Williston, Maryland Weather
Cicadas claim the afternoon. Day 14 of summer. Read this microseason across nine climate regions →
Williston weather forecast — hour by hour, 7-day outlook, NOAA radar
- TodayJul 4Light Drizzle15%—103°80°—
- SundayJul 5Overcast21%—99°78°-4°
- MondayJul 6Thunderstorm73%1.3″92°73°-7°
- TuesdayJul 7Heavy Drizzle68%—89°70°-3°
- WednesdayJul 8Drizzle35%—79°69°-10°
- ThursdayJul 9Overcast10%—91°68°+12°
- FridayJul 10Overcast35%—96°72°+5°
AQI 140 (Unhealthy for Sensitive Groups), driven by Ozone. AQI up 87 in the last 6 hours — air quality is degrading. Ozone at AQI 98. Overcast through the UV peak window (cloud cover ~86%) — afternoon ozone should stay flat.
CAUTION Sensitive groups (children, elderly, respiratory conditions) should limit prolonged outdoor exertion.
What's driving it
Ozone × UV × Sky
Ozone at AQI 98. Overcast through the UV peak window (cloud cover ~86%) — afternoon ozone should stay flat.
- Present
- AQI 98
- UV peak
- 0.1 at 1 PM
- Sky at peak
- overcast
- Projected peak
- AQI 12
PM × Wind × Precip
PM2.5 at 9.8 µg/m³ (AQI 52) with a 0.93 fine-to-coarse ratio and 5 mph wind — combustion smoke trapped in calm air, not road dust.
- PM2.5/PM10
- 0.93
- Wind
- light
- 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
- 10:55 PM
- Moonset
- 10:08 AM
- In sign
- ♓︎ Pisces
Cicadas claim the afternoon
Williston at a glance
- Today vs. normal: 27°F above the seasonal normal for this latitude
- Last frost: April 9 (climatological average for this latitude)
- Microseason: Jul 1–5
- Planting window: Harvest early potatoes. Begin drying onions on the surface.
16-Day Forecast — Williston
- Sat103°80°15%
- Sun99°78°21%
- Mon92°73°73%
- Tue89°70°68%
- Wed79°69°35%
- Thu91°68°10%
- Fri96°72°35%
- Sat92°74°35%
- Sun85°73°24%
- Mon80°68°18%
- Tue88°67°15%
- Wed93°70°34%
- Thu92°72°35%
- Fri93°71°32%
- Sat95°71°35%
- Sun93°76°43%
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 — Williston
SPC has placed Williston in the Enhanced Risk category for severe thunderstorms today.
- TODAYENHEnhanced Risk
- TOMORROWSLGTSlight Risk
- DAY 3TSTMGeneral Thunderstorms
Numerous severe storms likely. Tornadoes, large hail, and damaging wind gusts possible across the area. Track NWS warnings if storms develop.
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 Williston
- 21629