Mystic, CT weather in September
In September, Mystic sees highs around 74°F and lows around 58°F: mild, with frequent rain. Rain falls on about 10 days.
- Normal high
- 74°F
- Normal low
- 58°F
- Wet days
- 10
- 4.3 in total
- Muggy days
- 7
- dew point 65°F+
How September changes from start to finish
| September 1 | September 30 | |
|---|---|---|
| Normal high | 78°F | 69°F |
| Normal low | 63°F | 53°F |
| Chance of a wet day | 31% | 35% |
| Sunrise / sunset | 6:14 am / 7:21 pm | 6:43 am / 6:32 pm |
| Daylight | 13.1 h | 11.8 h |
Chance of a wet day: average for the first and last 7 days of the month. Times are local clock time (Eastern Time).
A typical September day
- 6 am59°Fdew point 55°F
- 9 am67°Fdew point 57°F
- Noon72°Fdew point 56°F
- 3 pm73°Fdew point 56°F
- 6 pm67°Fdew point 57°F
- 9 pm63°Fdew point 57°F
NOAA hourly normals (local standard time) from Providence T F Green Airport (38 mi away); average wind 8 mph.
What kind of days to expect
- Comfortable dayshigh 65-80°F and dew point under 60°Fnot available
- Beach dayshigh 80-95°F, under 0.05 in of rain, afternoon wind under 15 mph4 of 30
- Hot dayshigh 90°F or more0 of 30
- Muggy daysdaily mean dew point 65°F or more7 of 30
- Wet daysat least 0.01 in of rain or melted snow10 of 30
- Notable rainat least 0.10 in6 of 30
- Freezing nightslow 32°F or below0 of 30
- Snow on the groundsnow depth 1 in or more0 of 30
Average days per September, counted from daily records for each year 1991-2020.
Rain in September
Normal precipitation is 4.3 in; a dry September brings about 3.0 in and a wet one about 5.4 in (25th and 75th percentiles). About 3 days bring half an inch or more, and about 1 an inch or more.
How September varies from year to year
- Warmest September, 1991-20202015: average high 78°F
- Coolest September1992: average high 70°F
- Wettest September2008: 9.9 in
- Driest September2014: 0.9 in
- Highest reading91°F (September 1, 2010)
- Lowest reading32°F (September 30, 2000)
From the station's daily records with NOAA quality flags removed; most recent date shown when a reading repeats.
September compared with August and October
| August | September | October | |
|---|---|---|---|
| Normal high | 80°F | 74°F | 63°F |
| Normal low | 65°F | 58°F | 47°F |
| Wet days | 9 | 10 | 10 |
| Comfortable days | – | – | – |
| Daylight | 13.8 h | 12.5 h | 11.1 h |
Highs change by -6°F from August and -11°F into October.
Nearby alternatives in September
- Warmer: Philadelphia, PA194 mi · high 79°F · 9 wet days
- Cooler: Lake Placid, NY226 mi · high 66°F · 12 wet days
How Mystic ranks in September
- Normal high304th warmest of 378 cities; 5th of 5 in Connecticut
- Wet days318th driest of 378
What to pack for Mystic in September
- A rain jacket or umbrella – rain on about 10 days
Heating and cooling
September has 67 heating degree days and 91 cooling degree days (base 65°F), 3% of the year's total heating and cooling demand.
Questions
How hot is Mystic in September?
The normal high is 74°F and the normal low is 58°F. From 1991 to 2020 the hottest September reading was 91°F (September 1, 2010).
Does it rain a lot in Mystic in September?
About 10 days in September have at least 0.01 in of precipitation, and the normal total is 4.3 in. The wettest September in 1991-2020 was in 2008 (9.9 in); the driest was in 2014 (0.9 in).
Where the numbers come from
- Temperature, rain, snowfall and snow depth: Groton (USC00063207), 3.7 mi W of the city center, 40 ft . NOAA normals and daily records, 1991-2020.
- Frost dates: Groton New London Airport (USW00014707), 4.7 mi WSW of the city center, 10 ft . NOAA normals and daily records, 1991-2020.
- Humidity and wind by hour: Providence T F Green Airport (USW00014765), 38 mi NE of the city center, 60 ft (52 ft higher than the city). NOAA normals and daily records, 1991-2020.
- Daily humidity and wind: Groton-New London Airport (725046-14707), 4.7 mi WSW of the city center, 8 ft . Hourly observations, 1991-2020.
- Not available for this location: cloud cover (no station close enough or similar enough in elevation).