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

Planting zone for 19403 — Norristown, PA

ZIP code 19403 (Norristown, Montgomery County) is in USDA zone 7a: the coldest winter night averages 0 to 5 °F. The median last spring frost is April 8 and the first fall frost October 31.

Where ZIP 19403 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.

Zone7a0 to 5 °F
Coldest night−17.8 to −15 °C
Last frostApr 8
First frostOct 31
2012 zone7a

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 7a means →

Frost forecast — next 7 nights

live from the National Weather Service

Loading the forecast for Norristown, 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 Norristown, PA

JanFebMarAprMayJunJulAugSepOctNovDec
Blue: frost possible · fading green: frost risk falling or rising (90% → 10%) · green: frost-free
Last spring frostApril 8median — 50% chance of a later frost
Safe for tender plantsApril 23only 10% chance of frost after
First fall frostOctober 31median — 10% chance by Oct 14
Growing season203 daysfrost-free, median

A hard freeze (28 °F) usually ends around March 31 and returns around November 10.

From the NOAA station Norristown, PA — 4 miles away, elevation 62 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 19403

JanFebMarAprMayJunJulAugSepOctNovDec
PeasSow outdoors · Feb 25 – Mar 11
SpinachSow outdoors · Feb 25 – Mar 18
Broccoli, cabbageStart indoors · Jan 28 – Feb 11
Broccoli, cabbageTransplant · Mar 18 – Apr 1
Onion setsPlant outdoors · Mar 11 – Mar 25
PotatoesPlant outdoors · Mar 18 – Apr 1
LettuceSow outdoors · Mar 11 – Mar 25
Carrots, beetsSow outdoors · Mar 18 – Apr 1
TomatoesStart indoors · Feb 11 – Feb 25
TomatoesTransplant · Apr 15 – Apr 29
Peppers, eggplantStart indoors · Jan 28 – Feb 11
Peppers, eggplantTransplant · Apr 22 – May 6
BeansSow outdoors · Apr 15 – Apr 29
Sweet cornSow outdoors · Apr 15 – Apr 29
Cucumbers, squashSow outdoors · Apr 15 – Apr 29
Fall lettuce, spinachSow outdoors · Sep 5 – Sep 19
GarlicPlant cloves · Oct 17 – Nov 21
Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (Apr 8) and first fall frost (Oct 31) 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 19403 came on Mar 24 — 3 days earlier than the 1991–2020 average (Mar 27).

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 7a in Pennsylvania

620 plants native to the lower 48 states, recorded in Pennsylvania, and rated by the USDA to survive 0 °F or colder — the bottom of zone 7a. Each links to its USDA PLANTS profile.

Trees 78

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 123

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 212

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 181

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 11

American bittersweet15 ft · blooms spring · low shade tolerance · to −38 °FAmerican wisteria50 ft · blooms spring · low shade tolerance · to −3 °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 °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 Norristown, PA.

Soil in Norristown, PA

The soil mapped at the center of ZIP 19403 is Penn — channery silt loam, well drained. Much of the area is built over (urban land); this is the natural soil underneath.

TextureChannery silt loama good balance for most vegetables
pH5.4strongly acidic; most vegetables like 6.0–7.0
DrainageWell drainednatural drainage class
Organic matter2%moderate
Hydrologic groupBwater soaks in moderately
Farmland classNot prime farmlandUSDA classification

Map unit: Urban land-Penn complex, 8 to 25 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 19403; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Norristown, PA

Summer high89 °Faverage high, July
Winter low23 °Faverage low, January
Hot days39days a year at 90 °F or more
Freezing nights107nights a year at 32 °F or less
Growing degree days3,815base 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)
Precipitation50.6 inper year, rain and melted snow
Snowfall25 inper year

Average high and low, by month

10°20°30°40°50°60°70°80°90°100°32 °FJanuary: average high 42 °F, low 23 °F 42°23° JanFebruary: average high 44 °F, low 25 °F 44°25° FebMarch: average high 52 °F, low 32 °F 52°32° MarApril: average high 65 °F, low 42 °F 65°42° AprMay: average high 75 °F, low 52 °F 75°52° MayJune: average high 84 °F, low 62 °F 84°62° JunJuly: average high 89 °F, low 67 °F 89°67° JulAugust: average high 87 °F, low 65 °F 87°65° AugSeptember: average high 80 °F, low 58 °F 80°58° SepOctober: average high 68 °F, low 45 °F 68°45° OctNovember: average high 57 °F, low 35 °F 57°35° NovDecember: average high 46 °F, low 28 °F 46°28° Dec

Precipitation by month inches · ❄ = snowfall

0″1″2″3″4″5″January: 3.66 in precipitation, 6.8 in snowfall 3.7❄7 JanFebruary: 2.98 in precipitation, 10.9 in snowfall 3.0❄11 FebMarch: 4.41 in precipitation, 3 in snowfall 4.4❄3 MarApril: 3.90 in precipitation, 0.2 in snowfall 3.9 AprMay: 4.25 in precipitation 4.3 MayJune: 4.20 in precipitation 4.2 JunJuly: 4.70 in precipitation 4.7 JulAugust: 4.98 in precipitation 5.0 AugSeptember: 4.91 in precipitation 4.9 SepOctober: 4.32 in precipitation, 0.1 in snowfall 4.3 OctNovember: 3.61 in precipitation, 0.1 in snowfall 3.6 NovDecember: 4.73 in precipitation, 4.2 in snowfall 4.7❄4 Dec

NOAA NCEI U.S. Climate Normals 1991–2020 — temperature: Norristown, PA (4 mi away); precipitation: Norristown, 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.

194097a
Fairview Village, PA · <1 mi
194157a
Eagleville, PA · 2 mi
194087a
Eagleville, PA · 2 mi
194017a
Norristown, PA · 3 mi
194307a
Creamery, PA · 3 mi
194907a
Worcester, PA · 4 mi
194067a
King Of Prussia, PA · 4 mi
194057b
Bridgeport, PA · 4 mi

All 3 ZIP codes in Norristown → · Pennsylvania planting zones →

Questions about 19403

What planting zone is ZIP code 19403?

ZIP code 19403 (Norristown, PA) is in USDA hardiness zone 7a on the 2023 map: the coldest night of an average winter reaches 0 to 5 °F (−17.8 to −15 °C).

When is the last frost in Norristown, PA?

The median last spring frost (32 °F) near 19403 is April 8; after April 23 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Norristown station.

When is the first frost in Norristown, PA?

The median first fall frost near 19403 is October 31, giving a median frost-free growing season of 203 days.

When should I plant tomatoes in 19403?

Start tomato seeds indoors around Feb 11 – Feb 25 and set transplants outside around Apr 15 – Apr 29, one to three weeks after the median last frost.

How much rain and snow does 19403 get?

About 50.6 inches of precipitation a year and 25 inches of snowfall (NOAA 1991–2020 normals, Norristown station).

How hot do summers get in Norristown, PA?

The average high peaks at 89 °F in July, with about 39 days a year at 90 °F or more.

What kind of soil does 19403 have?

The USDA soil survey maps Penn at the center of ZIP 19403: channery silt loam, well drained, pH about 5.4 (strongly acidic).

Did spring come early in Norristown, PA in 2026?

Spring leaf-out near 19403 came on Mar 24 in 2026, 3 days earlier than the 1991–2020 average (Mar 27), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Norristown, PA?

Long-day onions: the longest day near 19403 is 15 h 02 min, so summer days reach 15+ hours, enough for long-day varieties (intermediate types work too).