Connecticut Coastal Towns Storm Annual Exceedance Probability/Return Interval Viewer

Annual exceedance probability (AEP) refers to the probability of a flood event occurring in any year. A return interval is the average time between flood events. For example, the return interval of a flood might be 100 years; otherwise expressed as its probability of occurring being 1/100, or a 1% chance in any one year.

This viewer presents the projected storm surge water levels and significant wave heights, which may contribute to a better understanding of extreme storms to guide decision-makers. The anticipated sea level of 20 inches by 2050 can be added to the current (2020) flood scenarios generated in the table for each town entered below. More information on the methodology is presented in the Documents.

To use the viewer, please click on the drop-down menu to chose the town. Different projections of storm surge and significant wave height projections will activate automatically for different towns. The user can compare different towns by Add Town option.

To navigate through the drop-down viewer, please use

Data Description and Usage

The results presented here are the modeled storm surge water levels using coupled coastal circulation and wave model (FVCOM-SWAVE, finite-volume coastal ocean model with the version of the Simulating Wave Nearshore) to hindcast the 44 highest storms between 1950-2018. The floodwater elevation for the different annual exceedance probabilities is calculated empirically using a Poisson-GPD fit. The storm surge water level and significant wave height represented as (h) and (Hs), respectively. The total water level is the summation of the storm surge water level and significant wave height. The return period of the storm events presented is 10, 30, 100, and 500-year with 10%, 3.33%, 1%, and 0.2% annual exceedance probability storms, respectively.


This information is provided with the understanding that it is not guaranteed to be correct or complete and conclusions drawn from such information are the sole responsibility of the user. Attempts have been made to ensure that this data or documentation is accurate and reliable; The University of Connecticut, nor the Department of Marine Sciences, does not assume liability for any damages caused by inaccuracies in this data or documentation, or as a result of the failure of the data or software to function in a particular manner. The University of Connecticut, nor the CIRCA, makes no warranty, expressed or implied, as to the accuracy, completeness, or utility of this information, nor does the fact of distribution constitute a warranty.