Weather in San Isidro, Puerto Rico
Flowers spill across the islands. Day 59 of spring. Read this microseason across nine climate regions →
- TodayMay 17Light Drizzle78%87°77°
- MondayMay 18Light Drizzle65%87°75°
- TuesdayMay 19Light Drizzle42%87°76°
- WednesdayMay 20Drizzle74%81°74°
- ThursdayMay 21Light Drizzle56%87°74°
- FridayMay 22Light Drizzle71%86°74°
- SaturdayMay 23Drizzle66%86°76°
- PM 2.5
- 9.0 μg/m³
- PM 10
- 16.9 μg/m³
- NO₂
- 0.8 μg/m³
- Ozone
- 46.0 μg/m³
- UV Index
- 0.0 Low
When the dew is on the grass, rain will never come to pass.
- Moonrise
- 10:11 AM
- Moonset
- —
- In sign
- ♊︎ Gemini
Flowers spill across the islands
San Isidro at a glance
- Today vs. normal: 14°F below the seasonal normal for this latitude
- Last frost: December 7 (climatological average for this latitude)
- Microseason: 28 of 72, May 16–20
- Planting window: Direct sow okra, melons, and southern peas. Thin carrot rows.
Right now in the garden
Peak growing season
As of May 17, 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.
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 Isidro's warmest month is August (~85°F mean) and its coldest is January (~69°F). Rainfall peaks in September (8.2 inches) and bottoms out in February (2.0 inches).
| Month | Mean temp | Precip | Rainy days |
|---|---|---|---|
| January | 69° | 2.1″ | 7 |
| February | 71° | 2.0″ | 7 |
| March | 73° | 2.2″ | 7 |
| April | 77° | 3.3″ | 11 |
| May | 80° | 4.8″ | 16 |
| June | 83° | 7.9″ | 25 |
| July | 84° | 5.8″ | 19 |
| August | 85° | 6.9″ | 23 |
| September | 83° | 8.2″ | 25 |
| October | 81° | 7.9″ | 25 |
| November | 76° | 3.3″ | 11 |
| December | 72° | 2.5″ | 8 |
Regional context
San Isidro sits within a varied climate region — a cohort that shares similar temperature ranges, seasonal patterns, and growing conditions across nearby cities.
Similar climates: San Juan, PR, Aguadilla, PR, Bayamón, PR, Carolina, PR, Arecibo, PR.
Frequently asked
- When does it freeze in San Isidro?
- San Isidro'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 Isidro?
- September is the wettest month with about 8.2 inches of rain on average; the city receives roughly 57 inches annually.
- What is the warmest month in San Isidro?
- August is typically warmest, averaging about 85°F.
- What is the coldest month in San Isidro?
- January is typically coldest, averaging about 69°F.
- When can I start a vegetable garden in San Isidro?
- 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 Isidro get?
- San Isidro averages about 184 rainy days per year.
- What hardiness zone is San Isidro?
- San Isidro'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 Isidro, Puerto Rico sits in a varied climate zone. January means hover near 69°F while July averages 84°F — a 15°F seasonal swing.
Across the year, San Isidro receives about 57 inches of precipitation spread over roughly 184 rainy days.
The rhythm of the year is set by latitude (18.4°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.