NHC HURDAT2 · SPC Tornado Database
Hurricanes and Tornadoes That Hit Portola Valley, CA
Every tropical system within 75 miles since 1851 and every tornado within 25 miles since 1950.
Data: NOAA NHC HURDAT2 and NOAA SPC tornado and hail reports, through 2025 · Updated
No tropical storm or hurricane has passed within 75 miles of Portola Valley, California since records began in 1851. Since 1950, 12 tornadoes have touched down within 25 miles, 0 of them rated EF3 or stronger.
- Hurricanes
- 0
- Tropical storms
- 0
- Tornadoes
- 12
- EF3 or stronger
- 0
within 75 mi, since 1851
below hurricane strength
within 25 mi, since 1950
no recorded deaths
What the records show for Portola Valley
The highest rating among the 12 tornadoes within 25 miles is F2, reached 2 times; the most recent, on May 5, 1998, came within 10 miles. Of the 12, none had a path within 5 miles of the city centre, and 2 have come since 2000. December has had the most tornadoes, 3. The most recent tornado was on December 14, 2024. Of the 705 California cities on this site, 52% have more tornadoes within 25 miles than Portola Valley. Hail has been reported within 10 miles 6 times since 2018, with stones up to 0.35 inches. Portola Valley has more hail reports within 10 miles than 69% of the 705 California cities.
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Tornadoes within 25 miles of Portola Valley
By decade
- 2020s1
- 2000s1
- 1990s6
- 1980s2
- 1950s2
| Date | Rating | Distance | Path | Killed / injured |
|---|---|---|---|---|
| May 5, 1998 | F2 | 10 mi | 0.6 mi | 0 / 1 |
| Jan 11, 1951 | F2 | 5 mi | 5.7 mi | 0 / 0 |
| Dec 14, 2024 | EF1 | 25 mi | 0.31 mi | 0 / 5 |
| Mar 20, 2005 | F1 | 22 mi | 3 mi | 0 / 0 |
| May 5, 1998 | F1 | 5 mi | 0.3 mi | 0 / 1 |
| Jan 14, 1980 | F1 | 20 mi | 0.3 mi | 0 / 1 |
| Apr 1, 1958 | F1 | 19 mi | 0.2 mi | 0 / 0 |
| Feb 7, 1998 | F0 | 14 mi | 0.2 mi | 0 / 0 |
| Feb 6, 1998 | F0 | 10 mi | 0.1 mi | 0 / 0 |
| Dec 8, 1997 | F0 | 19 mi | 0.2 mi | 0 / 0 |
| Dec 17, 1992 | F0 | 25 mi | 0.2 mi | 0 / 0 |
| Mar 10, 1986 | F0 | 20 mi | 0.2 mi | 0 / 0 |
The strongest 12 of 12, by rating and then by deaths. Ratings before February 2007 are on the original Fujita scale.
Hail in Portola Valley
The Storm Prediction Center has 6 hail reports within 10 miles of Portola Valley since 2018, made on 3 separate days. None of them reached 1 inch. The largest, 0.35 inches, fell on March 25, 2020, the most recent report.
Source: NOAA Storm Prediction Center severe weather reports, data through 2025.
Weather by month in Portola Valley
The nearest NOAA station with 1991–2020 climate normals is Skyline Ridge Preserve, CA, 5 miles south of Portola Valley at 2,270 feet. August is the warmest, with an average high of 81°F and low of 59°F; December is the coolest, at 54°F and 40°F. December is the wettest at 8.4 inches of precipitation on average and July the driest at 0.0 inches; the year adds up to 42.2 inches over 56 days with at least a tenth of an inch. Highs reach 90°F on about 13 days a year, almost all from June to September. Lows fall below freezing on about 11 nights a year. That 42.2 inches is more than at 206 of the 226 California stations used on this site (91%). Stanford, 4 miles northeast, has its own station (Palo Alto, CA): 15.2 inches a year, 27.0 less than here, and an August average high of 79°F against 81°F.
Water temperature at the NOAA tide station Redwood City, CA, 9 miles north, averaged 74°F in August and 54°F in January over 2021–2025. No month averaged 80°F. Sea level at the Redwood City tide gauge, 9 miles from Portola Valley, has risen 1.08 ± 0.25 inches per decade from 1974 to 2025, NOAA's linear trend; at that pace it is 10.8 inches in a hundred years. That is faster than at 62 of the 144 U.S. gauges with a NOAA trend.
