Herndon, Pennsylvania Weather
Cicadas claim the afternoon. Day 15 of summer. Read this microseason across nine climate regions →
Herndon weather forecast — hour by hour, 7-day outlook, NOAA radar
- TodayJul 5Light Showers54%0.47″87°69°—
- MondayJul 6Heavy Rain43%1.3″80°70°-7°
- TuesdayJul 7Light Drizzle39%—71°65°-9°
- WednesdayJul 8Light Drizzle25%—76°63°+5°
- ThursdayJul 9Overcast48%—92°68°+16°
- FridayJul 10Drizzle52%0.05″73°66°-19°
- SaturdayJul 11Overcast23%—83°63°+10°
AQI 66 (Moderate), driven by Ozone. AQI up 34 in the last 6 hours — air quality is degrading. Ozone at AQI 49 — peak already passed at 1 PM under overcast skies. Levels should ease through evening.
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 49 — peak already passed at 1 PM under overcast skies. Levels should ease through evening.
- Present
- AQI 49
- UV peak
- 0.8 at earlier today
- Sky at peak
- overcast
- Projected peak
- AQI 49
PM × Wind × Precip
PM scrubbed by 2 hours of recent rain — PM2.5 down to 5.5 µg/m³, PM10 to 5.8 µg/m³.
- PM2.5/PM10
- 0.95
- Wind
- calm
- Recent rain
- 2h in last 6h
- Pattern
- washed out
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
- 11:25 PM
- Moonset
- 11:16 AM
- In sign
- ♓︎ Pisces
Cicadas claim the afternoon
Herndon at a glance
- Today vs. normal: 16°F above the seasonal normal for this latitude
- Last frost: April 20 (climatological average for this latitude)
- Microseason: Jul 1–5
- Planting window: Harvest early potatoes. Begin drying onions on the surface.
ZIP code: 17830
16-Day Forecast — Herndon
- Sun87°69°54%
- Mon80°70°43%
- Tue71°65°39%
- Wed76°63°25%
- Thu92°68°48%
- Fri73°66°52%
- Sat83°63°23%
- Sun69°65°21%
- Mon78°64°23%
- Tue63°61°15%
- Wed73°61°19%
- Thu82°59°27%
- Fri84°60°25%
- Sat83°62°26%
- Sun81°63°29%
- Mon73°66°32%
Forecast data from Open-Meteo (CC BY 4.0).
Right now in the garden
Peak growing season
As of July 5, 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 — Herndon
SPC has placed Herndon in the Slight Risk category for severe thunderstorms today.
- TODAYSLGTSlight Risk
- TOMORROWTSTMGeneral Thunderstorms
- DAY 3NONENo severe risk
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 Herndon
- 17830