Mercersburg, Pennsylvania Weather
Cicadas claim the afternoon. Day 14 of summer. Read this microseason across nine climate regions →
Mercersburg weather forecast — hour by hour, 7-day outlook, NOAA radar
- TodayJul 4Rain26%0.23″99°72°—
- SundayJul 5Heavy Rain85%0.58″92°73°-7°
- MondayJul 6Heavy Showers85%0.57″78°66°-14°
- TuesdayJul 7Overcast67%—76°63°-2°
- WednesdayJul 8Overcast16%—84°59°+8°
- ThursdayJul 9Overcast42%—92°63°+8°
- FridayJul 10Light Drizzle36%—88°69°-4°
AQI 55 (Moderate), driven by PM2.5. AQI flat over the last 6 hours (within ±3 points). PM2.5 at 10.8 µg/m³ (AQI 54) with a 0.92 fine-to-coarse ratio and 4 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.
What's driving it
Ozone × UV × Sky
Ozone at AQI 48 now. With UV 4.0 peaking around 1 PM under clear skies, surface ozone likely climbs to AQI 26 around 1 PM.
- Present
- AQI 48
- UV peak
- 4.0 at 1 PM
- Sky at peak
- clear
- Projected peak
- AQI 26
PM × Wind × Precip
PM2.5 at 10.8 µg/m³ (AQI 54) with a 0.92 fine-to-coarse ratio and 4 mph wind — combustion smoke trapped in calm air, not road dust.
- PM2.5/PM10
- 0.92
- Wind
- calm
- 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).
If the first of July be rainy weather, 'twill rain more or less for four weeks together.
- Moonrise
- 11:05 PM
- Moonset
- 10:15 AM
- In sign
- ♓︎ Pisces
Cicadas claim the afternoon
Mercersburg at a glance
- Today vs. normal: 9°F above the seasonal normal for this latitude
- Last frost: April 15 (climatological average for this latitude)
- Microseason: Jul 1–5
- Planting window: Harvest early potatoes. Begin drying onions on the surface.
ZIP code: 17236
16-Day Forecast — Mercersburg
- Sat99°72°26%
- Sun92°73°85%
- Mon78°66°85%
- Tue76°63°67%
- Wed84°59°16%
- Thu92°63°42%
- Fri88°69°36%
- Sat87°69°35%
- Sun80°67°27%
- Mon80°64°18%
- Tue76°64°12%
- Wed88°66°23%
- Thu93°68°21%
- Fri95°73°34%
- Sat81°72°39%
- Sun89°68°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 — Mercersburg
SPC has placed Mercersburg 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.
ZIP codes in Mercersburg
- 17236