San Juan, Texas Weather
Fireflies pulse through the magnolias. Day 77 of spring. Read this microseason across nine climate regions →
San Juan weather forecast — hour by hour, 7-day outlook, NOAA radar
- TodayJun 3Overcast19%—93°78°—
- ThursdayJun 4Heavy Showers25%1.2″90°76°-3°
- FridayJun 5Overcast53%—92°77°+2°
- SaturdayJun 6Showers26%—95°78°+3°
- SundayJun 7Overcast13%—97°78°+2°
- MondayJun 8Overcast11%—96°79°-1°
- TuesdayJun 9Overcast16%—91°76°-5°
AQI 21 (Good), driven by PM2.5. AQI flat over the last 6 hours (within ±4 points).
OK No precautions needed for the general population; unusually sensitive individuals may consider limiting prolonged outdoor exertion.
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).
A summer fog for fair, a winter fog for rain.
- Moonrise
- 4:25 AM
- Moonset
- 3:11 PM
- In sign
- ♑︎ Capricorn
Fireflies pulse through the magnolias
San Juan at a glance
- Today vs. normal: 7°F below the seasonal normal for this latitude
- Last frost: January 23 (climatological average for this latitude)
- Microseason: Jun 1–5
- Planting window: Harvest spring lettuce before it bolts. Sow heat-tolerant greens.
Right now in the garden
Peak growing season
As of June 4, 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.
SPC Convective Outlook
Storm Prediction Center — San Juan
SPC has placed San Juan in the General Thunderstorms category for severe thunderstorms today.
- TODAYTSTMGeneral Thunderstorms
- TOMORROWTSTMGeneral Thunderstorms
- DAY 3TSTMGeneral Thunderstorms
Thunderstorms possible. Not severe, but capable of producing lightning and brief heavy rain.
Source: NOAA / NWS Storm Prediction Center categorical convective outlook. Outlooks are re-issued multiple times per day; this page reflects the most recent SPC polygons covering the city’s coordinates.
Planting calendar
| Month | Plant | Harvest |
|---|---|---|
| January | — | — |
| February | lettuce, peas, spinach, radishes | — |
| March | lettuce, peas, spinach, radishes, tomatoes, peppers, beans, squash | — |
| April | tomatoes, peppers, beans, squash | — |
| May | tomatoes, peppers, beans, squash | lettuce, peas, radishes |
| June | — | lettuce, peas, radishes |
| July | — | tomatoes, beans, summer squash |
| August | — | tomatoes, beans, summer squash |
| September | — | tomatoes, beans, summer squash |
| October | fall brassicas, garlic (overwinter), carrots | winter squash, tomatoes (last) |
| November | fall brassicas, garlic (overwinter), carrots | — |
| December | — | — |
A year in weather
San Juan's warmest month is August (~88°F mean) and its coldest is January (~60°F). Rainfall peaks in September (3.8 inches) and bottoms out in December (0.6 inches).
| Month | Mean temp | Precip | Rainy days |
|---|---|---|---|
| January | 60° | 0.7″ | 2 |
| February | 65° | 0.6″ | 1 |
| March | 70° | 1.0″ | 2 |
| April | 76° | 1.4″ | 2 |
| May | 82° | 1.4″ | 2 |
| June | 86° | 3.0″ | 3 |
| July | 87° | 1.6″ | 2 |
| August | 88° | 1.4″ | 3 |
| September | 84° | 3.8″ | 5 |
| October | 78° | 2.0″ | 3 |
| November | 68° | 1.1″ | 2 |
| December | 62° | 0.6″ | 2 |
Regional context
San Juan sits within a humid subtropical climate region — a cohort that shares similar temperature ranges, seasonal patterns, and growing conditions across nearby cities.
Similar climates: Houston, TX, Dallas, TX, San Antonio, TX, Austin, TX, Fort Worth, TX.
Frequently asked
- When does it freeze in San Juan?
- San Juan's last spring frost typically falls around mid-February, and the first fall frost arrives around mid-December.
- What is the rainy season in San Juan?
- September is the wettest month with about 3.8 inches of rain on average; the city receives roughly 19 inches annually.
- What is the warmest month in San Juan?
- August is typically warmest, averaging about 88°F.
- What is the coldest month in San Juan?
- January is typically coldest, averaging about 60°F.
- When can I start a vegetable garden in San Juan?
- Cool-season crops (peas, lettuce) can be sown around the last spring frost (mid-February); warm-season crops (tomatoes, peppers) wait until 1–2 weeks after.
- How many rainy days does San Juan get?
- San Juan averages about 29 rainy days per year.
- What hardiness zone is San Juan?
- San Juan's USDA hardiness zone is determined by its lowest average winter temperature; check the USDA's online lookup with the city ZIP for the current zone designation.
Climate
San Juan, Texas sits in a humid subtropical climate zone. January means hover near 60°F while July averages 87°F — a 27°F seasonal swing.
Across the year, San Juan receives about 19 inches of precipitation spread over roughly 29 rainy days.
The rhythm of the year is set by latitude (26.2°N), proximity to large water bodies, and elevation — all of which shape what grows here, when frost is likely, and what the weather story looks like day to day.