Data: 2023 USDA zones (PRISM/OSU) · NOAA 1991–2020 normals · updated Oct 29, 2026

Planting zone for 16680 — Smithmill, PA

ZIP code 16680 (Smithmill, Clearfield County) is in USDA zone 6a: the coldest winter night averages −10 to −5 °F. The median last spring frost is May 10 and the first fall frost October 5.

Where ZIP 16680 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.

Zone6a−10 to −5 °F

Coldest night−23.3 to −20.6 °C

Last frostMay 10

First frostOct 5

2012 zone5b

Was 5b on the 2012 map — half a zone warmer now. The zone is the one at the center of the ZIP code; hilly ZIPs can span two zones. What zone 6a means →

Frost forecast — next 7 nights

live from the National Weather Service

Loading the forecast for Smithmill, 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 Smithmill, PA

JanFebMarAprMayJunJulAugSepOctNovDec

Blue: frost possible · fading green: frost risk falling or rising (90% → 10%) · green: frost-free

Last spring frostMay 10median — 50% chance of a later frost

Safe for tender plantsMay 28only 10% chance of frost after

First fall frostOctober 5median — 10% chance by Sep 24

Growing season149 daysfrost-free, median

A hard freeze (28 °F) usually ends around April 29 and returns around October 18.

From the NOAA station Prince Gallitzin Sp, PA — 11 miles away, elevation 1,519 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 16680

JanFebMarAprMayJunJulAugSepOctNovDec

PeasSow outdoors · Mar 29 – Apr 12

SpinachSow outdoors · Mar 29 – Apr 19

Broccoli, cabbageStart indoors · Mar 1 – Mar 15

Broccoli, cabbageTransplant · Apr 19 – May 3

Onion setsPlant outdoors · Apr 12 – Apr 26

PotatoesPlant outdoors · Apr 19 – May 3

LettuceSow outdoors · Apr 12 – Apr 26

Carrots, beetsSow outdoors · Apr 19 – May 3

TomatoesStart indoors · Mar 15 – Mar 29

TomatoesTransplant · May 17 – May 31

Peppers, eggplantStart indoors · Mar 1 – Mar 15

Peppers, eggplantTransplant · May 24 – Jun 7

BeansSow outdoors · May 17 – May 31

Sweet cornSow outdoors · May 17 – May 31

Cucumbers, squashSow outdoors · May 17 – May 31

Fall lettuce, spinachSow outdoors · Aug 10 – Aug 24

GarlicPlant cloves · Sep 21 – Oct 26

Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (May 10) and first fall frost (Oct 5) 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 16680 came on Apr 2 — 7 days earlier than the 1991–2020 average (Apr 9).

average
Apr 92026
Apr 2

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 Smithmill, PA

The soil mapped at the center of ZIP 16680 is Hazleton — channery sandy loam, well drained.

TextureChannery sandy loamdrains and warms fast; dries out and needs more feeding

pH4.5strongly acidic; most vegetables like 6.0–7.0

DrainageWell drainednatural drainage class

Organic matter3%moderate

Hydrologic groupAwater soaks in fast

Farmland classFarmland of statewide importanceUSDA classification

Map unit: Hazleton-Clymer channery loams, 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 16680; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Smithmill, PA

Summer high82 °Faverage high, July

Winter low16 °Faverage low, January

Hot days7days a year at 90 °F or more

Freezing nights154nights a year at 32 °F or less

Growing degree days2,481base 50 °F — the season’s usable heat

Longest day15 h 06 mindaylight on June 21

Shortest day9 h 15 mindaylight on December 21

Onions to growLong-daysummer days reach 15+ hours, enough for long-day varieties (intermediate types work too)

Precipitation43.4 inper year, rain and melted snow

Snowfall35 inper year; 46 days with snow on the ground

Average high and low, by month

Precipitation by month inches · ❄ = snowfall

NOAA NCEI U.S. Climate Normals 1991–2020 — temperature: Prince Gallitzin Sp, PA (11 mi away); precipitation: Tyrone, PA (10 mi away). Daylight is calculated from latitude.

Nearby ZIP codes

All 8 nearest ZIP codes share zone 6a.

Fallentimber, PA · 6 mi

Pennsylvania planting zones →

Questions about 16680

What planting zone is ZIP code 16680?

ZIP code 16680 (Smithmill, PA) is in USDA hardiness zone 6a on the 2023 map: the coldest night of an average winter reaches −10 to −5 °F (−23.3 to −20.6 °C).

When is the last frost in Smithmill, PA?

The median last spring frost (32 °F) near 16680 is May 10; after May 28 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Prince Gallitzin Sp station.

When is the first frost in Smithmill, PA?

The median first fall frost near 16680 is October 5, giving a median frost-free growing season of 149 days.

When should I plant tomatoes in 16680?

Start tomato seeds indoors around Mar 15 – Mar 29 and set transplants outside around May 17 – May 31, one to three weeks after the median last frost.

How much rain and snow does 16680 get?

About 43.4 inches of precipitation a year and 35 inches of snowfall (NOAA 1991–2020 normals, Tyrone station).

How hot do summers get in Smithmill, PA?

The average high peaks at 82 °F in July, with about 7 days a year at 90 °F or more.

What kind of soil does 16680 have?

The USDA soil survey maps Hazleton at the center of ZIP 16680: channery sandy loam, well drained, pH about 4.5 (strongly acidic).

Did spring come early in Smithmill, PA in 2026?

Spring leaf-out near 16680 came on Apr 2 in 2026, 7 days earlier than the 1991–2020 average (Apr 9), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Smithmill, PA?

Long-day onions: the longest day near 16680 is 15 h 06 min, so summer days reach 15+ hours, enough for long-day varieties (intermediate types work too).

Did the zone for 16680 change?

Yes. The 2012 USDA map put 16680 in zone 5b; the 2023 map puts it in zone 6a. The newer map uses 1991–2020 data and more weather stations.