Weather StoryAlmanac, microseasons, and the day's weather story.

South San Francisco, California Weather

Summer heat deepens across the valleys. Day 15 of summer. Read this microseason across nine climate regions →

South San Francisco weather forecast — hour by hour, 7-day outlook, NOAA radar

South San Francisco, CA
Sunday, July 5 at 10:04 AM
61
°
Mostly Clear
Feels like
58°
Humidity
79%
Wind
11 mph
Sunrise
10:54 PM
Sunset
1:34 PM
South San Francisco, CA
Hour by hour · 24h
24-Hour ForecastSouth San Francisco, CA: 24-hour forecast. Temperatures range from 54 to 64 degrees Fahrenheit.
L 54°H 64°
South San Francisco, CA
7-day forecast
  1. Today
    Jul 5
    Foggy
    —
    —
    64°53°—
  2. Monday
    Jul 6
    Foggy
    —
    —
    63°54°-1°
  3. Tuesday
    Jul 7
    Foggy
    —
    —
    65°54°+2°
  4. Wednesday
    Jul 8
    Overcast
    —
    —
    70°56°+5°
  5. Thursday
    Jul 9
    Overcast
    —
    —
    66°58°-4°
  6. Friday
    Jul 10
    Overcast
    —
    —
    70°56°+4°
  7. Saturday
    Jul 11
    Overcast
    —
    —
    72°57°+2°
South San Francisco, CA
Next 24 hours · Cool now
50°58°66°6a12p6p12anow 61°high 64°low 54°
South San Francisco, CA
Anemometer · 24h winds · from true
NESW
From · True
W
264° · backing 31°
Direction
W
264°
Sustained
11
mph
Gust
14
mph
Peak 24h
21
avg 11
Beaufort · 3 · GENTLE BRZ
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 11 · pk 21 @ 5:00p
0102030MPHB1B2B3B4B5B6-21h-18h-15h-12h-9h-6h-3h-24hNOWpk 238SUSTGUST
−24h−18h−12h−6hnow
Light breeze backing 31° from the w.
South San Francisco, CA
Barometer · 24h pressure · mb
STORMRAINCHANGEFAIRDRY9901000101010201030
Pressure · mb
1015.4
+0.3 mb in 3h · steady · 29.98 inHg
Now
1015.4
mb
3h
+0.3
mb
12h
+0.1
mb
24h
-0.5
mb
Regime · FAIR
STORM
RAIN
CHANGE
FAIR
DRY
24h · Pressure · mb
range 1014–1016
1010RAIN|CHG1015CHG|FAIR10201025FAIR|DRY-21h-18h-15h-12h-9h-6h-3h-24hNOW1016.11014.01015.4
−24h−18h−12h−6hnow
Fair, steady air — a quiet anticyclone holds the sky.
South San Francisco, CA
Air quality
26
AQI
Good
→-1 in 6h

AQI 26 (Good), driven by PM2.5. AQI flat over the last 6 hours (within ±3 points). PM2.5 at 4.5 µg/m³ (AQI 25), ratio 0.66 with 11 mph wind — characteristic of long-range haze transport rather than a local source.

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

PM 2.5DRIVERGood
4.5μg/m³
PM 10Good
7μg/m³
NO₂Good
3μg/m³
OzoneGood
51μg/m³
UV IndexModerate
2.9

What's driving it

PM × Wind × Precip

PM2.5 at 4.5 µg/m³ (AQI 25), ratio 0.66 with 11 mph wind — characteristic of long-range haze transport rather than a local source.

PM2.5/PM10
0.66
Wind
breezy
Recent rain
0h in last 6h
Pattern
transport

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 TREND50100SUNMONTUEWEDTHUFRISATSUN7-DAY PM2.5 TREND · μg/m³300
South San Francisco, CA
Sky cover · visibility · 24h
Cloud cover
41%
MOSTLY CLEAR
100%0%−24h−18h−12h−6hnow
Visibility
32.0mi
UNLIMITED
40 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
17:04 UTC · South San Francisco, 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
17:04 UTC · South San Francisco, CA · NOAA NESDIS / STAR · 5-min cadence · up to 10000 px
South San Francisco, CA
Satellite · infrared · animated
South San Francisco, CA
Loading IR frames…
IR · cloud-top temp© RainViewer · Carto
South San Francisco, CA
Almanac · Sunday, July 5
If the first of July be rainy weather, 'twill rain more or less for four weeks together.
Civil dawn
5:24 AM
Sunrise
10:54 PM
Daylight
14h 40m
Sunset
1:34 PM
Civil dusk
9:06 PM
Planting note
Harvest early potatoes. Begin drying onions on the surface.
South San Francisco, CA
The moon
Waning Gibbous
71% illuminated
Moonrise
11:29 PM
Moonset
11:28 AM
In sign
♓︎ Pisces
South San Francisco, CA
Microseason
Jul 1–5

Summer heat deepens across the valleys

weather
Jan 151% of the yearDec 31

Read this microseason across nine climate regions →

South San Francisco at a glance

  • Today vs. normal: 13°F below the seasonal normal for this latitude
  • Last frost: April 2 (climatological average for this latitude)
  • Microseason: Jul 1–5
  • Planting window: Harvest early potatoes. Begin drying onions on the surface.

