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Union City, California Weather

Summer solstice light stretched thin. Day 88 of spring. Read this microseason across nine climate regions →

Union City weather forecast — hour by hour, 7-day outlook, NOAA radar

Union City, CA
Monday, June 15 at 7:01 AM
58
°
Overcast
Feels like
59°
Humidity
94%
Wind
3 mph
Sunrise
10:46 PM
Sunset
1:31 PM
Union City, CA
Hour by hour · 24h
24-Hour ForecastUnion City, CA: 24-hour forecast. Temperatures range from 54 to 75 degrees Fahrenheit.
L 54°H 75°
Union City, CA
7-day forecast
  1. Today
    Jun 15
    Foggy
    —
    —
    75°57°—
  2. Tuesday
    Jun 16
    Foggy
    —
    —
    73°54°-2°
  3. Wednesday
    Jun 17
    Clear
    —
    —
    87°63°+14°
  4. Thursday
    Jun 18
    Clear
    —
    —
    80°59°-7°
  5. Friday
    Jun 19
    Clear
    —
    —
    81°59°+1°
  6. Saturday
    Jun 20
    Mostly Clear
    —
    —
    75°57°-6°
  7. Sunday
    Jun 21
    Clear
    —
    —
    79°55°+4°
Union City, CA
Next 24 hours · Cool now
50°65°80°12a6a12p6pnow 58°high 75°low 54°
Union City, CA
Anemometer · 24h winds · from true
NESW
From · True
N
350° · backing 49°
Direction
N
350°
Sustained
3
mph
Gust
3
mph
Peak 24h
17
avg 8
Beaufort · 1 · LIGHT AIR
0
CALM
<1
1
LIGHT AIR
1–3
2
LIGHT BRZ
4–7
3
GENTLE BRZ
8–12
4
MOD BRZ
13–18
5
FRESH BRZ
19–24
6
STRONG BRZ
25–31
7
NEAR GALE
32–38
24h · sust vs gust · mph
avg 8 · pk 17 @ 4:00p
01020MPHB1B2B3B4B5-21h-18h-15h-12h-9h-6h-3h-24hNOWpk 174SUSTGUST
−24h−18h−12h−6hnow
A whisper of wind — leaves barely shift on the trees.
Union City, CA
Barometer · 24h pressure · mb
STORMRAINCHANGEFAIRDRY9901000101010201030
Pressure · mb
1012.1
+1.6 mb in 3h · rising · 29.89 inHg
Now
1012.1
mb
3h
+1.6
mb
12h
+2.2
mb
24h
+2.4
mb
Regime · CHANGE
STORM
RAIN
CHANGE
FAIR
DRY
24h · Pressure · mb
range 1009–1012
9951000STORM|RAIN10051010RAIN|CHG1015CHG|FAIR10201025FAIR|DRY1030-21h-18h-15h-12h-9h-6h-3h-24hNOW1012.11009.41012.1
−24h−18h−12h−6hnow
Pressure climbing through the change line — drier air pushing in.
Union City, CA
Air quality
50
AQI
Good
→0 in 6h

AQI 50 (Good), driven by PM2.5. AQI flat over the last 6 hours (within ±3 points). PM2.5 at 13.6 µg/m³ (AQI 59) with a 0.76 fine-to-coarse ratio and 3 mph wind — combustion smoke trapped in calm air, not road dust.

OK No precautions needed for the general population; unusually sensitive individuals may consider limiting prolonged outdoor exertion.

PM 2.5DRIVERModerate
13.6μg/m³
PM 10Good
18μg/m³
NO₂Good
14μg/m³
OzoneGood
41μg/m³
UV IndexLow
0.3

What's driving it

PM × Wind × Precip

PM2.5 at 13.6 µg/m³ (AQI 59) with a 0.76 fine-to-coarse ratio and 3 mph wind — combustion smoke trapped in calm air, not road dust.