| Month | High °F | Low °F | Precip. in | Days ≥ 0.1" | Water °F |
|---|---|---|---|---|---|
| Jan | 55 | 41 | 7.8 | 9 | 54 |
| Feb | 55 | 40 | 8.0 | 10 | 55 |
| Mar | 58 | 41 | 6.3 | 9 | 58 |
| Apr | 62 | 43 | 3.4 | 6 | 62 |
| May | 67 | 47 | 1.3 | 3 | 67 |
| Jun | 75 | 52 | 0.4 | 1 | 70 |
| Jul | 81 | 58 | 0.0 | 0 | 73 |
| Aug | 81 | 59 | 0.1 | 0 | 74 |
| Sep | 79 | 57 | 0.2 | 1 | 73 |
| Oct | 71 | 52 | 1.7 | 3 | 69 |
| Nov | 60 | 44 | 4.6 | 6 | 60 |
| Dec | 54 | 40 | 8.4 | 9 | 55 |
| Year | 66 | 48 | 42.2 | 56 | 64 |
Averages for 1991–2020 at Skyline Ridge Preserve, CA (2,270 ft), from NOAA NCEI U.S. Climate Normals; water temperature: average of hourly readings 2021–2025 at the NOAA tide station Redwood City, CA, from NOAA Tides & Currents. Normals describe the station; the farther a place is from it, and the bigger the difference in height, the more its weather can differ.
Floods, thunderstorm wind and lightning near Portola Valley
Since 1996, the National Weather Service has logged 51 flood, rain, thunderstorm wind and lightning events that began within 10 miles of Portola Valley: 40 floods, 5 thunderstorm wind reports, 2 flash floods, 2 heavy rain events and 2 lightning strikes. They killed 1 person and injured 0, and the NWS estimated $20.3 million in property and crop damage. The strongest thunderstorm gust on record here was 75 mph, on December 24, 2025.
December 31, 2005: flood 10 miles from the centre of Portola Valley — 1 killed, $7.0 million damage.
December 31, 2005: flood 10 miles from the centre of Portola Valley — $5.0 million damage.
January 1, 2006: flood 10 miles from the centre of Portola Valley — $5.0 million damage.
Source: NOAA NCEI Storm Events Database, events whose starting point is on record, 1996 to June 30, 2026. Damage is the NWS estimate in the dollars of the year, not insured losses, and NWS notes that some reports are unverified.
Flood insurance claims, disaster declarations and FEMA risk ratings
Flood insurance policyholders in Portola Valley's ZIP code 94028 have filed 34 claims with the National Flood Insurance Program since 1979, and were paid $1,000,000 for buildings and contents, in the dollars of each year. The most came from Pineapple Express - Southern in 1998: 12 claims (35% of all) and $699,000. 65% of the claims carry the name of a storm or flood event; the rest have no event name. Of the 415 California cities on this site with 10 or more claims, 171 have fewer than Portola Valley.
| Event | Claims | Paid |
|---|---|---|
| Pineapple Express - Southern1998 | 12 | $699,000 |
San Mateo County, which includes Portola Valley, has been named in 24 federal disaster or emergency declarations since 1977, 17 of them major disasters (by incident: 7 floods, 7 severe storms, 3 fires, 2 biological emergencies). The latest major disaster declaration was Severe Winter Storms, Straight-Line Winds, Flooding, Landslides, and Mudslides, on April 3, 2023. FEMA's National Risk Index gives San Mateo County a Relatively High rating for natural hazard risk overall; by hazard: Relatively High for inland flooding and coastal flooding; Relatively Moderate for lightning and heat waves; Relatively Low for tornadoes and strong wind; Very Low for hail. It models the county's expected loss from all 18 hazards it covers at $740.0 million a year, the 11th highest of 58 California counties; of the hazards above, the largest share, $212.3 million (29%), is from inland flooding.
Claims: FEMA, OpenFEMA Dataset FIMA NFIP Redacted Claims – v3, summed over ZIP codes; payments in the dollars of each year, not adjusted for inflation. Declarations: Disaster Declarations Summaries – v2, by county. Retrieved October 25, 2026. This product uses the Federal Emergency Management Agency's OpenFEMA API, but is not endorsed by FEMA. The Federal Government or FEMA cannot vouch for the data or analyses derived from these data after the data have been retrieved from the Agency's website(s).
Risk ratings: FEMA, National Risk Index county table, December 2025 (v1.20), retrieved October 26, 2026; ratings compare counties nationwide, are meant for planning and are no substitute for a local risk assessment. This product uses the Federal Emergency Management Agency's National Risk Index dataset API or downloadable datasets but is not endorsed by FEMA. The Federal Government or FEMA cannot vouch for the data or analyses derived from these data after the data have been retrieved from the Agency's website(s).
What counts as a pass, the distances and the sources: how this storm history is built.
Cities near Portola Valley
- Stanford, CA4 mi
- Menlo Park, CA6 mi
- Atherton, CA6 mi
- Los Altos, CA6 mi
- Palo Alto, CA6 mi
- Redwood City, CA7 mi
- Mountain View, CA7 mi
- San Carlos, CA9 mi
- Cupertino, CA10 mi
- Sunnyvale, CA10 mi
- Belmont, CA11 mi
- Saratoga, CA13 mi
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