Data current as of 2026-10-16 · Sourced from NOAA Storm Events
Over the past five years, the National Oceanic and Atmospheric Administration has recorded 3 hail storms within 25 miles of Union City, CA. The largest reported hail in this window was pea-sized, which can fracture shingle mat and dent metal flashing on contact. 2024 was the most active year on record locally, with 2 documented hail events.
Check Hail History for a Specific Address in Union City| Severity | Count | What it means for roofs |
|---|---|---|
| Minor | 3 events | Pea-size, unlikely to damage modern shingles |
| Year | Reported Hail Events Within 25 mi |
|---|---|
| 2026 | 1 event |
| 2024 | 2 events |
2024 was the busiest hail year on record locally for Union City, with 2 documented events inside the 25-mile radius. Storm activity in Union City typically peaks in spring and early summer, when the jet stream pushes Gulf moisture into the area and supercell thunderstorms become more frequent.
| Date | Location | Severity | Size | NOAA Comments |
|---|---|---|---|---|
| 2026-04-12 | 1 W Walnut Creek, CA | Minor | 0.25" | Resident in Walnut Creek reported pea-sized hail via Twitter (X) post. |
| 2024-03-30 | PIEDMONT, CA | Minor | 0.25" | Approximate location. Pea-sized hail was reported in the Walnut Creek area via social media. |
| 2024-03-30 | (SQL)SAN CARLOS ARPT, CA | Minor | 0.25" | Approximate location. Pea-sized hail was reported on by various parties on social media. |
NOAA has recorded 12 high-wind events within 25 miles of Union City, CA in the past five years. Of those, 10 reached severe-thunderstorm thresholds (58+ mph). The highest measured gust was 83 mph.
| Severity | Count |
|---|---|
| Severe | 6 events |
| Significant | 4 events |
| Moderate | 1 event |
| Minor | 1 event |
| Date | Location | Gust (mph) | Severity | NOAA Comments |
|---|---|---|---|---|
| 2026-04-12 | 2 NE Millbrae, CA | 49 | Significant | Corrects previous tstm wnd gst report from 2 NE Millbrae. KSFO reported a peak wind gust (via remarks) of 49 mph (43 knots) at 526 PM. |
| 2025-12-25 | (SFO)SFO INTL ARPT, CA | 73 | Severe | San Francisco International Airport reported a peak wind gust of 73 mph at 2:56 AM. Wind gusts above 58 mph were noted between 2:40 and 2:59 AM. |
| 2025-12-24 | PERMANENTE, CA | 67 | Severe | The PG&E station on Monte Bello Road West reported a gust of 67 mph. |
| 2025-12-24 | LOS ALTOS HILLS, CA | 75 | Severe | The PG&E station on Black Mountain reported a gust of 75 mph. |
| 2024-12-14 | (OAK)OAKLAND INTL AR, CA | 59 | Significant | A 59 mph gust was recorded at the Oakland International Airport at 5:51 AM Saturday. |
| 2024-12-14 | (SFO)SFO INTL ARPT, CA | 83 | Severe | A 83 mph gust was recorded at the San Francisco International Airport at 6:02 AM Saturday. |
| 2024-04-05 | WALNUT HGTS, CA | 58 | Significant | Tree down in roadway along Danville Boulevard near Walnut Creek. Time estimated via radar. |
| 2024-04-05 | SARANAP, CA | 58 | Significant | Powerlines were downed along Boulevard Way near Walnut Creek. |
| 2024-02-04 | EVERGREEN, CA | 23 | Minor | Three inch tree limbs were broken, and power lines were downed. |
| 2024-02-04 | SAN CARLOS, CA | 30 | Moderate | Three inch tree limbs were broken, and power lines were downed. |
| 2023-01-10 | (SFO)SFO INTL ARPT, CA | 69 | Severe | The ASOS weather station at the San Francisco International Airport reported a gust of 60 mph. |
| 2023-01-10 | BAYSHORE, CA | 70 | Severe | A roof was blown off an apartment building in South San Francisco. |
NOAA has not recorded a quarter-size-or-larger hail storm within 25 miles of Union City in the past five years. Smaller hail can still cause cosmetic damage, and unreported storms may exist.
Union City averages roughly 1 reported hail event per year within a 25-mile radius. Significant storms (quarter-size or larger) account for 0 of the 3 events recorded over the last five years.
The largest documented hail near Union City in the last five years was pea-sized. Most Union City-area hail falls in the marble-to-quarter range, with destructive storms (egg-size or larger) appearing roughly once every few years.
Most homeowners insurance policies in CA cover hail damage to roofs, siding, and gutters under the dwelling and other-structures coverage. Coverage typically requires the damage to be tied to a verifiable storm date — which is where the NOAA hail history above (and a HAAG-style test square validation) becomes important for the claim file.
Use the HailCheck address search to enter any street address in or near Union City. HailCheck returns every NOAA hail event within a configurable radius, along with severity bands, dates, and storm narratives for Pro members.
If your property in or near Union City took on hail during one of the storms above, the standard process for documenting damage is a 10×10 foot test square inspection. A HAAG-trained reviewer counts impact indicators — granule displacement, mat fractures, and bruising — within the marked square and produces a PASS or FAIL document for the claim file.
HailCheck offers a $99 photo-based HAAG-style test square validation. You submit photos from the field, our reviewer evaluates the impact indicators and cross-references the NOAA storm dates listed above, and a written PASS/FAIL determination is returned within one business day. We do not send anyone to the roof — the validation is built around the photos you submit.
Learn About $99 HAAG-Style ValidationUnion City sits east of the traditional hail alley, where hail events are less frequent than the central plains but tend to be associated with strong squall lines and tropical systems. Local roof systems are less commonly hardened for hail, which can mean even moderate impacts produce claim-worthy damage.