PM2.5/PM10
0.76
Wind
calm
Recent rain
0h in last 6h
Pattern
stagnant smoke

Trends

Seven days of AQI and PM2.5.

Hourly air-quality data from the Copernicus Atmosphere Monitoring Service, charted across the past and next several days. Dashed lines mark the AQI breakpoints at 50 (Good → Moderate) and 100 (Moderate → Unhealthy for Sensitive Groups).

7-DAY AQI TREND50100MONTUEWEDTHUFRISATSUNMON7-DAY PM2.5 TREND · μg/m³300
Union City, CA
Sky cover · visibility · 24h
Cloud cover
100%
OVERCAST
100%0%−24h−18h−12h−6hnow
Visibility
24.9mi
UNLIMITED
60 mi0 mi−24h−18h−12h−6hnow
Earth · GOES-19 ABI
Full Disk · Visible · GeoColor
GOES-19 full disk Visible · GeoColor
True-color daytime, blue/IR sandwich at night
14:01 UTC · Union City, CA · NOAA NESDIS / STAR · up to 10848 px
Continental US · GOES-19 ABI
CONUS Sector · Visible · GeoColor
GOES-19 CONUS Visible · GeoColor
Daytime true-color, blue-light/IR sandwich at night
14:01 UTC · Union City, CA · NOAA NESDIS / STAR · 5-min cadence · up to 10000 px
Union City, CA
Satellite · infrared · animated
Union City, CA
Loading IR frames…
IR · cloud-top temp© RainViewer · Carto
Union City, CA
Almanac · Monday, June 15
A summer fog for fair, a winter fog for rain.
Civil dawn
5:16 AM
Sunrise
10:46 PM
Daylight
14h 45m
Sunset
1:31 PM
Civil dusk
9:03 PM
Planting note
Stake and prune tomato suckers. Watch for squash vine borers.
Union City, CA
The moon
New Moon
1% illuminated
Moonrise
5:56 AM
Moonset
8:51 PM
In sign
♋︎ Cancer
Union City, CA
Microseason
Jun 11–15

Summer solstice light stretched thin

weather
Jan 145% of the yearDec 31

Read this microseason across nine climate regions →

Union City at a glance

  • Today vs. normal: 19°F below the seasonal normal for this latitude
  • Last frost: April 2 (climatological average for this latitude)
  • Microseason: Jun 11–15
  • Planting window: Stake and prune tomato suckers. Watch for squash vine borers.

16-Day Forecast — Union City

  1. Mon74°56°1%
  2. Tue73°54°0%
  3. Wed87°63°0%
  4. Thu80°59°0%
  5. Fri81°59°0%
  6. Sat75°57°0%
  7. Sun79°55°0%
  8. Mon80°56°0%
  9. Tue85°58°0%
  10. Wed86°61°0%
  11. Thu81°58°0%
  12. Fri83°57°0%
  13. Sat81°59°0%
  14. Sun81°60°0%
  15. Mon84°61°0%
  16. Tue85°62°3%

Forecast data from Open-Meteo (CC BY 4.0).

Live wind & temperature near Union City

Right now in the garden

Peak growing season

As of June 15, the growing season is at its peak — frost is months away. Continue succession-planting beans and summer squash. Start fall brassicas (broccoli, cabbage, kale) from seed indoors for transplanting in late summer.

