The temperature of Bay waters fluctuates with the seasonal changes in air temperature and solar radiation that warms the water. Temperature is an important habitat descriptor; the metabolism of most organisms increases as temperature increases, and many animals have life cycles (e.g. seasonal periods of reproduction or migration) that are cued to temperature change. This 20-year time series at USGS station 30 shows that surface water temperature usually fluctuates between about 9-10° centigrade (about 48° Fahrenheit) in winter and around 21° centigrade (70° Fahrenheit) in summer. Extremes in temperature were:

Plot Description:
1. Maximum water temperatures of 22.6° centigrade were measured in July 1985, August 1989, and in July 1992.

2. Minimum water temperature of 7.7° centigrade was recorded in January 1991.