Weather StoryAlmanac, microseasons, and the day's weather story.

Norristown, Pennsylvania Weather

Cicadas claim the afternoon. Day 14 of summer. Read this microseason across nine climate regions →

Norristown weather forecast — hour by hour, 7-day outlook, NOAA radar

Norristown, PA
Saturday, July 4 at 7:56 AM
82
°
Clear
Feels like
87°
Humidity
63%
Wind
5 mph
Sunrise
1:37 AM
Sunset
4:34 PM
Norristown, PA
Hour by hour · 24h
24-Hour ForecastNorristown, PA: 24-hour forecast. Temperatures range from 75 to 102 degrees Fahrenheit with a 44% chance of precipitation at 10 PM.
L 75°H 102°
Norristown, PA
7-day forecast
  1. Today
    Jul 4
    Drizzle
    44%
    0.05″
    102°73°—
  2. Sunday
    Jul 5
    Heavy Rain
    92%
    1.8″
    97°72°-5°
  3. Monday
    Jul 6
    T-storm w/ Hail
    92%
    0.31″
    75°65°-22°
  4. Tuesday
    Jul 7
    Light Drizzle
    72%
    0.01″
    70°62°-5°
  5. Wednesday
    Jul 8
    Partly Cloudy
    15%
    —
    85°58°+15°
  6. Thursday
    Jul 9
    Mostly Clear
    28%
    —
    91°67°+6°
  7. Friday
    Jul 10
    Light Drizzle
    33%
    —
    92°71°+1°
Norristown, PA
Next 24 hours · Mild now
HOT 90°70°90°110°6a12p6p12anow 77°high 102°low 75°PRECIP %
Norristown, PA
Anemometer · 24h winds · from true
NESW
From · True
W
273° · veering 27°
Direction
W
273°
Sustained
5
mph
Gust
11
mph
Peak 24h
48
avg 6
Beaufort · 2 · LIGHT BRZ
0
CALM
<1
1
LIGHT AIR
1–3
2
LIGHT BRZ
4–7
3
GENTLE BRZ
8–12
4
MOD BRZ
13–18
5
FRESH BRZ
19–24
6
STRONG BRZ
25–31
7
NEAR GALE
32–38
24h · sust vs gust · mph
avg 6 · pk 48 @ 8:00p
01020304050MPHB1B2B3B4B5B6B7B8B9-21h-18h-15h-12h-9h-6h-3h-24hNOWpk 511SUSTGUST
−24h−18h−12h−6hnow
Light breeze veering 27° from the w.
Norristown, PA
Barometer · 24h pressure · mb
STORMRAINCHANGEFAIRDRY9901000101010201030
Pressure · mb
1008.9
-0.3 mb in 3h · steady · 29.79 inHg
Now
1008.9
mb
3h
-0.3
mb
12h
+1.0
mb
24h
-2.8
mb
Regime · RAIN
STORM
RAIN
CHANGE
FAIR
DRY
24h · Pressure · mb
range 1008–1012
1000STORM|RAIN10051010RAIN|CHG1015CHG|FAIR10201025FAIR|DRY1030-21h-18h-15h-12h-9h-6h-3h-24hNOW1012.01008.01009.0
−24h−18h−12h−6hnow
Damp, unsettled regime — wet weather lingers nearby.
Norristown, PA
Air quality
63
AQI
Moderate
↑+7 in 6h▲Peak ~71 @ 6 PM

AQI 63 (Moderate), driven by PM2.5. AQI up 7 over the last 6 hours (gradual rise). PM2.5 at 22.3 µg/m³ (AQI 76) with a 0.91 fine-to-coarse ratio and 5 mph wind — combustion smoke trapped in calm air, not road dust.

OK No precautions needed for the general population; unusually sensitive individuals may consider limiting prolonged outdoor exertion during the projected peak around 6 PM.

PM 2.5DRIVERModerate
22.3μg/m³
PM 10Good
25μg/m³
NO₂Good
15μg/m³
OzoneModerate
74μg/m³
UV IndexLow
0.5

What's driving it

Ozone × UV × Sky

Ozone at AQI 35 now. With UV 1.7 peaking around 1 PM under clear skies, surface ozone likely climbs to AQI 8 around 1 PM.

