Data: 2023 USDA zones (PRISM/OSU) · NOAA 1991–2020 normals · updated

Planting zone for 17844 — Mifflinburg, PA

ZIP code 17844 (Mifflinburg, Union County) is in USDA zone 6b: the coldest winter night averages −5 to 0 °F. The median last spring frost is April 25 and the first fall frost October 19.

Where ZIP 17844 is

Outlined: the ZIP code area · tap the map for the zone at any spot · scroll or pinch to zoom

Not the official USDA Plant Hardiness Zone Map. Zones come from the 2023 USDA hardiness-zone data by the PRISM Group, Oregon State University; we re-mapped and recolored them. The official map is at planthardiness.ars.usda.gov.

Zone6b−5 to 0 °F
Coldest night−20.6 to −17.8 °C
Last frostApr 25
First frostOct 19
2012 zone6b

Same zone as on the 2012 map. The zone is the one at the center of the ZIP code; hilly ZIPs can span two zones. What zone 6b means →

Frost forecast — next 7 nights

live from the National Weather Service

Loading the forecast for Mifflinburg, PA…

Forecast data: National Weather Service (api.weather.gov), public domain. This is not a warning service — for official frost and freeze warnings see weather.gov.

Frost dates in Mifflinburg, PA

JanFebMarAprMayJunJulAugSepOctNovDec
Blue: frost possible · fading green: frost risk falling or rising (90% → 10%) · green: frost-free
Last spring frostApril 25median — 50% chance of a later frost
Safe for tender plantsMay 11only 10% chance of frost after
First fall frostOctober 19median — 10% chance by Oct 4
Growing season175 daysfrost-free, median

A hard freeze (28 °F) usually ends around April 12 and returns around November 2.

From the NOAA station Laurelton Center, PA — 8 miles away, elevation 801 ft. NOAA NCEI U.S. Climate Normals 1991–2020, 32 °F threshold. Low spots and valleys can freeze later in spring than the station.

When to plant vegetables in 17844

JanFebMarAprMayJunJulAugSepOctNovDec
PeasSow outdoors · Mar 14 – Mar 28
SpinachSow outdoors · Mar 14 – Apr 4
Broccoli, cabbageStart indoors · Feb 14 – Feb 28
Broccoli, cabbageTransplant · Apr 4 – Apr 18
Onion setsPlant outdoors · Mar 28 – Apr 11
PotatoesPlant outdoors · Apr 4 – Apr 18
LettuceSow outdoors · Mar 28 – Apr 11
Carrots, beetsSow outdoors · Apr 4 – Apr 18
TomatoesStart indoors · Feb 28 – Mar 14
TomatoesTransplant · May 2 – May 16
Peppers, eggplantStart indoors · Feb 14 – Feb 28
Peppers, eggplantTransplant · May 9 – May 23
BeansSow outdoors · May 2 – May 16
Sweet cornSow outdoors · May 2 – May 16
Cucumbers, squashSow outdoors · May 2 – May 16
Fall lettuce, spinachSow outdoors · Aug 24 – Sep 7
GarlicPlant cloves · Oct 5 – Nov 9
Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (Apr 25) and first fall frost (Oct 19) with the rules of thumb U.S. extension services publish. Cool-season crops take a light frost; warm-season crops do best once the soil is above about 60 °F.

When spring arrived in 2026

In 2026, spring leaf-out near 17844 came on Apr 1 — 6 days earlier than the 1991–2020 average (Apr 7).

JanFebMarAprMayJun

The Spring Index marks the day when accumulated warmth is enough for lilac and honeysuckle to leaf out — a widely used signal that the growing season has started. Source: USA National Phenology Network, www.usanpn.org — Spring Indices, first leaf, 2026 (data as of 2026-09-08) and 30-year average 1991–2020 (CC BY 4.0).

Soil in Mifflinburg, PA

The soil mapped at the center of ZIP 17844 is Weikert — channery silt loam, somewhat excessively drained.

TextureChannery silt loama good balance for most vegetables
pH5.0strongly acidic; most vegetables like 6.0–7.0
DrainageSomewhat excessively drainednatural drainage class
Organic matter2.5%moderate
Hydrologic groupDwater soaks in very slowly
Farmland classNot prime farmlandUSDA classification

Map unit: Weikert channery silt loam, 8 to 15 percent slopes.

