FORECAST CITY
Sign in
Shaded-relief map of Caln, Pennsylvania: rivers, roads, the city limits and where the water drains.
PENNSYLVANIA · CHESTER COUNTY

Caln

15,203 people, 340 ft above sea level in Chester County.

340 ftElevation, city center
15,203People, 2024 estimate
9 sq miLand area
Sunny 47°
Sunny now Dew point 29° · WNW 13 mph · high 49°
City of Caln River Interstate 2 miles
Explore the plate Order a print

The Caln plate. Relief from Copernicus GLO-30; rivers and lakes from USGS NHD; watersheds from the USGS Watershed Boundary Dataset; roads and city limits from Census TIGER 2024.

MILE1
TODAY

Today in Caln

NWS forecast and National Blend of Models · updated 4:00 PM EST
RIGHT NOW Philadelphia International Airport (KPHL) · 3:54 PM
Sunny
47° Sunny Feels like 41° · high of 49° near 4 PM
WindWNW 13 mphno gusts
Humidity49%rising to 82% by morning
Pressure29.87 in →steady
Visibility10 mihaze-free
CloudsClear
UV index—no forecast
Dew point 29° · Dryabout the same for three days
DryComfortableStickyMuggyOppressive
NEXT RAIN
Clear
Not this weeknone in the forecast for a week
LIKELY AMOUNT—nothing expected
LAST RAINNov. 120.57 in · 2 dry days
ALERTS & OUTLOOKS
No watches or warnings for Chester County
NWS Mount Holly and the Storm Prediction Center · checked 4:47 PM
SUN & MOON
↑ 6:47 AM4:48 PM ↓
10 h 1 m of daylight, 2 minutes less than yesterday
Waxing crescent, 26% lit. Next full moon: Nov. 24.
AIR & POLLEN
21
GOODAir quality index · ozone
No pollen source yet.

The next three days, hour by hour

Sky: clear, cloudy, night Rain likely National Blend of Models
SATURDAY, NOV. 14
SUNDAY, NOV. 15
MONDAY, NOV. 16
TUESDAY, NOV. 17
4p
7p
10p
1a
4a
7a
10a
1p
4p
7p
10p
1a
4a
7a
10a
1p
4p
7p
10p
1a
4a
7a
10a
1p
mostly cloudy night
partly cloudy night
partly cloudy night
mostly clear night
mostly clear night
mostly sunny
mostly sunny
partly cloudy day
partly cloudy night
partly cloudy night
mostly clear night
mostly clear night
mostly clear night
mostly sunny
mostly sunny
mostly sunny
mostly clear night
clear night
clear night
clear night
mostly clear night
mostly sunny
mostly sunny
clear day
TEMPERATURE °F
49°
39°
54°
37°
56°
36°
CHANCE OF RAIN
50%
WIND, MPH
12
10
10
10
12
12
14
14
10
9
9
8
9
10
12
11
9
7
6
6
6
7
7
8
HOW IT FEELS · DEW POINT
Dry: dew points 28 to 36°

The next seven days, and how sure we are

Forecast, with the range 8 in 10 ensemble members agree on Normal, about 56° / 39°
SAT Nov. 14 Mostly cloudy Mostly cloudy
49° 39°
0% rain — WNW 12 A
SUN Nov. 15 Mostly sunny Mostly sunny
54° 36°
0% rain — NNW 13 A
MON Nov. 16 Mostly sunny Mostly sunny
56° 36°
0% rain — NNW 11 A
TUE Nov. 17 Sunny Sunny
59° 38°
0% rain — WNW 7 A
WED Nov. 18 Sunny Sunny
62° 39°
0% rain — W 7 A
THU Nov. 19 Mostly sunny Mostly sunny
64° 41°
0% rain — SW 6 A
FRI Nov. 20 Mostly sunny Mostly sunny
64° 44°
0% rain — NW 6 B
How sure are we? AModels agree: highs within 4° BSome spread: within 8° CWide spread: check back
Range from the National Blend of Models percentiles · graded on Forecast Scores
AIR MAIL

Where today’s air came from

The air arriving over Caln about 5,000 feet above the ground was over British Columbia three days ago, and over the Great Lakes a day ago, about 2,630 miles back along its path. It came down from about 14,000 feet up, warming and drying as it sank. Near the ground the air came from the Canadian Prairies; at 10,000 feet, from the Gulf of Alaska. It feels dry all the same. Traced back 72 hours through NOAA’s hourly RAP analyses and the GFS beyond them, nine paths at each of three heights.

THIS WEEK, NINE YEARS AGO Nov. 11, 2017

The coldest this week has been

16° on Nov. 11, 2017, the coldest reading for this week of the year since 1992. Next is 19° in 1996.

