchard rows can frost 2–6 weeks differently than nearby slopes — even within a 100-yard radius. South-facing slopes warm faster in spring than north-facing slopes.
  • Urban and suburban heat
    Pavement, buildings, and irrigation push frost dates later than rural stations report. If your operation sits inside a metro area, the local last-frost date is often 1–3 weeks earlier than what a rural NOAA station shows.
  • Water proximity
    Large lakes, rivers, and especially the coast moderate temperature swings. Sites within a mile of a sizable water body typically see a later last-spring frost and an earlier first-fall frost than inland sites at the same latitude.

For precision frost monitoring, install a personal weather station on the field that matters most. The closer the sensor is to the soil surface where you actually plant, the more useful the data.

Hardiness zone comparison

How this compares to USDA Zone 6b.

USDA Zone 6b measures average annual extreme minimum winter temperature for plant winter hardiness. The frost probability data on this page measures the actual range of last-spring and first-fall frost dates from the nearest NOAA weather station — far more useful for planning annual crop planting and harvest.

USDA Hardiness Zone
Measures the average annual minimum winter temperature. Designed to predict whether a perennial plant survives winter in your location — useful for orchard, vine, and ornamental decisions, but says nothing about when last spring frost arrives or how variable that date is.
Frost probability data
Measures the actual statistical distribution of last-spring and first-fall frost dates from a 30-year NOAA record. Designed for annual-crop planning — when to plant transplants, when to direct-seed, when to expect a hard harvest deadline.
Variability

Plan for variability — not just the median.

The probability table above tells you the range. The median gives you 50/50 odds. The conservative end gives you 9-out-of-10 odds. Within Montour County, the difference between an early year and a late year for last spring frost can be about 28 days. Operations with row cover, low tunnels, or high tunnels can effectively shift the conservative end earlier; operations without protection should plan against the conservative bound.

Source data

The NOAA station behind these dates.

LEWISBURG, PA US
Distance
12.5 miles from county centroid
Elevation
500 ft
Record period
19912020
Network
NOAA Climate Normals
View station on NOAA NCEI →
Cross-validation stations
  • SUNBURY, PA US13.8 mi30-yr record
  • BEAR GAP, PA US16.8 mi30-yr record
  • SELINSGROVE PENN VLY AP, PA US17.8 mi30-yr record