Extreme Water Levels
Extremely high or low water levels at coastal locations are an important public concern and a factor in coastal hazard assessment, navigational safety, and ecosystem management. Exceedance probability—the likelihood that water levels will exceed a given elevation—is based on a statistical analysis of historic values. This interactive map provides annual and monthly exceedance probability levels for select NOAA Center for Operational Oceanographic Products and Services (CO-OPS) water level stations with at least 30 years of data. When used in conjunction with real-time station data, exceedance probability levels can be used to evaluate current conditions and determine whether a rare event is occurring. This information may also be instrumental in planning for the possibility of dangerously high or low water events at a local level. Because these levels are station-specific, their use for evaluating surrounding areas may be limited.