Climate · Caernarvon

Caernarvon, PA climate

Caernarvon has chilly winters and warm summers, with plenty of rain. A typical July afternoon reaches 85°, a January night drops to 22°, and about 26 inches of snow falls in a normal winter.

NOAA 1991-2020 climate normals Updated once a decade
July high
85°
906th hottest of 3,547 Pennsylvania towns
January low
22°
797th mildest of 3,547 Pennsylvania towns
Rain + melted snow
49 in
416th wettest of 3,547 Pennsylvania towns
Snow a winter
26 in
937th least snowy of 3,541 Pennsylvania towns
A normal year

What a year in Caernarvon feels like

Winter

41° / 24°
Typical high / low · 8 days with an inch or more of snow

Spring

62° / 40°
Typical high / low · Last frost around Apr 16

Summer

83° / 62°
Typical high / low · 12 days reach 90° in a normal year

Fall

65° / 44°
Typical high / low · First frost around Oct 27
Best months to be outsideMayJunAugSepOctHighs of 62–84° and lows of 40° or more
Month by month

Caernarvon weather by month

Average highs, lows, rain and snow for every month, from NOAA’s 1991–2020 normals.

MonthHighLowRain + meltSnowWet days30-yr range
January39°22°3.4" 4.7"10 21° – 38°
February42°24°2.8" 12.4"10 22° – 40°
March50°30°4.2" 3.3"9 34° – 49°
April63°40°3.7" 0.3"10 47° – 56°
May72°50°3.8" 012 57° – 67°
June80°59°4.5" 011 66° – 73°
July85°64°4.8" 010 70° – 78°
August83°62°4.4" 010 68° – 76°
September76°55°5.0" 08 63° – 70°
October65°43°4.4" 0.5"10 49° – 60°
November53°34°3.5" 1.2"8 38° – 48°
December43°27°4.1" 3.9"11 26° – 46°
Year63°42°48.5"26.3"119

“Wet days” have at least 0.01" of rain or melted snow. “Snow on ground” counts days with 1" or more. The 30-year range is the coldest and warmest that month’s average temperature got between 1991 and 2020.

Rain & snow

Rain and snow in Caernarvon

Caernarvon gets 49 inches of rain and melted snow a year. September is the wettest month and February the driest. Rain or snow falls on about 119 days a year.

49 in
Rain + melted snow a year
More rain than 83% of U.S. towns
26 in
Snow in a normal winter
More snow than 52% of U.S. towns
119 days
With rain or snow (0.01"+)

Rain + melted snow by month

Inches of water
5.0"

Snowfall by month

Inches of snow
12"
Frost & the growing season

About 193 frost-free days a year

In half of years the last 32° night comes by April 16 and the first one by October 27. That leaves about 193 frost-free days for gardens, longer than 67% of U.S. towns.

121
nights at or below 32° in a normal year
<1
nights below 0° in a normal year
12
days that reach 90° in a normal year

Freezing nights by month

Average nights at or below 32°

90° days by month

Average days at 90° or more
Heating & cooling

Heating and cooling a home in Caernarvon

Engineers use “degree days” to estimate how hard a furnace or air conditioner works. In Caernarvon, 87% of that work is heating and 13% is cooling, so the furnace matters far more than the air conditioner.

87%heating
5,509 heating degree daysLess heating than 56% of U.S. towns
818 cooling degree daysLess cooling than 52% of U.S. towns

Degree days measure how far each day’s average temperature falls below or rises above 65°, added up over a year. Source: NOAA station normals.

Around Caernarvon

Caernarvon and its neighbors

Caernarvon borders 6 towns with climate data. January nights across them vary by 0.4°. New Morgan has the coldest January nights (21°) and Robeson the hottest July afternoons (86°). Caernarvon’s January low is 22° and its July high 85°.

