United States · 1991–2020

Best time to visit
Deep River Center.

September leads for comfortable weather in Deep River Center: typically 23.1°C by day, 13.8°C at night, with 88 mm of rain. Based on measured 1991–2020 NOAA station history.

Best comfortSeptember

Typical high23.1°C

Typical low13.8°C

Rain in September88 mm

Comfort

September

September · June · August

85climate match

Beach

July

July · August · September

73climate match

Outdoors

May

May · October · September

77climate match

The weakest month is January, scoring 5 against September’s 85 — days reach only 3.3°C, 21° below the 24°C the score treats as ideal.

Month by month

The whole year,
without the guesswork.

The bars show the comfort score. Day and night temperatures come from daily observed highs and lows; rain is the historical monthly estimate.

Jan

53.3° / -5.2°

Feb

54.5° / -4.4°

Mar

88.1° / -1°

Apr

3213.4° / 3.8°

May

5718.3° / 9.1°

Jun

8323° / 14.3°

Jul

7826.4° / 18°

Aug

7926.3° / 17.7°

Sep

8523.1° / 13.8°

Oct

5317.3° / 7.8°

Nov

2912° / 2.5°

Dec

56.6° / -1.9°

Monthly climate evidence for Deep River Center — daylight is calculated from latitude, everything else is measured, sea temperature from the nearest open water 29 km away
Month	Day	Night	Rain	Wet days	Sea	Daylight	Comfort	Coverage
January	3.3°C	-5.2°C	58 mm	6.6	5.0°C	9 h 29	5	Good coverage
February	4.5°C	-4.4°C	52 mm	6.1	3.2°C	10 h 33	5	Good coverage
March	8.1°C	-1°C	90 mm	6.8	3.8°C	11 h 48	8	Good coverage
April	13.4°C	3.8°C	90 mm	8.5	6.7°C	13 h 16	32	Good coverage
May	18.3°C	9.1°C	89 mm	9	11.3°C	14 h 29	57	Good coverage
June	23°C	14.3°C	90 mm	7.9	16.4°C	15 h 09	83	Good coverage
July	26.4°C	18°C	77 mm	6.5	20.7°C	14 h 53	78	Good coverage
August	26.3°C	17.7°C	75 mm	5.9	21.8°C	13 h 50	79	Good coverage
September	23.1°C	13.8°C	88 mm	5.6	20.5°C	12 h 25	85	Good coverage
October	17.3°C	7.8°C	93 mm	7	17.3°C	11 h 01	53	Good coverage
November	12°C	2.5°C	76 mm	7	12.8°C	9 h 48	29	Good coverage
December	6.6°C	-1.9°C	81 mm	7.6	8.6°C	9 h 12	5	Good coverage

Records at GROTON NEW LONDON AP, 1999–2026
Month	Record high	Record low	Wettest day	Wettest / driest month	Years
January	18.9°C12 Jan 2020	-21.6°C16 Jan 2009	56 mm5 Jan 2019	164 mm2024 · driest 8 mm in 2018	27
February	21.7°C16 Feb 2023	-22.1°C14 Feb 2016	43 mm13 Feb 2008	106 mm2022 · driest 12 mm in 2015	27
March	23.3°C18 Mar 2011	-15.5°C6 Mar 2015	87 mm30 Mar 2010	308 mm2010 · driest 15 mm in 2006	27
April	30.0°C26 Apr 2009	-5.5°C2 Apr 2019	82 mm13 Apr 2004	176 mm2004 · driest 19 mm in 2015	27
May	33.9°C31 May 2022	-1.0°C1 May 2008	83 mm12 May 2006	185 mm2006 · driest 27 mm in 2015	27
June	33.9°C25 Jun 2025	4.4°C1 Jun 2001	115 mm7 Jun 2013	213 mm2013 · driest 12 mm in 2016	27
July	38.3°C6 Jul 2010	10.0°C11 Jul 2002	118 mm1 Jul 2009	246 mm2009 · driest 0 mm in 2025	27
August	33.9°C14 Aug 2016	7.8°C28 Aug 2025	82 mm28 Aug 2006	173 mm2006 · driest 29 mm in 2021	26
September	32.2°C4 Sep 2018	2.2°C29 Sep 2000	70 mm6 Sep 2008	185 mm2008 · driest 0 mm in 2007	26
October	30.6°C2 Oct 2019	-4.3°C19 Oct 2015	118 mm14 Oct 2005	324 mm2005 · driest 0 mm in 2018	26
November	26.1°C7 Nov 2022	-11.0°C23 Nov 2018	49 mm22 Nov 2005	147 mm2018 · driest 2 mm in 2012	26
December	18.9°C1 Dec 2001	-14.4°C21 Dec 2004	75 mm11 Dec 2024	179 mm2023 · driest 13 mm in 2017	27