ZIP code: 94080

16-Day Forecast — South San Francisco

  1. Sun64°53°6%
  2. Mon63°54°2%
  3. Tue65°54°1%
  4. Wed70°56°0%
  5. Thu66°58°0%
  6. Fri70°56°0%
  7. Sat72°57°0%
  8. Sun77°57°1%
  9. Mon79°60°3%
  10. Tue80°61°6%
  11. Wed66°60°0%
  12. Thu88°63°1%
  13. Fri88°64°0%
  14. Sat80°65°0%
  15. Sun74°61°3%
  16. Mon69°58°6%

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

Live wind & temperature near South San Francisco

Right now in the garden

Peak growing season

As of July 5, 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 · July 1–5

Summer heat deepens across the valleys

Inland temperatures exceed 95°F regularly; fire danger reaches moderate to high across most of the region.

Day 186 of 365 · Wedge 37 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

The year in South San Francisco tops out in September (~63°F) and dips lowest in January (~52°F), with December wettest at 4.8 inches and July driest at 0.0 inches.

MonthMean tempPrecipRainy days
January52°4.4″8
February54°4.4″8
March56°3.1″7
April56°1.6″4
May58°0.7″2
June60°0.2″1
July60°0.0″0
August62°0.1″0
September63°0.1″0
October62°0.9″2
November57°2.6″5
December53°4.8″8

Regional context

By the nearest station's NOAA NCEI 1991-2020 normals, South San Francisco sees 52°F Januarys and 60°F Julys, a 8°F range, plus around 22.9 inches of precipitation across 45 days.

South San Francisco's moisture rides winter storm tracks: December brings 4.8 inches over 8.0 wet days, while July sees only 0.0 inches across 0.0 days in the dry warm season. That cool-season-wet pattern aligns South San Francisco with places like San Bruno, CA, Colma, CA and Brisbane, CA.

Freezes are uncommon in South San Francisco, where the coldest month averages 52°F; cool-season crops grow fall through spring. Summer heat in September (about 63°F) is the binding constraint, not cold. South San Francisco's coastal lots stay 4-7°F milder overnight than South San Francisco's inland parcels.

Similar climates: San Bruno, CA, Colma, CA, Brisbane, CA, Daly City, CA, Millbrae, CA.

Frequently asked

When does it freeze in South San Francisco?
Frost typically leaves South San Francisco by mid-April and returns to South San Francisco near mid-November.
What is the rainy season in South San Francisco?
South San Francisco sees its heaviest rain in December (around 4.8 inches), part of roughly 23 inches a year.
What is the warmest month in South San Francisco?
On average September tops the year in South San Francisco at about 63°F.
What is the coldest month in South San Francisco?
The coldest stretch in South San Francisco falls in January, around 52°F on average.
When can I start a vegetable garden in South San Francisco?
In South San Francisco, sow peas and hardy greens around mid-April; South San Francisco's tomatoes and peppers wait two weeks more.
How many rainy days does South San Francisco get?
South San Francisco averages about 45 days with measurable rain or snow each year.
What hardiness zone is South San Francisco?
With January around 52°F, South San Francisco's zone reflects that minimum — the USDA ZIP map confirms South San Francisco's band.
What is the 10-day forecast for South San Francisco?
South San Francisco'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 South San Francisco?
See this week's day-by-day rain chances for South San Francisco in the daily forecast above, and the next 24 hours in the hourly chart.
What is the weather like right now in South San Francisco?
Current conditions for South San Francisco and the next 24 hours — temperature, precipitation chance, and wind by the hour — are in the hourly forecast chart above.
How often is the South San Francisco forecast updated?
The South San Francisco forecast on this page is built from Open-Meteo weather-model data and refreshes regularly through the day.
When are sunrise and sunset in South San Francisco?
Today's sunrise and sunset times for South San Francisco are in the Almanac section above, along with civil dawn, civil dusk, and day length. Day length is longest near the summer solstice and shortest near the winter solstice.
How accurate is the weather forecast for South San Francisco?
The next few days in South San Francisco's forecast are the most reliable; accuracy declines beyond about a week as weather-model uncertainty grows.

Climate

Set in a hot-summer Mediterranean zone, South San Francisco, California swings from 52°F in the heart of winter to 60°F at midsummer — a 8°F arc.

Rain and snow bring South San Francisco roughly 23 inches a year across approximately 45 measurable-precipitation days.

South San Francisco sits at 37.7°N; that 8°F seasonal swing frames planting windows and frost dates across South San Francisco.

All cities in California →

San Francisco, CA weather →

ZIP codes in South San Francisco

  • 94080
  • 94083

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.