Present
AQI 35
UV peak
1.7 at 1 PM
Sky at peak
clear
Projected peak
AQI 8

PM × Wind × Precip

PM2.5 at 22.3 µg/m³ (AQI 76) with a 0.91 fine-to-coarse ratio and 5 mph wind — combustion smoke trapped in calm air, not road dust.

PM2.5/PM10
0.91
Wind
light
Recent rain
0h in last 6h
Pattern
stagnant smoke

Trends

Seven days of AQI and PM2.5.

Hourly air-quality data from the Copernicus Atmosphere Monitoring Service, charted across the past and next several days. Dashed lines mark the AQI breakpoints at 50 (Good → Moderate) and 100 (Moderate → Unhealthy for Sensitive Groups).

7-DAY AQI TREND50100SATSUNMONTUEWEDTHUFRISAT7-DAY PM2.5 TREND · μg/m³450
Norristown, PA
Sky cover · visibility · 24h
Cloud cover
0%
CLEAR
100%0%−24h−18h−12h−6hnow
Visibility
56.9mi
UNLIMITED
97 mi0 mi−24h−18h−12h−6hnow
Earth · GOES-19 ABI
Full Disk · Visible · GeoColor
GOES-19 full disk Visible · GeoColor
True-color daytime, blue/IR sandwich at night
11:56 UTC · Norristown, PA · NOAA NESDIS / STAR · up to 10848 px
Continental US · GOES-19 ABI
CONUS Sector · Visible · GeoColor
GOES-19 CONUS Visible · GeoColor
Daytime true-color, blue-light/IR sandwich at night
11:56 UTC · Norristown, PA · NOAA NESDIS / STAR · 5-min cadence · up to 10000 px
Norristown, PA
Satellite · infrared · animated
Norristown, PA
Loading IR frames…
IR · cloud-top temp© RainViewer · Carto
Norristown, PA
Almanac · Saturday, July 4
If the first of July be rainy weather, 'twill rain more or less for four weeks together.
Civil dawn
5:05 AM
Sunrise
1:37 AM
Daylight
14h 57m
Sunset
4:34 PM
Civil dusk
9:07 PM
Planting note
Harvest early potatoes. Begin drying onions on the surface.
Norristown, PA
The moon
Waning Gibbous
82% illuminated
Moonrise
10:55 PM
Moonset
10:04 AM
In sign
♓︎ Pisces
Norristown, PA
Microseason
Jul 1–5

Cicadas claim the afternoon

plant
Jan 151% of the yearDec 31

Read this microseason across nine climate regions →

Norristown at a glance

  • Today vs. normal: 10°F above the seasonal normal for this latitude
  • Last frost: April 17 (climatological average for this latitude)
  • Microseason: Jul 1–5
  • Planting window: Harvest early potatoes. Begin drying onions on the surface.

ZIP codes: 19401, 19403

16-Day Forecast — Norristown

  1. Sat102°73°44%
  2. Sun97°72°92%
  3. Mon75°65°92%
  4. Tue70°62°72%
  5. Wed85°58°15%
  6. Thu91°67°28%
  7. Fri92°71°33%
  8. Sat82°72°32%
  9. Sun74°67°29%
  10. Mon72°67°15%
  11. Tue82°65°16%
  12. Wed90°67°24%
  13. Thu93°74°23%
  14. Fri95°76°34%
  15. Sat77°72°39%
  16. Sun88°70°35%

Forecast data from Open-Meteo (CC BY 4.0).

Right now in the garden

Peak growing season

As of July 4, the growing season is at its peak — frost is months away. Continue succession-planting beans and summer squash. Start fall brassicas (broccoli, cabbage, kale) from seed indoors for transplanting in late summer.

SPC Convective Outlook

Storm Prediction Center — Norristown

SPC has placed Norristown in the Slight Risk category for severe thunderstorms today.

  • TODAYSLGTSlight Risk
  • TOMORROWSLGTSlight Risk
  • DAY 3TSTMGeneral Thunderstorms

Scattered severe storms possible. A few tornadoes, hail, and damaging wind gusts possible.

Source: NOAA / NWS Storm Prediction Center categorical convective outlook. Outlooks are re-issued multiple times per day; this page reflects the most recent SPC polygons covering the city’s coordinates.

