San Mateo Neighborhoods by Their Lots: Lot Sizes, Flood Zones and Fire Zones

The City of San Mateo’s public parcel layer gives an outline for every city parcel and the San Mateo County assessor’s property use code. We took the 17,738 city parcels with the county’s single-family use code, 1,500 square feet or more, measured each lot from its outline, placed it in our neighborhood guide outlines, checked its center against FEMA’s flood map and checked each lot against CAL FIRE’s fire hazard severity zone maps. The layer’s year-built and floor-area fields are empty, so this post is about the land: lot sizes, flood zones and fire zones. The figures come from the City of San Mateo parcel layer (city parcels only), downloaded October 2026; its use codes are the San Mateo County assessor’s, and the layer doesn’t say when they were last updated. There are no addresses or owner details here.

The short answer

• Citywide, the median single-family lot is 5,560 sq ft.
• Largest lots: San Mateo Park (10,300 sq ft), Laurelwood & Sugarloaf (7,700 sq ft) and Baywood & Aragon (6,360 sq ft).
• Smallest: Sunnybrae & 19th Avenue Park (4,720 sq ft), Mariner's Island & Lakeshore (4,950 sq ft) and Fiesta Gardens & Bay Meadows (5,020 sq ft).
• Flood zones: only 125 of the 17,738 single-family lots (1%) have their parcel center in a FEMA high-risk flood zone (112 in AO, 8 in AH and 5 in AE), all of them inside our guides; 73 are in San Mateo Village & Lauriedale and 39 in Fiesta Gardens & Bay Meadows.
• Fire zones: 532 lots (3%) are at least partly in a CAL FIRE fire hazard severity zone, all Moderate; none are High or Very High. Laurelwood & Sugarloaf has 396 of them.

Neighborhood by neighborhood

Largest median lot first. “Single-family lots” counts city parcels with the county’s single-family use code inside each guide’s outline. Each name opens its guide. The Highlands and most of Baywood Park & College Heights are unincorporated county land with San Mateo addresses, outside the city’s parcel layer, so they’re left out of the table; both guides give figures from the county’s parcel layer instead.

The “All of San Mateo” row also counts the 339 city lots outside the neighborhoods in the table, 330 of them in the city’s part of Baywood Park & College Heights.

What stands out

• San Mateo Park has the biggest lots by far: a median of 10,300 sq ft, about 1.9 times the citywide median.
• Flood zones are small and concentrated. San Mateo Village & Lauriedale and Fiesta Gardens & Bay Meadows hold 112 of the city’s 125 high-risk lots, all in shallow-flooding zone AO.
• Fire zones are concentrated too. In Laurelwood & Sugarloaf, 396 of the lots (46%) touch a Moderate zone; Beresford & Hillsdale has 69 and Baywood & Aragon has 66, and one is outside our guides.

Flood zones, neighborhood by neighborhood

Single-family lots in FEMA high-risk zones inside each guide’s outline, the share of the guide’s lots they make up, and the zones; most first. The other six guides in the table above have none.

What the flood zones mean

• Zone AE: a 1%-a-year chance of flooding, with a base flood elevation set.
• Zone AH: shallow ponding, usually 1 to 3 feet deep, with the same 1%-a-year risk and a base flood elevation.
• Zone AO: shallow flooding, usually sheet flow, 1 to 3 feet deep, with the same 1%-a-year risk; FEMA gives a flood depth instead of an elevation.
• Zone X: moderate to minimal risk, outside the 1%-a-year floodplain.
• Insurance: if the house itself is in an A or V zone, lenders on federally backed mortgages require flood insurance; a flood zone determination for the address settles it. In zone X it’s optional.

Reading it right

• A use code isn’t a zoning district. We counted parcels the county codes as single-family residences, 1,500 square feet or more; a few may hold a second unit, and townhomes and condos aren’t counted.
• Lot sizes are measured from the city’s parcel outlines, so they can differ from a survey by a few percent.
• We checked the center of each lot against FEMA’s National Flood Hazard Layer. A lot can straddle two zones, and maps change, so check the current FEMA map for the exact address.
• The flood zone covers the land, not the house. A house can sit above the base flood elevation even in a high-risk zone. An elevation certificate settles it and can lower the insurance price.
• Fire zones are the highest CAL FIRE fire hazard severity zone touching any part of the lot, from CAL FIRE’s 2025 map inside city limits (Local Responsibility Areas) and its State Responsibility Area map elsewhere, downloaded October 2026. The zone describes the land around a house, not how the house is built; CAL FIRE’s zone viewer shows any parcel.
• A median isn’t a verdict. It describes the lots, not which neighborhood is right for you.

Go deeper

San Mateo Housing Market by the Numbers covers prices and bidding, and The Most Expensive Streets in San Mateo goes street by street. Flood & Fire Zones by Neighborhood compares every guide we write, and the San Mateo city guide links every neighborhood guide.

Planning a rebuild or an addition?

A Property Nerd can pull the zoning, the lot, the flood and fire zones and the recent sales on your street before you plan. Call (408) 373-1660 or (650) 383-8606, or book a strategy call. Commissions are negotiable, and we offer bundled services, so ask us what’s included.