Old Greenwich, Connecticut Weather
Cicadas claim the afternoon. Day 14 of summer. Read this microseason across nine climate regions →
Old Greenwich weather forecast — hour by hour, 7-day outlook, NOAA radar
- TodayJul 4Light Drizzle26%0.01″99°75°—
- SundayJul 5Rain72%0.30″85°72°-14°
- MondayJul 6Showers89%2.6″72°63°-13°
- TuesdayJul 7Drizzle71%0.14″64°58°-8°
- WednesdayJul 8Overcast16%—85°55°+21°
- ThursdayJul 9Light Drizzle17%—87°67°+2°
- FridayJul 10Light Drizzle39%—91°69°+4°
AQI 35 (Good), driven by PM2.5. AQI projected to climb to 60 over the next 6 hours. PM2.5 at 9.9 µg/m³ (AQI 52) with a 0.91 fine-to-coarse ratio and 6 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 during the projected peak around 7 PM.
What's driving it
Ozone × UV × Sky
Ozone at AQI 43 now. With UV 5.3 peaking around 1 PM under clear skies, surface ozone likely climbs to AQI 31 around 1 PM.
- Present
- AQI 43
- UV peak
- 5.3 at 1 PM
- Sky at peak
- clear
- Projected peak
- AQI 31
PM × Wind × Precip
PM2.5 at 9.9 µg/m³ (AQI 52) with a 0.91 fine-to-coarse ratio and 6 mph wind — combustion smoke trapped in calm air, not road dust.
- PM2.5/PM10
- 0.91
- 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
- 10:49 PM
- Moonset
- 9:56 AM
- In sign
- ♓︎ Pisces
Cicadas claim the afternoon
Old Greenwich at a glance
- Today vs. normal: 14°F above the seasonal normal for this latitude
- Last frost: April 22 (climatological average for this latitude)
- Microseason: Jul 1–5
- Planting window: Harvest early potatoes. Begin drying onions on the surface.
ZIP code: 06870
16-Day Forecast — Old Greenwich
- Sat98°75°26%
- Sun85°72°72%
- Mon72°63°89%
- Tue64°58°71%
- Wed85°55°16%
- Thu87°67°17%
- Fri91°69°39%
- Sat78°70°27%
- Sun71°67°28%
- Mon69°63°21%
- Tue75°63°22%
- Wed83°62°23%
- Thu95°72°27%
- Fri96°75°43%
- Sat85°75°43%
- Sun87°69°37%
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 — Old Greenwich
SPC has placed Old Greenwich in the Marginal Risk category for severe thunderstorms today.
- TODAYMRGLMarginal Risk
- TOMORROWTSTMGeneral Thunderstorms
- 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.
Beaches near Old Greenwich
- Jones Beach29.9 mi
Each linked page shows live water temperature, wave height, swim and surf verdicts, tides, and rip-current risk from NDBC + NOAA + NWS data.
ZIP codes in Old Greenwich
- 06870