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

San Juan, Puerto Rico Weather

August opens — storms become routine. Day 43 of summer. Read this microseason across nine climate regions →

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

San Juan, PR
Sunday, August 2 at 11:01 AM
89
°
Partly Cloudy
Feels like
97°
Humidity
54%
Wind
9 mph
Sunrise
2:02 AM
Sunset
2:58 PM
San Juan, PR
Hour by hour · 24h
24-Hour ForecastSan Juan, PR: 24-hour forecast. Temperatures range from 79 to 92 degrees Fahrenheit with a 63% chance of precipitation at 2 PM.
L 79°H 92°
San Juan, PR
7-day forecast
  1. Today
    Aug 2
    Drizzle
    63%
    0.03″
    92°80°—
  2. Monday
    Aug 3
    Overcast
    17%
    —
    93°79°+1°
  3. Tuesday
    Aug 4
    Heavy Drizzle
    94%
    0.02″
    89°78°-4°
  4. Wednesday
    Aug 5
    Thunderstorm
    92%
    0.04″
    89°77°0°
  5. Thursday
    Aug 6
    Thunderstorm
    79%
    0.01″
    90°78°+1°
  6. Friday
    Aug 7
    Drizzle
    59%
    0.05″
    90°77°0°
  7. Saturday
    Aug 8
    Light Drizzle
    47%
    0.05″
    92°79°+2°
San Juan, PR
Next 24 hours · Warm now
HOT 90°76°86°96°12p6p12a6anow 89°high 92°low 79°PRECIP %
San Juan, PR
Anemometer · 24h winds · from true
NESW
From · True
E
100° · veering 13°
Direction
E
100°
Sustained
9
mph
Gust
23
mph
Peak 24h
28
avg 7 mph
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 7 mph · pk 28 mph @ 2:00p
0102030MPHB1B2B3B4B5B6-21h-18h-15h-12h-9h-6h-3h-24hNOWpk 278SUSTGUST
−24h−18h−12h−6hnow
Light breeze veering 13° from the e.
San Juan, PR
Barometer · 24h pressure · mb
STORMRAINCHANGEFAIRDRY9901000101010201030
Pressure · mb
1015.2
+0.1 mb in 3h · steady · 29.98 inHg
Now
1015.2
mb
3h
+0.1
mb
12h
+0.7
mb
24h
+1.0
mb
Regime · FAIR
STORM
RAIN
CHANGE
FAIR
DRY
24h · Pressure · mb
range 1013–1016
9951000STORM|RAIN10051010RAIN|CHG1015CHG|FAIR10201025FAIR|DRY1030-21h-18h-15h-12h-9h-6h-3h-24hNOW1015.51012.71015.2
Fair, steady air — a quiet anticyclone holds the sky.
San Juan, PR
Air quality
27
AQI
Good
→+2 in 6h

AQI 27 (Good), driven by PM2.5. AQI flat over the last 6 hours (within ±3 points). PM2.5 at 8.6 µg/m³ (AQI 48), ratio 0.57 with 9 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
8.6μg/m³
PM 10Good
15μg/m³
NO₂Good
0μg/m³
OzoneGood
39μg/m³
UV IndexVery high
7.2

What's driving it

PM × Wind × Precip

PM2.5 at 8.6 µg/m³ (AQI 48), ratio 0.57 with 9 mph wind — characteristic of long-range haze transport rather than a local source.

PM2.5/PM10
0.57
Wind
light
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/m³310
San Juan, PR
Sky cover · visibility · 24h
Cloud cover
79%
MOSTLY CLOUDY
100%0%−24h−18h−12h−6hnow
Visibility
90.1mi
UNLIMITED
92 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
15:01 UTC · San Juan, PR · 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
15:01 UTC · San Juan, PR · NOAA NESDIS / STAR · 5-min cadence · up to 10000 px
San Juan, PR
Satellite · infrared · animated
San Juan, PR
Loading IR frames…
IR · cloud-top temp© RainViewer · Carto
San Juan, PR
Almanac · Sunday, August 2
Red sky at night, sailor's delight.
Civil dawn
5:40 AM
Sunrise
2:02 AM
Daylight
12h 56m
Sunset
2:58 PM
Civil dusk
7:23 PM
Planting note
Sow fall peas. Start kale and collard seedlings for fall.
San Juan, PR
The moon
Waning Gibbous
84% illuminated
Moonrise
9:01 PM
Moonset
9:23 AM
In sign
♓︎ Pisces
San Juan, PR
Microseason
Aug 1–5

August opens — storms become routine

plant
Jan 159% of the yearDec 31

Read this microseason across nine climate regions →

San Juan at a glance

  • Today vs. normal: 5°F above the seasonal normal for this latitude
  • Last frost: December 7 (climatological average for this latitude)
  • Microseason: Aug 1–5
  • Planting window: Sow fall peas. Start kale and collard seedlings for fall.