19°
16°
19962017
Source: NOAA RCC-ACIS, the New Holland 2 SE record since 1992.
MILE2
THE GROUND

What Caln stands on

Caln’s center stands about 340 ft above sea level. Within three miles the land runs from 270 ft to 640 ft, a difference of 370 ft: rolling country. The highest named summit within 15 miles is Welsh Mountain, about 1,080 ft, 12 miles northwest.

The section below crosses 9 rock units mapped at the surface.

Caernarvon to Pennsbury, cut in half

A section northwest to southeast, 24 miles through the town center
250 ft500 ft750 ft1,000 ft CALN340 ftWelsh Mountain1,080 ftHoney Brook690 ftWest Bradford360 ftWest Branch Brandywine Creekabout 200 ftPocopson350 ft ← NW · CaernarvonPennsbury · SE →

Heights every 0.1 mile from the Copernicus GLO-90 surface model; vertical exaggeration about 23×. The colored band under the surface is the rock the state geologic map shows at the surface, not a picture of what lies beneath.

Rock at the surface along the line

Felsic and intermediate gneiss

Muscovite-gneiss. Age: Precambrian. About 8 mi of the line.

"Glenarm Wissahickon" formation

Mica-schist. Age: Paleozoic, 252 to 542 million years old. About 5 mi of the line.

Octoraro Formation

Schist, phyllite. Age: Paleozoic, 252 to 542 million years old. About 3 mi of the line.

Felsic and intermediate gneiss

Gneiss. Age: Precambrian. About 2 mi of the line.

Banded mafic gneiss

Gneiss. Age: Precambrian. About 2 mi of the line.

Chickies Formation

Quartzite, schist. Age: Cambrian, 487 to 542 million years old. About 2 mi of the line.

From the USGS State Geologic Map Compilation (Horton and others, 2017), the states’ geologic maps joined at a common scale. 3 smaller units along the line are not listed.

Heights from Copernicus GLO-90 (a surface model: it includes buildings and tree canopy); summits from USGS GNIS; rivers from USGS NHDPlus HR; rock from the USGS State Geologic Map Compilation.

MILE3
THE WATER

Where Caln’s rain goes

A raindrop that lands in Caln reaches Delaware Bay and the Atlantic Ocean by way of Beaver Creek, East Branch Brandywine Creek, Brandywine Creek, the Christina and the Delaware: about 75 river miles.

THE WAY DOWN, TO SCALE
Caln≈ 75 mi · Delaware Bay and the Atlantic Ocean
FROM THE CENTER OF CALN ≈ 75 mi to Delaware Bay and the Atlantic Ocean Beaver Creek → East Branch Brandywine Creek → Brandywine Creek → Christina → Delaware

Traced down the USGS NHDPlus V2.1 river network from the Census center point of Caln; river miles along the main stem, rounded.

MILE5
THE ALMANAC

Caln’s year

1991–2020 normals · records since 1992 · New Holland 2 SE, 17 mi west-northwest

Caln has a hot-summer humid continental climate. Summer afternoons average 86° in July; winter nights fall to about 24° in January. A normal year brings about 34 inches of snow; with the rain, that comes to about 47 inches of water.

39°24°42°25°51°32°63°42°73°53°81°62°86°66°84°65°77°58°65°47°54°36°43°29° JANFEBMARAPRMAYJUNJULAUGSEPOCTNOVDEC 12 TODAY CALN 46.8 in rain and snowmelt
Normal high to low, by month Record high to low, by day Rain by month Freezing
July, average86° / 66°high / low, the warmest month
January, average39° / 24°high / low, the coldest month
Rain and melted snow46.8 inwettest months: September and October
Snow a year33.5 insnowiest: February
Hottest on record105°FJuly 2, 2026
Coldest on record−13°FJanuary 19, 1994
Wettest day on record6.74 inOctober 9, 2005
Snowiest day on record26.0 inJanuary 23, 2016
90° days a year20very few reach 100°
Nights at or below 32°97and 19 days that stay below freezing
Climate typeHot-summer humid continentalKöppen Dfa

AROUND THE RING

1Freeze seasonfrom the first fall freeze, about Oct. 31, to the last in spring, about April 13 (median dates)
2Lows below freezingNov. 29 to March 18; normal lows fall below 32°
NOVEMBER 14 IN THE RECORD

On November 14 Caln normally reaches 54° and falls to 37°. The record high is 70°, in 1993; the record low 25°, in 2004. The most rain on this date, 0.50 in, fell in 2008.

