Old Mystic, Connecticut Weather
Fireflies rise from the lawn. Day 77 of spring. Read this microseason across nine climate regions →
Old Mystic weather forecast — hour by hour, 7-day outlook, NOAA radar
- TodayJun 4Clear——78°51°—
- FridayJun 5Overcast——85°53°+7°
- SaturdayJun 6Heavy Drizzle25%0.01″84°56°-1°
- SundayJun 7Showers31%0.04″84°58°0°
- MondayJun 8Overcast——73°51°-11°
- TuesdayJun 9Overcast——77°50°+4°
- WednesdayJun 10Mostly Clear——86°55°+9°
Ozone at AQI 85 — peak already passed at 1 PM under clear skies. AQI up 6 over the last 6 hours (gradual rise). 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 85 — peak already passed at 1 PM under clear skies. Levels should ease through evening.
- Present
- AQI 85
- UV peak
- 0.6 at earlier today
- Sky at peak
- clear
- Projected peak
- AQI 85
PM × Wind × Precip
PM2.5/PM10 ratio 0.69 with 9 mph wind — characteristic of long-range haze transport rather than a local source.
- PM2.5/PM10
- 0.69
- Wind
- light
- Recent rain
- 0h in last 6h
- Pattern
- transport
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).
A summer fog for fair, a winter fog for rain.
- Moonrise
- 3:20 AM
- Moonset
- 12:42 PM
- In sign
- ♒︎ Aquarius
Fireflies rise from the lawn
Old Mystic at a glance
- Today vs. normal: 4°F below the seasonal normal for this latitude
- Last frost: April 24 (climatological average for this latitude)
- Microseason: Jun 1–5
- Planting window: Harvest spring lettuce before it bolts. Sow heat-tolerant greens.
Right now in the garden
Peak growing season
As of June 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 Mystic
SPC has placed Old Mystic in the General Thunderstorms category for severe thunderstorms day after tomorrow.
- TODAYNONENo severe risk
- TOMORROWNONENo severe risk
- DAY 3TSTMGeneral Thunderstorms
Thunderstorms possible. Not severe, but capable of producing lightning and brief heavy rain.
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.
Planting calendar
| Month | Plant | Harvest |
|---|---|---|
| January | — | — |
| February | — | — |
| March | — | — |
| April | lettuce, peas, spinach, radishes | — |
| May | lettuce, peas, spinach, radishes, tomatoes, peppers, beans, squash | lettuce, peas, radishes |
| June | tomatoes, peppers, beans, squash | lettuce, peas, radishes |
| July | tomatoes, peppers, beans, squash | tomatoes, beans, summer squash |
| August | — | tomatoes, beans, summer squash |
| September | fall brassicas, garlic (overwinter), carrots | tomatoes, beans, summer squash |
| October | fall brassicas, garlic (overwinter), carrots | winter squash, tomatoes (last) |
| November | — | — |
| December | — | — |
A year in weather
Old Mystic's warmest month is July (~74°F mean) and its coldest is January (~30°F). Rainfall peaks in March (5.1 inches) and bottoms out in July (3.6 inches).
| Month | Mean temp | Precip | Rainy days |
|---|---|---|---|
| January | 30° | 3.9″ | 7 |
| February | 32° | 3.8″ | 6 |
| March | 39° | 5.1″ | 7 |
| April | 49° | 4.7″ | 7 |
| May | 59° | 3.6″ | 7 |
| June | 68° | 4.3″ | 6 |
| July | 74° | 3.6″ | 6 |
| August | 73° | 4.4″ | 6 |
| September | 65° | 4.8″ | 6 |
| October | 54° | 4.9″ | 6 |
| November | 44° | 4.2″ | 6 |
| December | 35° | 5.0″ | 7 |
Regional context
Old Mystic sits within a warm-summer humid continental climate region — a cohort that shares similar temperature ranges, seasonal patterns, and growing conditions across nearby cities.
Similar climates: Hartford, CT, Bridgeport, CT, New Haven, CT, Waterbury, CT, Danbury, CT.
Frequently asked
- When does it freeze in Old Mystic?
- Old Mystic's last spring frost typically falls around mid-April, and the first fall frost arrives around mid-November.
- What is the rainy season in Old Mystic?
- March is the wettest month with about 5.1 inches of rain on average; the city receives roughly 52 inches annually.
- What is the warmest month in Old Mystic?
- July is typically warmest, averaging about 74°F.
- What is the coldest month in Old Mystic?
- January is typically coldest, averaging about 30°F.
- When can I start a vegetable garden in Old Mystic?
- Cool-season crops (peas, lettuce) can be sown around the last spring frost (mid-April); warm-season crops (tomatoes, peppers) wait until 1–2 weeks after.
- How many rainy days does Old Mystic get?
- Old Mystic averages about 78 rainy days per year.
- What hardiness zone is Old Mystic?
- Old Mystic's USDA hardiness zone is determined by its lowest average winter temperature; check the USDA's online lookup with the city ZIP for the current zone designation.
Climate
Old Mystic, Connecticut sits in a warm-summer humid continental climate zone. January means hover near 30°F while July averages 74°F — a 45°F seasonal swing.
Across the year, Old Mystic receives about 52 inches of precipitation spread over roughly 78 rainy days.
The rhythm of the year is set by latitude (41.4°N), proximity to large water bodies, and elevation — all of which shape what grows here, when frost is likely, and what the weather story looks like day to day.