San Antonio, TX (78243) Flooding & Climate Risk Profile
The primary drivers of climate-related financial risk in San Antonio, TX (78243) are Inland Flooding, Tornado, and Hail. This area also faces an unusually high intensity for Heat Wave compared to national averages.
Understanding the Dollars
Expected Annual Loss (EAL) is a statistical average of property damage for this entire zip code over a standard year across all properties.
- / It represents the "average cost" rather than a guaranteed yearly bill.
- / It can be used to compare the relative risk from different hazards and across different neighborhoods.
Zip Code Risk Map
Flood Plain Analysis
Localized Flood Dynamics in 78243
FEMA Flood Maps for 78243 identify the "100-year" and "500-year" floodplains (1% and 0.2% annual chance), but modern climate risk analysis suggests that nearly 25% of flood insurance claims originate from properties outside of these designated high-risk zones.
Primary Risks
Inland Flooding
Expected Annual Loss for Zip Code 78243
Relatively High compared to US average
Tornado
Expected Annual Loss for Zip Code 78243
Very High compared to US average
Hail
Expected Annual Loss for Zip Code 78243
Relatively High compared to US average
Financial Risk Inventory
Recommended Mitigation Strategies
Recommended investments to protect your property value and reduce insurance liability based on your local risk profile.
Inland Flooding Mitigation
Install a smart sump pump with battery backup and extend downspouts 10ft from foundation.
Tornado Mitigation
Reinforce garage doors and consider a FEMA-approved safe room or storm cellar.
Hail Mitigation
Replace roof with Class 4 impact-resistant shingles to significantly lower insurance premiums.
Heat Wave Mitigation
Ensure attic insulation is R-49+ and consider a dual-fuel backup generator for AC.
Methodology and Sources
Spatial Climate Risk Modeling
The Expected Annual Loss (EAL) and hazard risk scores are derived from the FEMA NRI zip code dataset using a population-weighted spatial join. Because Zip Codes and Census Tracts do not share perfectly aligned boundaries, we utilize US Census Block Group population centroids to identify where residents actually live.
Financial & Insurance Metrics
The pysical resilence score is calculated by synthesizing Expected Annual Loss (EAL) against the total building replacement value within a jurisdiction. This creates a "Loss Ratio" that measures physical resilience. We supplement this with ZIP-code level data from the U.S. Treasury's Federal Insurance Office (FIO), monitoring trends in premium growth, loss ratios, and policy non-renewals to identify emerging "Insurance Deserts."
Primary Data Sources
- FEMA National Flood Hazard LayerHigh-resolution vector data for 100-year and 500-year flood zones.
- U.S. Department of the TreasuryFIO ZIP-code level insurance data (2018–2022 Historical Set).
- FEMA National Risk IndexBaseline hazard frequency and economic loss data (v1.20.0).
- U.S. Census BureauTIGER/Line 2025 Shapefiles & Decennial Population Statistics.