January 1–5: The year turns in silence.January 6–10: Ice thickens on still water.January 11–15: Shortest shadows lengthen.January 16–20: Pheasants begin to call.January 21–25: Springs begin to thaw.January 26–31: Chickadees announce dawn.February 1–5: East wind softens the frost.February 6–10: Sap begins to rise.February 11–15: First snowdrops appear.February 16–20: Red-winged blackbirds return.February 21–25: Rain begins to replace snow.February 26–28: Skunk cabbage pushes through ice.March 1–5: Ice withdraws from the reservoir.March 6–10: Crocuses open to weak sun.March 11–15: Peepers call from the marsh.March 16–20: Woodcocks spiral at dusk.March 21–25: Equinox — light overtakes dark.March 26–31: Forsythia opens along the fences.April 1–5: Cherry blossoms drift like snow.April 6–10: Warblers appear in the understory.April 11–15: Magnolias bloom and fall in a day.April 16–20: Dogwoods float above the forest.April 21–25: Lilacs perfume the evening.April 26–30: Last frost releases the garden.May 1–5: Warblers flood the Ramble.May 6–10: Tulip poplars light their candles.May 11–15: Shad run up the rivers.May 16–20: Roses open along the stoops.May 21–25: Firefly scouts appear at dusk.May 26–31: Strawberries ripen in the sun.June 1–5: Fireflies rise from the lawn.June 6–10: Elderflowers open in hedgerows.June 11–15: Solstice approaches — longest light.June 16–20: Honeysuckle sweetens the night.June 21–25: Solstice — the sun stands still.June 26–30: Lightning bugs drift through oaks.July 1–5: Cicadas claim the afternoon.July 6–10: Queen Anne's lace lines the roads.July 11–15: Thunder builds each afternoon.July 16–20: Corn reaches for the tassels.July 21–25: Dog days settle in the haze.July 26–31: Katydids begin their chorus.August 1–5: Night falls a minute earlier.August 6–10: Sunflowers face the morning.August 11–15: Goldenrod begins to bloom.August 16–20: Crickets pulse through warm nights.August 21–25: First cool morning surprises.August 26–31: Monarchs stage for flight.September 1–5: School buses reappear.September 6–10: Asters purple the roadsides.September 11–15: Hawk migration over the Hudson.September 16–20: Equinox — dark overtakes light.September 21–25: Apples hang heavy on the branch.September 26–30: Geese begin to chevron south.October 1–5: Witch hazel blooms as others fade.October 6–10: Maples begin to blaze.October 11–15: Frost paints the garden black.October 16–20: Oaks turn bronze and russet.October 21–25: Leaves rattle down the gutters.October 26–31: Clocks fall back — dusk at five.November 1–5: Ginkgos drop overnight.November 6–10: Last leaves cling stubbornly.November 11–15: Juncos arrive from the north.November 16–20: Bare branches reveal the sky.November 21–25: First flurries dust the rooftops.November 26–30: Woodsmoke curls through the block.December 1–5: Darkness settles before dinner.December 6–10: Holly and winterberry persist.December 11–15: Shortest day approaches.December 16–20: Ice begins to form at the edges.December 21–25: Solstice — the sun begins return.December 26–31: The year turns in silence.🌱February 14 — First skunk-cabbage spathes thaw their way up☀️March 20 — Spring equinox — day and night balance🌸April 5 — Cherry blossoms peak in the parks🐦May 10 — Warbler migration peaks along the coast✨May 25 — First fireflies scout the meadows at dusk🌞June 21 — Summer solstice — longest day🦗July 25 — Peak cicada chorus in the afternoons🌊August 18 — Warmest sea-surface temperatures of the year🍂September 22 — Autumn equinox — the slow turn❄️October 25 — First widespread frost in the suburbs🍁November 10 — Peak leaf color across the Hudson Valley🌙December 21 — Winter solstice — longest night

Microseason · July 1–5

Cicadas claim the afternoon

Annual cicada buzz begins, peaking in the heat of the day.

Day 185 of 365 · Wedge 37 of 72

The solar year drawn as a wheel of 72 five-day windows. Each wedge is one microseason; the four colored arcs mark winter, spring, summer, and autumn; the small icons sit at notable phenological events. The crimson pointer creeps clockwise as the year turns.

