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

San Jose’s public GIS data gives an outline for every tax parcel, and its zoning map shows which blocks are zoned for single-family houses. We took the 122,664 tax parcels of 1,500 square feet or more whose center sits in a single-family (R-1) district, measured each lot from its outline, placed it in the neighborhood guides whose outlines contain its center, checked that center against FEMA’s flood map and checked each lot against CAL FIRE’s fire hazard severity zone maps. The city’s public data doesn’t list year built or house size, so this post is about the land: lot sizes, flood zones and fire zones. The figures come from City of San Jose parcel and zoning records, October 2026. There are no addresses or owner details here.

The short answer

• Citywide, the median R-1-zoned lot is 6,410 sq ft.
• Largest and smallest lots (guides with at least 150 single-family lots, apart from the five with large county areas noted with the table): largest in Almaden Country Club (10,910 sq ft), Stokes & Greylands (8,660 sq ft) and Crossgates (8,610 sq ft); smallest in Diridon & Delmas Park (4,970 sq ft), Rosemary Gardens & Rincon South (5,240 sq ft) and Plata Arroyo & Alum Rock Ave (5,360 sq ft).
• Flood zones: 4,363 of the 122,664 R-1-zoned lots (4%) have their parcel center in a FEMA high-risk flood zone (2,997 in AO, 673 in AH, 662 in AE and 31 in A). The most are in Willow Glen South & Lincoln Glen (648), River Glen & The Willows (516) and North Willow Glen & Gardner (329).
• Fire zones: 3,167 lots (3%) are at least partly in a CAL FIRE fire hazard severity zone, 1,323 High and 1,844 Moderate; none are in a Very High zone. The most High-zone lots are in Piedmont Hills & Sierramont (264), East Foothills (238) and Almaden Country Club (224).

Neighborhood by neighborhood

Largest median lot first. “Single-family lots” counts tax parcels in R-1 zoning whose center falls inside each guide’s outline. Each name opens its guide. Where two outlines share an edge, a handful of lots count in both rows, so the rows don’t add up to the city; the citywide row counts each lot once, including lots outside every guide. Baypointe & Zanker, Brokaw & Orchard, Narvaez & Hillsdale, River Oaks & Trimble, Silver Creek Valley and Vista Montaña & Riverview have fewer than 20 such lots, so they’re left out of the table; most homes there are in planned-development or other zoning districts.

Two more notes on the rows. Alum Rock, East Foothills, Burbank, Cambrian Park and Almaden Foothills & New Almaden take in large areas of unincorporated county land, which has no city zoning, so their rows describe only the city’s part. Most of Communications Hill is planned-development zoning; its 21 R-1 lots are mostly zoned R-1-1, one house per acre, which is why it tops the table.

What stands out

• Most flood-zone lots are in shallow-flooding zone AO: 2,997 of the 4,363 (69%), led by Willow Glen South & Lincoln Glen (646), River Glen & The Willows (516), North Willow Glen & Gardner (328) and Valley View-Reed (315).
• Zone AH, shallow ponding, concentrates in Overfelt Gardens & Las Plumas (237) and Canoas Garden & Willow Creek (192).
• Every R-1-zoned lot in Alviso has its parcel center in a high-risk zone: all 26, in zone AE.
• Lot sizes are fairly even: 70 of the 108 guides in the table have median lots between 6,000 and 7,000 sq ft.
• Fire zones are High or Moderate only. They touch lots in 19 guides; Piedmont Hills & Sierramont, East Foothills and Almaden Country Club hold 726 of the city’s 1,323 High-zone lots (55%).

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 68 guides in the table above 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 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.

Fire hazard zones, neighborhood by neighborhood

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 San Jose single-family lot touches a Very High zone, and the other 89 guides in the table above 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 city’s building department can say which apply to a specific address.

Reading it right

• Zoning isn’t use. We counted tax parcels of 1,500 square feet or more whose center is in an R-1-RR, R-1-1, R-1-2, R-1-5 or R-1-8 district; a few may hold a second unit, and single-family houses in planned-development (PD) and other districts 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 (zones A, AE, AH and AO). 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 flood level even in a high-risk zone; an elevation certificate settles it.
• 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

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

The San Jose data series: housing market by the numbers · neighborhoods ranked by price per sq ft · where homes sell over asking · ten years of prices by neighborhood · condos and townhomes · house prices by bedrooms · houses under $1.5M · houses at $2.5M and up · the best month to sell · the most expensive streets · our sales map

Thinking about a rebuild, an addition or a flood-zone house?

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.