ZIP codes: 00901, 00906, 00907, 00909, 00911, 00912, 00913, 00915 +9 more

16-Day Forecast — San Juan

  1. Sun92°80°63%
  2. Mon93°79°17%
  3. Tue89°78°94%
  4. Wed89°77°92%
  5. Thu90°78°79%
  6. Fri90°77°59%
  7. Sat92°79°47%
  8. Sun90°79°66%
  9. Mon83°78°77%
  10. Tue91°80°71%
  11. Wed91°80°66%
  12. Thu91°78°68%
  13. Fri92°80°55%
  14. Sat93°81°43%
  15. Sun90°77°50%
  16. Mon91°76°48%

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

Live wind & temperature near San Juan

Right now in the garden

Peak growing season

As of August 2, 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.

Sun & seasons in San Juan

San Juan sits in San Juan County, where the year’s longest day runs 13h 14m of daylight and its shortest just 11h 1m — a swing of +2h 13m between the June and December solstices.

Aguadilla, the state’s largest city, lies about 72 miles to the W. The nearest town San Juan tracks is Carolina, roughly 5 miles to the E.

Air quality in San Juan’s county has trended cleaner since 2020; its cleanest year on record was 2021 (median AQI 7). See the full air-quality history for San Juan.

January 1–5: The year turns in trade winds.January 6–10: Reefs reflect clear winter light.January 11–15: Mangrove buds swell with green.January 16–20: Hibiscus opens in January sun.January 21–25: Early-blooming aster brings gold.January 26–31: Last cold breath, green rising.February 1–5: Plumeria and ceiba crown the canopy.February 6–10: Coral spawn timing aligns with moon.February 11–15: Morning dew lingers on new leaves.February 16–20: Trade-wind rhythm softens slightly.February 21–25: Humidity breaks the dry season spell.February 26–28: Mist rises where rain falls inland.March 1–5: Green thickens in every direction.March 6–10: Hidden creatures awaken in dampness.March 11–15: Fruiting cycles deepen as rains persist.March 16–20: Wings emerge from green.March 21–25: Light holds the horizon.March 26–31: Coral blooms begin.April 1–5: Thunder rolls across the sea.April 6–10: Migrants pour southward.April 11–15: Green deepens in all things.April 16–20: Rain paints the sky.April 21–25: Green shoots rise from the shore.April 26–30: Heat breaks the last restraint.May 1–5: Lei Day—flowers crown the islands.May 6–10: Rain falls on greening grain.May 11–15: Green life breaks upward.May 16–20: Flowers spill across the islands.May 21–25: Summer arrives in thunder.May 26–31: Frogs sing the summer in.June 1–5: First trades stir the ceiba canopy.June 6–10: Afternoon showers claim the ritual.June 11–15: Easterly waves thread the Atlantic.June 16–20: Reef polyps synchronize in moonlight.June 21–25: The sun reaches its zenith turn.June 26–30: Lightning bugs dance above the flooded lowlands.July 1–5: Midyear heat — the wet season grip.July 6–10: Warm breeze across the mangrove maze.July 11–15: Storm surge begins its rhythm.July 16–20: Juvenile raptors test the thermals.July 21–25: The earth releases its breath — humidity peaks.July 26–31: Fruits swell in the tropical canopy.August 1–5: August opens — storms become routine.August 6–10: Autumn whispers in the trade wind shift.August 11–15: Cool winds find their path again.August 16–20: Cicadas hum through the heat.August 21–25: Trade winds gather strength.August 26–31: Hurricane season intensifies.September 1–5: Peak storm season dawns.September 6–10: Wet-season rains peak.September 11–15: Mid-season storm lull.September 16–20: Equinox approaches.September 21–25: Storm intensity ebbs slightly.September 26–30: Late-season storms persist.October 1–5: Easterly waves train across the basin.October 6–10: Hurricane season's second peak.October 11–15: Seasonal wind shift emerges.October 16–20: Atlantic storms retreat.October 21–25: Trade winds solidify.October 26–31: Dry season's arrival.November 1–5: Last storms clear the horizon.November 6–10: Dry season takes hold.November 11–15: Migratory arrivals from the north.November 16–20: The emerald deepens.November 21–25: Dust veil settles.November 26–30: Harvest calm descends.December 1–5: Deep dry season opens.December 6–10: Winter trades blow strong.December 11–15: Solstice approaches in green silence.December 16–20: The sun turns again.December 21–25: Solstice—renewal in stillness.December 26–31: Year's end in tropical stillness.🌱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 · August 1–5

August opens — storms become routine

Great rains fall without warning. Flash floods recede in hours. Mangrove prop roots strain. Corals bleach if water temp exceeds 30.5°C. Named storm threat real.