Planting calendar

MonthPlantHarvest
January——
February——
March——
Aprillettuce, peas, spinach, radishes—
Maylettuce, peas, spinach, radishes, tomatoes, peppers, beans, squashlettuce, peas, radishes
Junetomatoes, peppers, beans, squashlettuce, peas, radishes
Julytomatoes, peppers, beans, squashtomatoes, beans, summer squash
August—tomatoes, beans, summer squash
Septemberfall brassicas, garlic (overwinter), carrotstomatoes, beans, summer squash
Octoberfall brassicas, garlic (overwinter), carrotswinter squash, tomatoes (last)
November——
December——

A year in weather

Norristown peaks at about 77°F in July and bottoms near 31°F in January; December brings the heaviest rain (4.2 inches) and February the least (2.9 inches).

MonthMean tempPrecipRainy days
January31°3.4″13
February33°2.9″12
March42°3.7″15
April53°3.9″17
May61°3.7″17
June71°3.7″17
July77°3.3″16
August75°4.0″17
September69°3.7″13
October58°3.0″11
November45°3.6″13
December36°4.2″13

Regional context

By the nearest station's NOAA NCEI 1991-2020 normals, Norristown sees 31°F Januarys and 77°F Julys, a 46°F range, plus around 43.1 inches of precipitation across 173 days.

No season owns Norristown's rain: December reaches 4.2 inches across 13.0 days and February keeps 2.9 inches on 12.4, an even spread through Norristown's year. That lines Norristown up with places like Bridgeport, PA, Swedesburg, PA and Swedeland, PA, fed by overlapping storm tracks.

Norristown's growing window opens around mid-April, once Norristown's overnight lows stop freezing — sow peas, lettuce, spinach, and radishes. In Norristown, warm-season transplants — tomatoes, peppers, basil — wait two weeks past Norristown's frost date. Norristown's window closes around mid-November as overnight lows return below freezing. In Norristown, low spots run 4-7°F colder than nearby slopes, nudging Norristown's frost dates a week.

Similar climates: Bridgeport, PA, Swedesburg, PA, Swedeland, PA, King of Prussia, PA, Plymouth Meeting, PA.

Frequently asked

When does it freeze in Norristown?
Norristown's last spring frost lands near mid-April, and in Norristown the first fall frost follows around mid-November.
What is the rainy season in Norristown?
December is the wettest month in Norristown, about 4.2 inches on average; the year totals roughly 43 inches.
What is the warmest month in Norristown?
The warmest stretch in Norristown comes in July, around 77°F on average.
What is the coldest month in Norristown?
On average January is the chilliest month in Norristown, about 31°F.
When can I start a vegetable garden in Norristown?
Time tomatoes in Norristown for two weeks after mid-April; peas and greens start at Norristown's frost line.
How many rainy days does Norristown get?
Norristown averages about 173 days with measurable rain or snow each year.
What hardiness zone is Norristown?
Norristown's USDA zone comes from its January mean (31°F); enter the ZIP on the USDA lookup for the number.
What is the 10-day forecast for Norristown?
Norristown's extended outlook — daily high and low temperatures and precipitation chances for each upcoming day — is in the daily forecast above.
Will it rain this week in Norristown?
See this week's day-by-day rain chances for Norristown in the daily forecast above, and the next 24 hours in the hourly chart.
What is the weather like right now in Norristown?
Current conditions for Norristown and the next 24 hours — temperature, precipitation chance, and wind by the hour — are in the hourly forecast chart above.
How often is the Norristown forecast updated?
The Norristown forecast on this page is built from Open-Meteo weather-model data and refreshes regularly through the day.
When are sunrise and sunset in Norristown?
Today's sunrise and sunset times for Norristown are in the Almanac section above, along with civil dawn, civil dusk, and day length. Day length is longest near the summer solstice and shortest near the winter solstice.
How accurate is the weather forecast for Norristown?
The next few days in Norristown's forecast are the most reliable; accuracy declines beyond about a week as weather-model uncertainty grows.

Climate

Norristown, Pennsylvania has a warm-summer humid continental climate: January averages roughly 31°F, July about 77°F, 46°F between them.

In a typical year Norristown records about 43 inches of precipitation on around 173 days.

At 40.1°N, Norristown's 46°F summer-to-winter swing sets when Norristown's gardens wake and when frost returns.

All cities in Pennsylvania →

Philadelphia, PA weather →

ZIP codes in Norristown

  • 19401
  • 19404
  • 19409
  • 19415

Climate normals from the Open-Meteo Climate API. Köppen approximation from NOAA NCEI U.S. Climate Regions. See methodology for data sources, editorial rules, and corrections. Maintainer: Brian Tighe.