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

Planting zone for 16621 — Broad Top, PA

ZIP code 16621 (Broad Top, Huntingdon County) is in USDA zone 6b: the coldest winter night averages −5 to 0 °F. The median last spring frost is April 19 and the first fall frost October 28.

Where ZIP 16621 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 19
First frostOct 28
2012 zone6a

Was 6a 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 6b means →

Frost forecast — next 7 nights

live from the National Weather Service

Loading the forecast for Broad Top, 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 Broad Top, PA

JanFebMarAprMayJunJulAugSepOctNovDec
Blue: frost possible · fading green: frost risk falling or rising (90% → 10%) · green: frost-free
Last spring frostApril 19median — 50% chance of a later frost
Safe for tender plantsMay 7only 10% chance of frost after
First fall frostOctober 28median — 10% chance by Oct 12
Growing season191 daysfrost-free, median

A hard freeze (28 °F) usually ends around April 6 and returns around November 9.

From the NOAA station Raystown Lake 2, PA — 9 miles away, elevation 1,001 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 16621

JanFebMarAprMayJunJulAugSepOctNovDec
PeasSow outdoors · Mar 8 – Mar 22
SpinachSow outdoors · Mar 8 – Mar 29
Broccoli, cabbageStart indoors · Feb 8 – Feb 22
Broccoli, cabbageTransplant · Mar 29 – Apr 12
Onion setsPlant outdoors · Mar 22 – Apr 5
PotatoesPlant outdoors · Mar 29 – Apr 12
LettuceSow outdoors · Mar 22 – Apr 5
Carrots, beetsSow outdoors · Mar 29 – Apr 12
TomatoesStart indoors · Feb 22 – Mar 8
TomatoesTransplant · Apr 26 – May 10
Peppers, eggplantStart indoors · Feb 8 – Feb 22
Peppers, eggplantTransplant · May 3 – May 17
BeansSow outdoors · Apr 26 – May 10
Sweet cornSow outdoors · Apr 26 – May 10
Cucumbers, squashSow outdoors · Apr 26 – May 10
Fall lettuce, spinachSow outdoors · Sep 2 – Sep 16
GarlicPlant cloves · Oct 14 – Nov 18
Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (Apr 19) and first fall frost (Oct 28) 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 16621 came on Mar 29 — 7 days earlier than the 1991–2020 average (Apr 5).

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).

Native plants for zone 6b in Pennsylvania

605 plants native to the lower 48 states, recorded in Pennsylvania, and rated by the USDA to survive −5 °F or colder — the bottom of zone 6b. Each links to its USDA PLANTS profile.

Trees 76

American basswood100 ft · blooms late spring · low shade tolerance · to −46 °FAmerican beech80 ft · blooms mid spring · low shade tolerance · to −44 °FAmerican chestnut115 ft · blooms early summer · high shade tolerance · to −33 °FAmerican elm120 ft · blooms early spring · medium shade tolerance · to −46 °FAmerican sycamore100 ft · blooms spring · medium shade tolerance · to −34 °Farborvitae50 ft · blooms mid spring · medium shade tolerance · to −33 °F

Shrubs 122

alderleaf buckthorn3 ft · blooms late spring · low shade tolerance · to −33 °FAllegheny serviceberry35 ft · blooms early spring · low shade tolerance · to −38 °Falternateleaf dogwood25 ft · blooms mid spring · low shade tolerance · to −47 °FAmerican black currant3 ft · blooms early spring · to −46 °FAmerican hazelnut10 ft · blooms spring · medium shade tolerance · to −33 °FAmerican holly40 ft · blooms mid spring · low shade tolerance · to −20 °F

Wildflowers & perennials 209

alkali buttercup1 ft · blooms late spring · low shade tolerance · to −38 °FAmerican bur-reed3 ft · blooms indeterminate · medium shade tolerance · to −33 °FAmerican eelgrass1 ft · blooms mid summer · high shade tolerance · to −33 °FAmerican licorice4 ft · blooms late spring · medium shade tolerance · to −38 °FAmerican lotus3 ft · blooms mid summer · high shade tolerance · to −36 °FAmerican pokeweed7 ft · blooms mid summer · low shade tolerance · to −33 °F

Grasses 173

American beachgrass2.5 ft · blooms spring · high shade tolerance · to −28 °Farctic brome3 ft · blooms early summer · low shade tolerance · to −33 °FAtlantic mannagrass3 ft · blooms summer · low shade tolerance · to −8 °Fautumn bluegrass1.5 ft · blooms late spring · medium shade tolerance · to −8 °Fawlfruit sedge4 ft · blooms mid spring · low shade tolerance · to −38 °FBailey's sedge2.1 ft · blooms late spring · low shade tolerance · to −33 °F

Vines 10

American bittersweet15 ft · blooms spring · low shade tolerance · to −38 °Fdevil's darning needles15 ft · blooms mid summer · medium shade tolerance · to −38 °Ffrost grape83 ft · blooms late spring · medium shade tolerance · to −23 °Fgraybark grape50 ft · blooms late spring · medium shade tolerance · to −8 °Friverbank grape45 ft · blooms late spring · medium shade tolerance · to −33 °Fsummer grape30 ft · blooms late spring · low shade tolerance · to −23 °F

Source: USDA, NRCS. 2026. The PLANTS Database (plants.usda.gov), National Plant Data Team — state distribution, native status and the “Temperature, Minimum” characteristic. Check light, moisture and soil needs before buying; local nurseries and your state native plant society can confirm what thrives in Broad Top, PA.