MONTH BY MONTH
JanFebMarAprMayJunJulAugSepOctNovDec
Normal high39°42°51°63°73°81°86°84°77°65°54°43°
Normal low24°25°32°42°53°62°66°65°58°47°36°29°
Rain and melt, in3.342.784.113.563.524.504.434.274.904.563.183.69
Snow, inches10.310.65.51.20.00.00.00.00.00.31.04.6
Record high70° (2007)80° (2018)87° (1998)93° (2002)95° (2026)98° (2025)105° (2026)101° (2001)96° (2023)93° (2019)82° (2024)75° (1998)
Record low−13° (1994)−2° (2015)2° (2015)20° (2021)28° (2020)40° (2020)50° (2021)44° (2024)34° (2020)27° (1992)13° (2018)2° (2017)

Normals 1991–2020 and records since 1992 at New Holland 2 SE, 16 miles west-northwest, 260 ft higher. NOAA, through RCC-ACIS.

MILE7
ON THE NETWORK

Around Caln on the Forecast Network

Neighboring plates

Reading PA · 25 MI 25 miles north Philadelphia PA · 33 MI 33 miles east Baltimore MD · 66 MI 66 miles southwest Washington DC · 101 MI 101 miles southwest New York NY · 106 MI 106 miles northeast Hempstead NY · 122 MI 122 miles east
FORECASTCITY
Map of Caln, Pennsylvania. Explore the plate
PENNSYLVANIA · CHESTER

Caln

15,203 people, 340 ft above sea level in Chester County.

340 ftElevation
15,203People
9 sq miLand
Sunny 47°
SunnyDew point 29°
1

Today in Caln

NEXT 15 HOURS
Now mostly cloudy day 49° 0%
7p partly cloudy night 45° 1%
10p partly cloudy night 43° 1%
1a mostly clear night 41° 1%
4a mostly clear night 39° 1%
7a mostly sunny 39° 0%
Clear
NEXT RAINNone this week
→
Sat0%
Mostly cloudy Mostly cloudy
39
49
A
Sun0%
Mostly sunny Mostly sunny
36
54
A
Mon0%
Mostly sunny Mostly sunny
36
56
A
Tue0%
Sunny Sunny
38
59
A
Wed0%
Sunny Sunny
39
62
A
Thu0%
Mostly sunny Mostly sunny
41
64
A
Fri0%
Mostly sunny Mostly sunny
44
64
B
Letters show how sure the forecast is: A, models agree; B, some spread; C, check back. Sample data.
THIS WEEK, NINE YEARS AGO · NOV. 11, 2017

16°, the coldest this week of the year has been since 1992.

2

What Caln stands on

Caln’s center stands about 340 ft above sea level. Within three miles the land runs from 270 ft to 640 ft, a difference of 370 ft: rolling country. The highest named summit within 15 miles is Welsh Mountain, about 1,080 ft, 12 miles northwest.

Caln, northwest to southeast Caln340 ftWelsh Mountain1,080 ftWest Branch Brandywine Creekabout 200 ft ← NWSE → 24 miles through the town center; vertical exaggeration about 43×. Colors: rock at the surface.
Elevation, center340 ft
Within 3 miles270 to 640 ft
Lie of the landRolling (370 ft of relief)
High point nearbyWelsh Mountain, 1,080 ft, 12 mi northwest
5

Caln’s year

Caln has a hot-summer humid continental climate. Summer afternoons average 86° in July; winter nights fall to about 24° in January. A normal year brings about 34 inches of snow; with the rain, that comes to about 47 inches of water.

JANFEBMARAPRMAYJUNJULAUGSEPOCTNOVDEC 12 46.8 in
July, average86° / 66° · high / low, the warmest month
January, average39° / 24° · high / low, the coldest month
Rain and melted snow46.8 in · wettest months: September and October
Snow a year33.5 in · snowiest: February
Hottest on record105°F · July 2, 2026
Coldest on record−13°F · January 19, 1994
Wettest day on record6.74 in · October 9, 2005
Snowiest day on record26.0 in · January 23, 2016
90° days a year20 · very few reach 100°
Nights at or below 32°97 · and 19 days that stay below freezing
Climate typeHot-summer humid continental · Köppen Dfa
1Freeze season · from the first fall freeze, about Oct. 31, to the last in spring, about April 13 (median dates)
2Lows below freezing · Nov. 29 to March 18; normal lows fall below 32°
NOVEMBER 14 IN THE RECORD

On November 14 Caln normally reaches 54° and falls to 37°. The record high is 70°, in 1993; the record low 25°, in 2004. The most rain on this date, 0.50 in, fell in 2008.

Normals 1991–2020 and records since 1992 at New Holland 2 SE, 16 miles west-northwest, 260 ft higher. NOAA, through RCC-ACIS.
3

Where the rain goes

≈ 75 mito the AtlanticBeaver Creek → East Branch Brandywine Creek → Brandywine Creek → Christina → Delaware

A raindrop that lands in Caln reaches Delaware Bay and the Atlantic Ocean by way of Beaver Creek, East Branch Brandywine Creek, Brandywine Creek, the Christina and the Delaware: about 75 river miles.