January 1–5: New year in coastal mist.January 6–10: Hills hold the winter cold.January 11–15: Light lengthens over wet earth.January 16–20: The green pulse quickens.January 21–25: Spring green spreads inland.January 26–31: Winter's grip releases.February 1–5: Fog lifts, flowers open.February 6–10: Blooms erupt across chaparral.February 11–15: Winter blooms at their peak.February 16–20: Rivers recede, flowers spread.February 21–25: Earth warms, flowers rush upslope.February 26–28: Spring advances on cool winds.March 1–5: Grass and trees bud and break.March 6–10: Insects wake and feed.March 11–15: Blossoms crown the hillsides.March 16–20: Monarch chrysalis emergence.March 21–25: Light overtakes dark at equinox.March 26–31: California poppy ablaze.April 1–5: Spring rain feeds the seedlings.April 6–10: Warblers flood the understory.April 11–15: Allen's hummingbirds in courtship dives.April 16–20: Coastal fog settles; sun breaks midday.April 21–25: Oak canopies full and green.April 26–30: Chaparral awakens after spring rains.May 1–5: Coastal wildflowers at their peak.May 6–10: Gray whales complete their migration north.May 11–15: Redwood coast in cool shade.May 16–20: Fog and sun in daily rhythm.May 21–25: Summer approaches; hills turn gold.May 26–31: Dry season begins; tule fog in valleys.June 1–5: Coastal fog thickens at dawn.June 6–10: California poppies fade as heat rises.June 11–15: Summer solstice light stretched thin.June 16–20: Bay laurel fragrance sweetens shade.June 21–25: Longest daylight, driest air.June 26–30: Fog banks mask the turning tide.July 1–5: Summer heat deepens across the valleys.July 6–10: Warm winds drive dryness inland.July 11–15: Pacific high settles in firmly.July 16–20: Young hawks take to the thermals.July 21–25: Peak fire season, peak heat.July 26–31: Chaparral poised for ignition.August 1–5: August begins in scorching stillness.August 6–10: Autumn's first cool breath arrives.August 11–15: Cool winds signal the turning year.August 16–20: Evening cicada chorus.August 21–25: Marine layer descent.August 26–31: Monarch staging begins.September 1–5: Fire season intensity.September 6–10: Dew on drying grasses.September 11–15: Raptor passage begins.September 16–20: Equinox descent.September 21–25: Ceanothus blooms again.September 26–30: Insects retreat below.October 1–5: Creeks begin to whisper.October 6–10: Santa Ana wind season.October 11–15: Wildflower anticipation.October 16–20: Chaparral embers glow.October 21–25: First atmospheric river looms.October 26–31: Rains return at last.November 1–5: Coast live oak leaves turn amber.November 6–10: California lilac blooms in winter light.November 11–15: First rain greens the chaparral.November 16–20: Coastal fog thickens as storms approach.November 21–25: Thanksgiving rains swell the valleys.November 26–30: Autumn's last breath yields to winter.December 1–5: December arrives, storms accelerate.December 6–10: Winter solstice season intensifies.December 11–15: Deep winter: rivers at flood stage.December 16–20: Winter salmon runs peak in northern rivers.December 21–25: Winter solstice: the sun turns.December 26–31: Year's end in wind and rain.🌱February 14 — First skunk-cabbage spathes thaw their way up☀️March 20 — Spring equinox — day and night balance🌸April 5 — Cherry blossoms peak in the parks🐦May 10 — Warbler migration peaks along the coast✨May 25 — First fireflies scout the meadows at dusk🌞June 21 — Summer solstice — longest day🦗July 25 — Peak cicada chorus in the afternoons🌊August 18 — Warmest sea-surface temperatures of the year🍂September 22 — Autumn equinox — the slow turn❄️October 25 — First widespread frost in the suburbs🍁November 10 — Peak leaf color across the Hudson Valley🌙December 21 — Winter solstice — longest night

Microseason · June 11–15

Summer solstice light stretched thin

The sun's arc peaks; evening light lingers until past 8:30pm across the coast and Bay Area.

Day 166 of 365 · Wedge 33 of 72

The solar year drawn as a wheel of 72 five-day windows. Each wedge is one microseason; the four colored arcs mark winter, spring, summer, and autumn; the small icons sit at notable phenological events. The crimson pointer creeps clockwise as the year turns.

