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 4Heavy Rain67%0.83″95°72°—
- SundayJul 5Overcast50%—88°70°-7°
- MondayJul 6Light Drizzle88%—84°66°-4°
- TuesdayJul 7Heavy Drizzle83%0.03″71°65°-13°
- WednesdayJul 8Light Drizzle21%0.02″70°62°-1°
- ThursdayJul 9Light Drizzle16%—92°64°+22°
- FridayJul 10Light Drizzle61%—87°65°-5°
AQI 59 (Moderate), driven by Ozone. AQI down 10 over the last 6 hours (gradual decline). Ozone at AQI 43. Overcast through the UV peak window (cloud cover ~98%) — afternoon ozone should stay flat.
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 43. Overcast through the UV peak window (cloud cover ~98%) — afternoon ozone should stay flat.
- Present
- AQI 43
- UV peak
- 0.0 at 1 PM
- Sky at peak
- overcast
- Projected peak
- AQI 5
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: 3°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
- Sat95°72°67%
- Sun88°70°50%
- Mon84°66°88%
- Tue71°65°83%
- Wed70°62°21%
- Thu92°64°16%
- Fri87°65°61%
- Sat85°59°29%
- Sun81°59°23%
- Mon83°53°22%
- Tue89°59°18%
- Wed81°62°31%
- Thu83°59°27%
- Fri87°55°27%
- Sat87°67°42%
- Sun84°70°41%
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 Marginal Risk category for severe thunderstorms today.
- TODAYMRGLMarginal Risk
- TOMORROWMRGLMarginal Risk
- DAY 3TSTMGeneral Thunderstorms
Isolated severe storms possible. Limited threat for hail or damaging wind.
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