The Derry 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 Derry
NWS forecast and National Blend of Models · updated 4:00 PM EDT
RIGHT NOWArnold Palmer Regional Airport (KLBE) · 3:47 PM
68°SunnyFeels like 68° · high of 71° near 4 PM
WindCalmno gusts
Humidity73%rising to 100% by morning
Pressure30.09 in →steady
Visibility10 mihaze-free
CloudsClear
UV index—no forecast
Dew point 59° · Comfortableabout the same for three days
DryComfortableStickyMuggyOppressive
NEXT RAIN
Friday, about 3 PMin about 70 hours · 84% chance · rain
LIKELY AMOUNT0.2–0.6 inmost likely 0.4; 1 in 10 over 1
LAST RAINSept. 220.27 in · 7 dry days
ALERTS & OUTLOOKS
No watches or warnings for Westmoreland County
NWS Pittsburgh and the Storm Prediction Center · checked 4:55 PM
SUN & MOON
↑ 7:11 AM7:03 PM ↓
11 h 52 m of daylight, 3 minutes less than yesterday
Waning gibbous, 88% lit. The Harvest Moon was full Saturday.
AIR & POLLEN
29
GOODAir quality index · fine particles
Tomorrow: 48, good. No pollen source yet.
The next three days, hour by hour
Sky: clear, cloudy, nightRain likelyNational Blend of Models
Forecast, with the range 8 in 10 ensemble members agree onNormal, about 80° / 62°
TUESept. 29Partly cloudy
71°53°
0% rain—WSW 0A
WEDSept. 30Partly cloudy
77°63°
10% rain—SW 4A
THUOct. 1Partly cloudy
80°67°
10% rain—SW 12B
FRIOct. 2Showers likely
77°51°
80% rain0.2–0.6″NNW 14C
SATOct. 3Partly cloudy; cooler
68°51°
30% rain—E 8B
SUNOct. 4Chance of showers
68°47°
30% rainup to 0.4″W 9C
MONOct. 5Mostly sunny
63°40°
0% rain—NNW 13C
How sure are we?AModels agree: highs within 4°BSome spread: within 8°CWide spread: check backRange from the National Blend of Models percentiles · graded on Forecast Scores
AIR MAIL
Where today’s air came from
The air arriving over Derry about 5,000 feet above the ground was over the Atlantic off the Carolinas three days ago, and over the Great Lakes a day ago, about 1,610 miles back along its path. The nine paths traced from around the city fan out, so treat that as a best guess. Near the ground the air came from the western Atlantic; at 10,000 feet, from the Atlantic off the Carolinas. Traced back 72 hours through NOAA’s hourly RAP analyses and the GFS beyond them, nine paths at each of three heights.