Photos of the Long Island Sound

Research & Monitoring

Status and Trends: LISS Environmental Indicators

Water Temperature

Regional Long-Term Mean Winter Water Temperatures

Jim O'Donnell/University of Connecticut/image by Lucy Reading-Ikkanda

Millstone Environmental Lab, Waterford CT

Near Surface Water Temperature in Niantic Bay
Winter Spring Summer Fall
1976 3.94 11.14 18.94   9.69
1977 1.32 10.72 19.61 11.49
1978 1.95   9.40 18.91 12.11
1979 3.17 10.67 19.93 12.33
1980 3.47 10.53 19.61 10.69
1981 2.34 10.69 20.11 10.70
1982 2.29   9.88 19.69 12.46
1983 4.65 10.87 19.61 12.61
1984 4.29 10.99 19.68 12.84
1985 3.67 10.98 20.22 12.85
1986 4.06 11.52 19.43 12.38
1987 4.40 11.56 19.66 11.32
1988 3.28 10.79 19.16 11.17
1989 3.82 10.68 19.72 10.97
1990 4.28 10.83 19.89 13.16
1991 5.38 12.32 20.00 12.48
1992 4.45 10.98 19.08 11.19
1993 3.79 11.03 19.91 11.85
1994 2.55 10.64 20.13 12.87
1995 5.31 11.35 20.26 12.87
1996 2.86   9.71 18.74 10.90
1997 3.71   9.84 18.82 11.04
1998 4.65 11.53 19,99 12.21
1999 4.97 12.55 20.85 13.15
2000 4.19 11.76 20.45 12.38
2001 4.26 11.54 20.45 13.55
2002 5.67 11.96 20.83 12.09
2003 2.40 10.50 20.33 12.40
2004 3.19 11.55 19.98 12.08
2005 3.22 11.03 20.27 12.52
2006 5.70 12.05 20.46 13.75
2007 4.99 11.29 20.25 13.25
2008 5.38 11.93 20.67 12.51
2009 4.05 11.43 19.92 12.04
2010 3.83 13.04 20.82 11.56
2011 3.02 11.30 20.43 13.45
2012 7.22 13.80 21.91 13.04
2013 4.65 11.95 21.19 12.92
2014 3.44 11.39 20.58 12.56
2015 2.22 11.27 22.19 14.36

What is The Temperature Indicator?

We use two different temperature indicators here to try to improve our understanding of decadal and long term chances in water temperature.  The long term winter average temperature shows us relative temperature change at several stations throughout the region over time.  It helps us see the decade scale up and down swings in the regional data, as well as the overall year to year variability.  We choose winter temperature because it is less impacted by daily weather patterns and station locations.  In the summer, there can be several degrees of difference between a nearshore or offshore station, and/or a cloudy vs. sunny day, which is much larger than the year to year signal.  but in the winter, LIS is a pretty uniform temperature.
The other dataset shows seasonal averages in Niantic Bay.  This dataset is much shorter, but higher resolution.  By clicking the individual seasons on or off in the legend, you can more clearly see the patterns within each season 

 

HOW IS THIS TEMPERATURE DATA COLLECTED?

Near surface water temperature has been measured regularly for the last 30 years in Niantic Bay by the Millstone Environmental Lab.  Each year, temperatures are reported as seasonal averages.  This data set represents the longest continuous record of water temperatures in Long Island Sound.  The long term winter graph shows several longer datasets from throughout the region.  In most cases, these measurements are taken at least weekly from near surface inshore waters in the vicinity of various laboratory facilities

STATUS

Average seasonal water temperatures have been slowly but steadily increasing at this location in Long Island Sound.  Winter temperatures appear to be increasing more rapidly than spring, summer or fall temperatures, and winter 2012 is the warmest since the inception of this record by a large margin.  Increases in surface water temperatures have been linked to observed changes in the fish community.  Cold-adapted fish have been observed less frequently in recent years, while warm-adapted fish have been observed more frequently.  The combination of increasing water temperatures and changing fish community is believed to be indicative of climate change. The overall mean from 1976 through 2015 is 3.90°C  (39.02 F) for winter, 11.22°C (52.20F) for spring, 20.07°C (68.13F) for summer, and 12.24°C (54.03F) for fall.

DATA NOTES

Winter defined as January-March, spring as April-June, summer as July-September, and fall as October-December.

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