Redwood City Neighborhoods by Their Lots: Lot Sizes, Flood Zones and Fire Zones

San Mateo County’s public parcel layer gives an outline and a property use code for every parcel. We took the 18,290 parcels with the county’s single-family use code, 1,500 square feet or more, inside our 13 Redwood City neighborhood guides, measured each lot from its outline, checked its center against FEMA’s flood map and checked each lot against CAL FIRE’s fire hazard severity zone maps. The layer has no year built, house size or city-limit line, so this post covers our 13 guides rather than the city as a whole. Emerald Hills, North Fair Oaks and Palomar Park are unincorporated San Mateo County with Redwood City addresses (North Fair Oaks has some Menlo Park addresses too), and the county layer covers them like the rest. Parcel outlines downloaded October 2026; the county’s use codes were last updated in June 2020. There are no addresses or owner details here.

The short answer

• Across our 13 Redwood City guides, the median single-family lot is 6,410 sq ft.
• Largest and smallest lots (guides with at least 150 single-family lots): largest in Palomar Park (20,960 sq ft), Emerald Hills (11,690 sq ft) and Edgewood Park (8,900 sq ft); smallest in Redwood Shores (4,910 sq ft), Greater Downtown (4,990 sq ft) and North Fair Oaks (5,490 sq ft).
• Flood zones: 240 of the 18,290 lots (1%) have their parcel center in a FEMA high-risk flood zone (219 in AE and 21 in A), 121 of them in Friendly Acres and 98 in Greater Downtown.
• Fire zones: 1,883 lots (10%) are at least partly in a CAL FIRE fire hazard severity zone, 377 High and 1,506 Moderate; none are Very High. Nearly all are in Emerald Hills and Palomar Park.

Neighborhood by neighborhood

Largest median lot first. “Single-family lots” counts parcels with the county’s single-family use code whose center falls inside each guide’s outline. Each name opens its guide. Emerald Hills and Farm Hill & Canyon share one lot along their edge, which counts in both rows; the “All 13 guides” row counts each lot once. Besides the three unincorporated guides, Horgan Ranch & Redwood Oaks, Farm Hill & Canyon and Mount Carmel & Eagle Hill each take in a pocket of unincorporated county land.

What stands out

• The hills have the biggest lots and nearly all the fire zones. Palomar Park (median lot 20,960 sq ft) and Emerald Hills (11,690 sq ft) hold 1,802 of the 1,883 lots in a fire zone; 96% of Emerald Hills’ lots and 84% of Palomar Park’s touch one.
• Flood zones concentrate in two neighborhoods. Friendly Acres (18% of its lots) and Greater Downtown (15%) hold 219 of the 240 high-risk lots, all in zone AE.
• Redwood Shores has the smallest lots of any guide (median 4,910 sq ft), and one of its 2,301 lots is in a high-risk flood zone.

Flood zones, neighborhood by neighborhood

Single-family lots in FEMA high-risk zones (A or AE) inside each guide’s outline, the share of the guide’s lots they make up, and the zones; most first. The other seven guides have none.

What the flood zones mean

• Zone A: a 1%-a-year chance of flooding, where FEMA hasn’t set a base flood elevation.
• Zone AE: the same 1%-a-year risk, with a base flood elevation set.
• 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.

Fire hazard zones

CAL FIRE maps how severe the wildfire hazard is across California, in three classes: Moderate, High and Very High. Single-family lots inside each guide’s outline, by the highest zone that touches any part of the lot; most High first. No lot touches a Very High zone, and the other 10 guides have none in any zone.

What the fire zones mean

• Hazard, not risk. CAL FIRE’s Office of the State Fire Marshal says the maps describe hazard: the physical conditions, like vegetation, terrain, fire history, embers and typical fire weather, over 30 to 50 years. They don’t count home hardening, defensible space or fuel reduction, which change the risk to a particular home (OSFM).
• Two kinds of map. Inside city limits (Local Responsibility Areas) we used CAL FIRE’s 2025 map; where the state is responsible for wildfire protection (State Responsibility Areas), its State Responsibility Area map. Land outside the three classes is shown as non-wildland or unzoned (OSFM).
• What a zone can bring. Depending on the zone and the kind of area, stricter building standards for new construction and additions, defensible-space rules, and a line on the seller’s natural hazard disclosure. The building department for the address (the city’s, or the county’s on unincorporated land) can say which apply.

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; the codes date from June 2020, so a few newer houses may be missing or coded otherwise, and townhomes and condos aren’t counted.
• Lot sizes are measured from the county’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.
• The fire zone describes the land around a house, not how the house is built or how the lot is kept. CAL FIRE’s zone viewer shows any parcel, and a seller’s natural hazard disclosure report states the zones for that property.
• A median isn’t a verdict. It describes the lots, not which neighborhood is right for you.

Go deeper

Redwood City Housing Market by the Numbers covers prices and bidding, The Most Expensive Streets in Redwood City goes street by street, and our Redwood City sales shows the homes we’ve sold there. Flood & Fire Zones by Neighborhood compares every guide we write, and the Redwood City guide page links every neighborhood guide.

Buying, selling or rebuilding in a flood or fire zone?

A Property Nerd can pull the zoning, the lot, the flood and fire zones, any elevation certificate and the recent sales on your street before you write an offer, set a price or plan a rebuild. 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.