Day 214 of 365 · Wedge 43 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——
Februarylettuce, peas, spinach, radishes—
Marchlettuce, peas, spinach, radishes, tomatoes, peppers, beans, squash—
Apriltomatoes, peppers, beans, squash—
Maytomatoes, peppers, beans, squashlettuce, peas, radishes
June—lettuce, peas, radishes
July—tomatoes, beans, summer squash
August—tomatoes, beans, summer squash
September—tomatoes, beans, summer squash
Octoberfall brassicas, garlic (overwinter), carrotswinter squash, tomatoes (last)
Novemberfall brassicas, garlic (overwinter), carrots—
December——

A year in weather

San Juan's warmest month is August (~82°F mean) and its coldest is January (~76°F). Rainfall peaks in October (4.5 inches) and bottoms out in February (1.2 inches).

MonthMean tempPrecipRainy days
January76°1.6″28
February76°1.2″26
March77°1.6″26
April78°2.6″27
May80°3.9″30
June81°2.5″28
July82°2.4″30
August82°3.5″30
September81°4.1″29
October80°4.5″31
November78°3.6″29
December77°2.6″30

Regional context

Per NOAA NCEI 1991-2020 normals, San Juan runs from a 76°F January mean to 82°F in July, a 6°F seasonal spread, with near 34.2 inches of precipitation across about 343 wet days.

Summer convection drives San Juan's precipitation: October logs 4.5 inches on 30.7 rainy days, against February's 1.2 inches on 25.5 — warm-season storms carry San Juan's moisture. That summer-storm rhythm groups San Juan with places like Caño Martin Peña, PR, Guaynabo, PR and Trujillo Alto, PR.

Hard freezes are rare in San Juan: the coldest month averages 76°F, so San Juan's growing window runs most of the year. August is the hottest stretch near 82°F, pushing cool-season crops to the milder shoulder months. Within San Juan, low or inland lots lose 3-5°F overnight versus San Juan's coastal ground.

Similar climates: Caño Martin Peña, PR, Guaynabo, PR, Trujillo Alto, PR, Carolina, PR, Cataño, PR.

Naturalist notes

May brings the peak flowering period for flamboyant trees, their orange-red blooms creating canopies of color across the city.

Trade winds carry migrating warblers northward during late April and early May, as these small birds follow ancient flyways toward North American breeding grounds.

Frequently asked

When does it freeze in San Juan?
Frost typically leaves San Juan by mid-February and returns to San Juan near mid-December.
What is the rainy season in San Juan?
Rainfall in San Juan peaks in October near 4.5 inches, out of about 34 inches annually.
What is the warmest month in San Juan?
The warmest stretch in San Juan comes in August, around 82°F on average.
What is the coldest month in San Juan?
On average January is the chilliest month in San Juan, about 76°F.
When can I start a vegetable garden in San Juan?
Frost-hardy sowings begin at mid-February in San Juan; warm-season starts follow two weeks on.
How many rainy days does San Juan get?
San Juan averages about 343 days with measurable rain or snow each year.
What hardiness zone is San Juan?
San Juan's hardiness zone tracks its winter low; with January near 76°F, check the USDA ZIP map for the exact zone.
What is the 10-day forecast for San Juan?
San Juan'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 San Juan?
See this week's day-by-day rain chances for San Juan in the daily forecast above, and the next 24 hours in the hourly chart.
What is the weather like right now in San Juan?
Current conditions for San Juan and the next 24 hours — temperature, precipitation chance, and wind by the hour — are in the hourly forecast chart above.
How often is the San Juan forecast updated?
The San Juan forecast on this page is built from Open-Meteo weather-model data and refreshes regularly through the day.
When are sunrise and sunset in San Juan?
Today's sunrise and sunset times for San Juan 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 San Juan?
The next few days in San Juan's forecast are the most reliable; accuracy declines beyond about a week as weather-model uncertainty grows.

Climate

San Juan, Puerto Rico occupies a varied zone, with January means near 76°F and July around 82°F — a 6°F swing.

Across the year, San Juan collects about 34 inches of precipitation over roughly 343 days with measurable rain or snow.

Latitude 18.4°N gives San Juan its 6°F swing, and with it the rhythm of San Juan's growing season.

All cities in Puerto Rico →

ZIP codes in San Juan

  • 00918
  • 00913
  • 00912
  • 00911
  • 00917
  • 00915
  • 00926
  • 00927
  • 00924
  • 00925
  • 00923
  • 00920
  • 00921
  • 00906
  • 00907
  • 00901
  • 00909
  • 00969
  • 00908
  • 00910
  • 00919
  • 00922
  • 00928
  • 00929
  • 00931
  • 00935
  • 00936
  • 00937
  • 00939
  • 00940
  • 00955
  • 00975

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.