Planting calendar

MonthPlantHarvest
January——
February——
March——
Aprillettuce, peas, spinach, radishes—
Maylettuce, peas, spinach, radishes, tomatoes, peppers, beans, squashlettuce, peas, radishes
Junetomatoes, peppers, beans, squashlettuce, peas, radishes
Julytomatoes, peppers, beans, squashtomatoes, beans, summer squash
August—tomatoes, beans, summer squash
Septemberfall brassicas, garlic (overwinter), carrotstomatoes, beans, summer squash
Octoberfall brassicas, garlic (overwinter), carrotswinter squash, tomatoes (last)
November——
December——

A year in weather

Union City peaks at about 68°F in August and bottoms near 51°F in December; February brings the heaviest rain (3.2 inches) and July the least (0.0 inches).

MonthMean tempPrecipRainy days
January51°3.0″6
February53°3.2″7
March56°2.5″6
April58°1.2″4
May62°0.5″2
June65°0.2″0
July67°0.0″0
August68°0.0″0
September67°0.1″0
October63°0.7″2
November55°1.6″4
December51°3.0″7

Regional context

In Union City, NOAA NCEI 1991-2020 normals put January near 51°F and July near 67°F — a 17°F seasonal arc — with about 15.9 inches of precipitation over 37 rainy or snowy days.

Union City's moisture rides winter storm tracks: February brings 3.2 inches over 6.8 wet days, while July sees only 0.0 inches across 0.0 days in the dry warm season. It is a winter-storm rhythm Union City shares with places like Hayward, CA, Fairview, CA and Fremont, CA.

With a coldest-month mean of 51°F, Union City stays mostly frost-free and grows year-round. The August peak near 68°F is Union City's real limit, pushing cool-season vegetables to spring and fall. Across Union City, elevation and tree cover drive a 4-7°F spread in Union City's overnight lows.

Similar climates: Hayward, CA, Fairview, CA, Fremont, CA, Newark, CA, Cherryland, CA.

Frequently asked

When does it freeze in Union City?
Union City's last spring frost lands near mid-April, and in Union City the first fall frost follows around mid-November.
What is the rainy season in Union City?
Rainfall in Union City peaks in February near 3.2 inches, out of about 16 inches annually.
What is the warmest month in Union City?
The warmest stretch in Union City comes in August, around 68°F on average.
What is the coldest month in Union City?
On average December is the chilliest month in Union City, about 51°F.
When can I start a vegetable garden in Union City?
Frost-hardy sowings begin at mid-April in Union City; warm-season starts follow two weeks on.
How many rainy days does Union City get?
Expect roughly 37 wet days a year in Union City.
What hardiness zone is Union City?
Union City sits in the USDA zone set by December lows near 51°F; the USDA ZIP tool gives the band.
What is the 10-day forecast for Union City?
Union City's extended outlook — daily high and low temperatures and precipitation chances for each upcoming day — is in the daily forecast above.
Will it rain this week in Union City?
See this week's day-by-day rain chances for Union City in the daily forecast above, and the next 24 hours in the hourly chart.
What is the weather like right now in Union City?
Current conditions for Union City and the next 24 hours — temperature, precipitation chance, and wind by the hour — are in the hourly forecast chart above.
How often is the Union City forecast updated?
The Union City forecast on this page is built from Open-Meteo weather-model data and refreshes regularly through the day.
When are sunrise and sunset in Union City?
Day length in Union City peaks around the June solstice — earliest sunrise and latest sunset — and is shortest near the December solstice.
How accurate is the weather forecast for Union City?
The next few days in Union City's forecast are the most reliable; accuracy declines beyond about a week as weather-model uncertainty grows.

Climate

Union City's hot-summer Mediterranean climate in California pairs 51°F Januarys with 67°F Julys, 16°F apart across the seasons.

Yearly precipitation in Union City totals around 16 inches, spread over about 37 days of rain or snow.

The 16°F gap between Union City's summer and winter, at 37.6°N, shapes Union City's frost calendar.

All cities in California →

Oakland, CA weather →

ZIP codes in Union City

  • 94552
  • 94587

Climate normals from the Open-Meteo Climate API. Köppen approximation from NOAA NCEI U.S. Climate Regions. See methodology for data sources, editorial rules, and corrections. Maintainer: Brian Tighe.