Exeter: January low 22°, July high 87°Birdsboro: January low 22°, July high 87°Cumru: January low 22°, July high 86°Union: January low 22°, July high 86°Brecknock: January low 22°, July high 85°East Earl: January low 22°, July high 85°Salisbury: January low 22°, July high 85°West Caln: January low 22°, July high 85°West Brandywine: January low 22°, July high 85°East Nantmeal: January low 22°, July high 86°Elverson: January low 22°, July high 85°Wallace: January low 22°, July high 85°Spring: January low 22°, July high 86°New Morgan: January low 21°, July high 85°Robeson: January low 22°, July high 86°Caernarvon: January low 22°, July high 85°Honey Brook: January low 22°, July high 84°West Nantmeal: January low 22°, July high 85°Brecknock: January low 22°, July high 85°Caernarvon: January low 22°, July high 85° CaernarvonNew MorganRobesonCaernarvonHoney BrookWest NantmealBrecknock
ColderMilder21° to 22°
New Morgan21.4° −0.2°
Honey Brook21.5° −0.1°
Brecknock21.5° −0.1°
Caernarvon21.6°
West Nantmeal21.6° same
Robeson21.7° +0.1°
Caernarvon21.8° +0.2°

Temperatures and rain come from NOAA’s 5 km grid, so each town gets its own value.

Compared with other towns

How Caernarvon compares

Summer heat85° July high
Hotter than 52% of U.S. towns906th hottest of 3,547 Pennsylvania towns
Winter cold22° January low
Milder than 61% of U.S. towns797th mildest of 3,547 Pennsylvania towns
Precipitation49" a year
Wetter than 83% of U.S. towns416th wettest of 3,547 Pennsylvania towns
Snow26" a winter
Snowier than 52% of U.S. towns937th least snowy of 3,541 Pennsylvania towns
Growing season193 frost-free days
Longer than 67% of U.S. towns411th longest of 3,547 Pennsylvania towns

Compared with every U.S. town and city on TownTapestry, each counted once.

Then and now

Warmer than it used to be

+1.8°1991–2020 average vs. the 20th century (1901–2000)

The last 30 years in Caernarvon averaged 1.8° warmer than the 1900s. The biggest change is in December (+3.4°). The shift is larger than in 88% of U.S. towns.

❄️ Winter+2.8° now 32°, was 30°
🌷 Spring+1.6° now 51°, was 49°
☀️ Summer+1.5° now 72°, was 71°
🍂 Fall+1.4° now 54°, was 53°

Change by month1991–2020 average minus 1901–2000 average, at Caernarvon’s spot on NOAA’s grid

Year to year

How much a month can swing

A normal is an average, and real years wander around it. December swings the most: between 1991 and 2020 its average temperature ranged from 26° to 46°. June is the most reliable, staying within 7°.

Coldest to warmest month in 30 yearsNormal
Questions

Common questions about Caernarvon’s climate

What is the coldest month in Caernarvon?

January, with a typical high of 39° and a low of 22°.

What is the hottest month in Caernarvon?

July, with a typical high of 85° and a low of 64°. About 12 days a year reach 90°.

How much snow does Caernarvon get?

About 26 inches in a normal winter, most of it in February.

When is the first frost in Caernarvon?

In half of years the first 32° night comes by October 27, and the last spring frost by April 16.

What is the rainiest month in Caernarvon?

September, with 5.0 inches of rain and melted snow. The year totals 49 inches.

Temperatures and rainfall come from NOAA’s gridded climate normals for Caernarvon itself (about a 3-mile square). Snow, frost dates and day counts come from NOAA’s weather station at Morgantown, PA (1 mi, snow) and Hopewell Morgantown, PA (1 mi, frost, heat and degree days). Normals are 30-year averages, not a forecast. Source: NOAA NCEI U.S. Climate Normals, 1991–2020 and 1901–2000.

The coffee’s on

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Boundary source: https://tigerweb.geo.census.gov/arcgis/rest/services/TIGERweb/Places_CouSub_ConCity_SubMCD/MapServer/15 · 2025-01-01