Hillsborough, CA— fire, flood & earthquake hazard information
Hillsborough is a city in San Mateo County in the San Francisco Bay Area, covering about 6.2 square miles. This page summarizes what official government maps show for Hillsborough: CAL FIRE fire hazard severity zones, FEMA flood zones, state seismic hazard zones, dam inundation areas, airport noise contours, and air-quality indicators. Figures are the share of Hillsborough’s area that falls inside each mapped zone.
View Hillsborough on the interactive map → to check any specific address, free.
Wildfire hazard severity zones
Per CAL FIRE's Fire Hazard Severity Zone maps, 37% of Hillsborough is in a Very High fire hazard severity zone, less than 1% is in a Moderate zone. The remainder of its area is outside currently designated zones.
| Very High severity zone | 37% |
| Moderate severity zone | less than 1% |
FEMA flood zones
less than 1% of Hillsborough lies within a FEMA Special Flood Hazard Area (1% annual chance, zones A/AE/AH/AO). Federally backed mortgages in a Special Flood Hazard Area generally require flood insurance.
| Special Flood Hazard Area (100-yr) | less than 1% |
Earthquake faults & seismic zones
The nearest mapped fault, the San Andreas fault zone, is about 1.5 mi (2.5 km) from the center of Hillsborough. 1 named fault trace in the USGS Quaternary fault database cross its boundary. 8% of its area is in a state-designated liquefaction zone of required investigation. 31% is in an earthquake-induced landslide zone.
| Nearest mapped fault | San Andreas fault zone — 1.5 mi (2.5 km) |
| Named fault traces crossing boundary | 1 |
| Liquefaction zone | 8% |
| Earthquake-induced landslide zone | 31% |
Dam inundation, aircraft noise & air quality
13% of Hillsborough lies within a state-reviewed dam-failure inundation area; annual average fine-particle (PM2.5) concentration across its census tracts is 8.3 μg/m³, and its composite pollution burden ranks around the 14th percentile statewide.
| Dam-failure inundation area | 13% |
| Annual PM2.5 (tract average) | 8.3 μg/m³ |
| Pollution burden percentile (statewide) | ~14 |
Frequently asked questions
- Is Hillsborough in a wildfire hazard severity zone?
- Per CAL FIRE's Fire Hazard Severity Zone maps, 37% of Hillsborough is in a Very High fire hazard severity zone, less than 1% is in a Moderate zone. The remainder of its area is outside currently designated zones.
- Is Hillsborough in a FEMA flood zone?
- less than 1% of Hillsborough lies within a FEMA Special Flood Hazard Area (1% annual chance, zones A/AE/AH/AO). Federally backed mortgages in a Special Flood Hazard Area generally require flood insurance.
- What earthquake faults and seismic zones affect Hillsborough?
- The nearest mapped fault, the San Andreas fault zone, is about 1.5 mi (2.5 km) from the center of Hillsborough. 1 named fault trace in the USGS Quaternary fault database cross its boundary. 8% of its area is in a state-designated liquefaction zone of required investigation. 31% is in an earthquake-induced landslide zone.
- How do I check a specific address in Hillsborough?
- Use the free sitelume interactive map at https://sitelume.com — search any Hillsborough address to see which mapped zones it falls in, layer by layer.
Nearby in San Mateo County
Sources: CAL FIRE Fire Hazard Severity Zones; FEMA National Flood Hazard Layer; USGS Quaternary Faults; CGS Seismic Hazard Zones & Alquist-Priolo zones; Cal OES dam inundation maps; county ALUC noise contours; CalEnviroScreen 4.0. Area shares are computed against each place’s Census TIGER boundary (last computed 2026-07-24). Boundaries and zone designations change; always verify with the issuing agency.