Typical days per month at GROTON NEW LONDON AP, 1991–2020
Month	Days 25°C+	Days 30°C+	Frost nights	Heavy rain (10 mm+)
January	0	0	25	2
February	0	0	24	2
March	0	0	19	2
April	<1	0	5	3
May	2	0	<1	3
June	10	1	0	3
July	22	4	0	3
August	23	3	0	2
September	8	<1	0	3
October	<1	<1	2	3
November	0	0	10	3
December	0	0	21	3

How often, not how much — every day in GROTON NEW LONDON AP’s record sorted by what it was actually like, rather than averaged
Month	Warm & dry days	Wet days	Washouts	Week with 3+ wet days	Daytime mean has ranged
January	0%	22%	7%	17%	0.8–6.2°C
February	<1%	23%	6%	24%	1.5–7.4°C
March	<1%	24%	9%	23%	6.1–11.3°C
April	8%	28%	9%	31%	11.6–15.1°C
May	30%	29%	10%	35%	17.2–19.7°C
June	66%	25%	8%	27%	22.2–24.5°C
July	79%	21%	8%	19%	24.6–28.4°C
August	81%	19%	7%	16%	25.1–27.6°C
September	71%	19%	9%	17%	21.8–24.4°C
October	24%	23%	9%	22%	15.9–19.2°C
November	3%	23%	8%	23%	10.3–14.1°C
December	0%	25%	10%	26%	4.2–9.3°C

A warm and dry day reaches 20°C with under 1 mm of rain; a wet day gets 1 mm or more; a washout gets 10 mm or more. The week column is the share of seven-day stretches in that month, across the station’s whole daily record, that contained three or more wet days — the odds a week-long trip is rained on repeatedly, counted rather than modelled. The last column is the 10th to 90th percentile of that month’s daytime average across individual years: a narrow band means the average is what you will get, a wide one means the average is a midpoint between years that felt quite different.

2000Each stripe is one year’s mean temperature against the 26-year average. Warmest: 2023. Coolest: 2003.2025

The evidence behind this page

Nearby, measured,
and named.

Place identity: GeoNames 7257361
NOAA station: USW00014707 · GROTON NEW LONDON AP
Station distance: 33.1 km from the place centre
Climate period: 1991–2020
Minimum month coverage: 21 usable years
Daylight: Calculated from latitude 41.38°, mid-month, sunrise to sunset including refraction. Not a station measurement.
Sea temperature: NOAA OISST v2.1 1991–2020 monthly climatology, nearest open water 29 km from the place centre. A sheltered bay can run warmer than the open sea it is measured from.
Important limit: Historical climate is not a forecast. Nearby stations can miss mountains, coasts, and local microclimates.

These places read the same station, so their numbers are identical — distance from GROTON NEW LONDON AP is what differs

Waterford→Old Saybrook→Niantic→Central Waterford→Essex Village→Westbrook Center→

Or put two places side by side: Deep River Center vs Waterford

Best time to visitDeep River Center.

September

July

May

The whole year,without the guesswork.

Nearby, measured,and named.

Best time to visit
Deep River Center.

The whole year,
without the guesswork.

Nearby, measured,
and named.