Soil in Broad Top, PA

The soil mapped at the center of ZIP 16621 is Meckesville — channery silt loam, well drained.

TextureChannery silt loama good balance for most vegetables
pH4.6strongly acidic; most vegetables like 6.0–7.0
DrainageWell drainednatural drainage class
Organic matter2.5%moderate
Hydrologic groupCwater soaks in slowly
Farmland classNot prime farmlandUSDA classification

Map unit: Meckesville very stony silt loam, 3 to 8 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 16621; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Broad Top, PA

Summer high85 °Faverage high, July
Winter low21 °Faverage low, January
Hot days14days a year at 90 °F or more
Freezing nights126nights a year at 32 °F or less
Growing degree days3,189base 50 °F — the season’s usable heat
Longest day15 h 03 mindaylight on June 21
Shortest day9 h 18 mindaylight on December 21
Onions to growLong-daysummer days reach 15+ hours, enough for long-day varieties (intermediate types work too)
Precipitation41.1 inper year, rain and melted snow
Snowfall23 inper year; 21 days with snow on the ground

Average high and low, by month

10°20°30°40°50°60°70°80°90°100°32 °FJanuary: average high 37 °F, low 21 °F 37°21° JanFebruary: average high 40 °F, low 22 °F 40°22° FebMarch: average high 49 °F, low 29 °F 49°29° MarApril: average high 62 °F, low 40 °F 62°40° AprMay: average high 72 °F, low 50 °F 72°50° MayJune: average high 80 °F, low 58 °F 80°58° JunJuly: average high 85 °F, low 63 °F 85°63° JulAugust: average high 84 °F, low 62 °F 84°62° AugSeptember: average high 76 °F, low 55 °F 76°55° SepOctober: average high 64 °F, low 44 °F 64°44° OctNovember: average high 52 °F, low 34 °F 52°34° NovDecember: average high 42 °F, low 27 °F 42°27° Dec

Precipitation by month inches · ❄ = snowfall

0″1″2″3″4″5″January: 2.88 in precipitation, 5.7 in snowfall 2.9❄6 JanFebruary: 2.38 in precipitation, 8.5 in snowfall 2.4❄9 FebMarch: 3.60 in precipitation, 2.3 in snowfall 3.6❄2 MarApril: 3.68 in precipitation 3.7 AprMay: 4.03 in precipitation 4.0 MayJune: 3.67 in precipitation 3.7 JunJuly: 4.47 in precipitation 4.5 JulAugust: 3.21 in precipitation 3.2 AugSeptember: 3.70 in precipitation 3.7 SepOctober: 3.30 in precipitation, 0.6 in snowfall 3.3❄1 OctNovember: 3.07 in precipitation, 0.2 in snowfall 3.1 NovDecember: 3.15 in precipitation, 5.5 in snowfall 3.1❄6 Dec

NOAA NCEI U.S. Climate Normals 1991–2020 — temperature: Raystown Lake 2, PA (9 mi away); precipitation: Saxton 1w, PA (8 mi away). Daylight is calculated from latitude.

Nearby ZIP codes

1 of the 8 nearest ZIP codes are in a different zone — elevation and distance from water change winter lows quickly.

166856b
Todd, PA · 2 mi
166236b
Cassville, PA · 4 mi
166346b
Dudley, PA · 5 mi
166946b
Wood, PA · 5 mi
166746b
Robertsdale, PA · 5 mi
166226b
Calvin, PA · 5 mi
166576b
James Creek, PA · 6 mi
172537a
Saltillo, PA · 6 mi

Pennsylvania planting zones →

Questions about 16621

What planting zone is ZIP code 16621?

ZIP code 16621 (Broad Top, 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 Broad Top, PA?

The median last spring frost (32 °F) near 16621 is April 19; after May 7 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Raystown Lake 2 station.

When is the first frost in Broad Top, PA?

The median first fall frost near 16621 is October 28, giving a median frost-free growing season of 191 days.

When should I plant tomatoes in 16621?

Start tomato seeds indoors around Feb 22 – Mar 8 and set transplants outside around Apr 26 – May 10, one to three weeks after the median last frost.

How much rain and snow does 16621 get?

About 41.1 inches of precipitation a year and 23 inches of snowfall (NOAA 1991–2020 normals, Saxton 1w station).

How hot do summers get in Broad Top, PA?

The average high peaks at 85 °F in July, with about 14 days a year at 90 °F or more.

What kind of soil does 16621 have?

The USDA soil survey maps Meckesville at the center of ZIP 16621: channery silt loam, well drained, pH about 4.6 (strongly acidic).

Did spring come early in Broad Top, PA in 2026?

Spring leaf-out near 16621 came on Mar 29 in 2026, 7 days earlier than the 1991–2020 average (Apr 5), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Broad Top, PA?

Long-day onions: the longest day near 16621 is 15 h 03 min, so summer days reach 15+ hours, enough for long-day varieties (intermediate types work too).

Did the zone for 16621 change?

Yes. The 2012 USDA map put 16621 in zone 6a; the 2023 map puts it in zone 6b. The newer map uses 1991–2020 data and more weather stations.