Soil Survey Staff, Natural Resources Conservation Service, USDA. Soil Survey Geographic (SSURGO) Database, via Soil Data Access, accessed 2026-10-29. The soil at the center point of ZIP 17844; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Mifflinburg, PA

Summer high85 °Faverage high, July
Winter low21 °Faverage low, January
Hot days24days a year at 90 °F or more
Freezing nights142nights a year at 32 °F or less
Growing degree days3,160base 50 °F — the season’s usable heat
Longest day15 h 07 mindaylight on June 21
Shortest day9 h 13 mindaylight on December 21
Onions to growLong-daysummer days reach 15+ hours, enough for long-day varieties (intermediate types work too)
Precipitation45 inper year, rain and melted snow

Average high and low, by month

10°20°30°40°50°60°70°80°90°100°32 °FJanuary: average high 36 °F, low 21 °F 36°21° JanFebruary: average high 41 °F, low 22 °F 41°22° FebMarch: average high 50 °F, low 28 °F 50°28° MarApril: average high 64 °F, low 38 °F 64°38° AprMay: average high 75 °F, low 49 °F 75°49° MayJune: average high 81 °F, low 58 °F 81°58° JunJuly: average high 85 °F, low 62 °F 85°62° JulAugust: average high 84 °F, low 61 °F 84°61° AugSeptember: average high 76 °F, low 54 °F 76°54° SepOctober: average high 65 °F, low 42 °F 65°42° OctNovember: average high 52 °F, low 33 °F 52°33° NovDecember: average high 40 °F, low 26 °F 40°26° Dec

Precipitation by month inches

0″1″2″3″4″5″January: 2.89 in precipitation 2.9 JanFebruary: 2.32 in precipitation 2.3 FebMarch: 3.56 in precipitation 3.6 MarApril: 3.66 in precipitation 3.7 AprMay: 3.90 in precipitation 3.9 MayJune: 4.33 in precipitation 4.3 JunJuly: 4.57 in precipitation 4.6 JulAugust: 4.44 in precipitation 4.4 AugSeptember: 4.70 in precipitation 4.7 SepOctober: 4.14 in precipitation 4.1 OctNovember: 3.25 in precipitation 3.3 NovDecember: 3.28 in precipitation 3.3 Dec

NOAA NCEI U.S. Climate Normals 1991–2020 — temperature: Laurelton Center, PA (8 mi away); precipitation: Mifflinburg 2nw, PA (2 mi away). Daylight is calculated from latitude.

Nearby ZIP codes

All 8 nearest ZIP codes share zone 6b.

178806b
Swengel, PA · 5 mi
178296b
Hartleton, PA · 5 mi
178626b
Penns Creek, PA · 7 mi
178566b
New Columbia, PA · 7 mi
178376b
Lewisburg, PA · 7 mi
178556b
New Berlin, PA · 8 mi
178456b
Millmont, PA · 8 mi
178106b
Allenwood, PA · 10 mi

Pennsylvania planting zones →

Questions about 17844

What planting zone is ZIP code 17844?

ZIP code 17844 (Mifflinburg, PA) is in USDA hardiness zone 6b on the 2023 map: the coldest night of an average winter reaches −5 to 0 °F (−20.6 to −17.8 °C).

When is the last frost in Mifflinburg, PA?

The median last spring frost (32 °F) near 17844 is April 25; after May 11 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Laurelton Center station.

When is the first frost in Mifflinburg, PA?

The median first fall frost near 17844 is October 19, giving a median frost-free growing season of 175 days.

When should I plant tomatoes in 17844?

Start tomato seeds indoors around Feb 28 – Mar 14 and set transplants outside around May 2 – May 16, one to three weeks after the median last frost.

How much rain and snow does 17844 get?

About 45 inches of precipitation a year (NOAA 1991–2020 normals, Mifflinburg 2nw station).

How hot do summers get in Mifflinburg, PA?

The average high peaks at 85 °F in July, with about 24 days a year at 90 °F or more.

What kind of soil does 17844 have?

The USDA soil survey maps Weikert at the center of ZIP 17844: channery silt loam, somewhat excessively drained, pH about 5.0 (strongly acidic).

Did spring come early in Mifflinburg, PA in 2026?

Spring leaf-out near 17844 came on Apr 1 in 2026, 6 days earlier than the 1991–2020 average (Apr 7), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Mifflinburg, PA?

Long-day onions: the longest day near 17844 is 15 h 07 min, so summer days reach 15+ hours, enough for long-day varieties (intermediate types work too).