Climate Change and Flood Risk: What the Data Shows

Rising Flood Frequency

Data from NOAA and USGS show that flood events in the United States have become more frequent and more intense over the past several decades. The number of billion-dollar flood disasters has increased significantly since the 1980s, even after adjusting for inflation and development patterns.

Heavy rainfall events, defined as the top 1% of all daily precipitation totals, have increased by approximately 30% in the Northeast and 15% nationally since 1958. This means storms that produce flooding are becoming more common in many regions.

Sea Level Rise and Coastal Flooding

Sea levels along the U.S. coastline have risen 8-12 inches since 1920 and are projected to rise an additional 10-12 inches by 2050 under moderate scenarios. This directly increases the frequency and severity of coastal flooding, storm surge, and tidal flooding.

Cities like Miami, Charleston, Norfolk, and Annapolis already experience regular tidal flooding that was rare just 20 years ago. This chronic flooding damages infrastructure, reduces property values, and increases insurance costs even without major storm events.

Inland Flooding Changes

Warmer air holds more moisture, leading to more intense rainstorms. This affects inland communities that may not think of themselves as flood-prone. Urban areas are especially vulnerable because impervious surfaces prevent absorption, and aging stormwater systems were not designed for current rainfall intensities.

River flooding patterns are also shifting. Snowmelt is occurring earlier, rain-on-snow events are becoming more common, and the timing and magnitude of peak flows are changing in many watersheds.

What This Means for Homeowners

FEMA maps are based on historical data and may not fully reflect emerging risks. Forward-looking flood risk models from organizations like First Street Foundation suggest that many more properties face substantial flood risk than current FEMA maps indicate. Check your area's current flood data and consider that risk may increase over time when making long-term property decisions.