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

Planting zone for 15520 — Acosta, PA

ZIP code 15520 (Acosta, Somerset County) is in USDA zone 6a: the coldest winter night averages −10 to −5 °F. The median last spring frost is May 6 and the first fall frost October 12.

Where ZIP 15520 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 6

First frostOct 12

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 Acosta, 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 Acosta, PA

JanFebMarAprMayJunJulAugSepOctNovDec

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

Last spring frostMay 6median — 50% chance of a later frost

Safe for tender plantsMay 23only 10% chance of frost after

First fall frostOctober 12median — 10% chance by Oct 1

Growing season159 daysfrost-free, median

A hard freeze (28 °F) usually ends around April 27 and returns around October 24.

From the NOAA station Laurel Summit, PA — 6 miles away, elevation 2,730 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 15520

JanFebMarAprMayJunJulAugSepOctNovDec

PeasSow outdoors · Mar 25 – Apr 8

SpinachSow outdoors · Mar 25 – Apr 15

Broccoli, cabbageStart indoors · Feb 25 – Mar 11

Broccoli, cabbageTransplant · Apr 15 – Apr 29

Onion setsPlant outdoors · Apr 8 – Apr 22

PotatoesPlant outdoors · Apr 15 – Apr 29

LettuceSow outdoors · Apr 8 – Apr 22

Carrots, beetsSow outdoors · Apr 15 – Apr 29

TomatoesStart indoors · Mar 11 – Mar 25

TomatoesTransplant · May 13 – May 27

Peppers, eggplantStart indoors · Feb 25 – Mar 11

Peppers, eggplantTransplant · May 20 – Jun 3

BeansSow outdoors · May 13 – May 27

Sweet cornSow outdoors · May 13 – May 27

Cucumbers, squashSow outdoors · May 13 – May 27

Fall lettuce, spinachSow outdoors · Aug 17 – Aug 31

GarlicPlant cloves · Sep 28 – Nov 2

Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (May 6) and first fall frost (Oct 12) 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 15520 came on Mar 15 — 22 days earlier than the 1991–2020 average (Apr 6).

average
Apr 62026
Mar 15

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 Acosta, PA

The soil mapped at the center of ZIP 15520 is Bethesda — very channery silt loam, well drained.

TextureVery channery silt loama good balance for most vegetables

pH4.6strongly acidic; most vegetables like 6.0–7.0

DrainageWell drainednatural drainage class

Organic matter0.25%low — add compost

Hydrologic groupCwater soaks in slowly

Farmland classNot prime farmlandUSDA classification

Map unit: Udorthents, mine spoil, 25 to 70 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 15520; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Acosta, PA

Summer high75 °Faverage high, July

Winter low14 °Faverage low, January

Hot days0days a year at 90 °F or more

Freezing nights146nights a year at 32 °F or less

Growing degree days2,036base 50 °F — the season’s usable heat

Longest day15 h 02 mindaylight on June 21

Shortest day9 h 19 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

Snowfall65 inper year; 61 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: Laurel Summit, PA (6 mi away); precipitation: Boswell, PA (4 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.

155556a

Quecreek, PA · 1 mi

155615b

Sipesville, PA · 2 mi

Jennerstown, PA · 4 mi

Pennsylvania planting zones →

Questions about 15520

What planting zone is ZIP code 15520?

ZIP code 15520 (Acosta, 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 Acosta, PA?

The median last spring frost (32 °F) near 15520 is May 6; after May 23 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Laurel Summit station.

When is the first frost in Acosta, PA?

The median first fall frost near 15520 is October 12, giving a median frost-free growing season of 159 days.

When should I plant tomatoes in 15520?

Start tomato seeds indoors around Mar 11 – Mar 25 and set transplants outside around May 13 – May 27, one to three weeks after the median last frost.

How much rain and snow does 15520 get?

About 45 inches of precipitation a year and 65 inches of snowfall (NOAA 1991–2020 normals, Boswell station).

How hot do summers get in Acosta, PA?

The average high peaks at 75 °F in July, with about 0 days a year at 90 °F or more.

What kind of soil does 15520 have?

The USDA soil survey maps Bethesda at the center of ZIP 15520: very channery silt loam, well drained, pH about 4.6 (strongly acidic).

Did spring come early in Acosta, PA in 2026?

Spring leaf-out near 15520 came on Mar 15 in 2026, 22 days earlier than the 1991–2020 average (Apr 6), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Acosta, PA?

Long-day onions: the longest day near 15520 is 15 h 02 min, so summer days reach 15+ hours, enough for long-day varieties (intermediate types work too).

Did the zone for 15520 change?

Yes. The 2012 USDA map put 15520 in zone 5b; the 2023 map puts it in zone 6a. The newer map uses 1991–2020 data and more weather stations.