San Juan is rarely comfortable to be outside at midday. It comes closest in mid February, and even then it is too hot. For sun, aim for November to July.
When to go five ratings · thirty-six ten-day sections · click a cell to read it
For sun, go from November to July. It peaks in mid March, at 80. Avoid mid September to early October for this: it falls to 39, mostly because it is too hot. The clearest skies come in March, when the sky is typically 53% covered at midday (partly cloudy).
San Juan never quite rates Good for being outside. It comes closest in mid February, at 47, mostly because it is too hot. The weakest stretch is from late May to November, when it drops to 0, mostly because it is too hot.
Walking is not what San Juan is for: the Active outdoors rating tops out at 6, mostly because it is too warm.
The year, measured
The average temperature in San Juan over the whole year is 27°C. September is the hottest month, with highs of about 31°C; January is the coldest, with lows of about 23°C. San Juan has no sharply defined rainy season: the chance of rain on a given day runs from 19% in March, the driest month, to 26% in November, the wettest. Winds in San Juan are highest in July, averaging 4.1 m/s (15 km/h), and lightest in October, at 2.4 m/s (9 km/h). The prevailing wind is from the E. The clearest skies in San Juan come in September, when the sky is typically 51% covered; November is the cloudiest month, at 55%.
Month by month San Juan climate by month: average temperatures year round · click a month to read it
| Month | High | Low | Feels like | Chance of rain | Cloud | Wind | Being outside | Sun | Walking |
|---|---|---|---|---|---|---|---|---|---|
| January | 28°C | 23°C | 29°C | 20% | 52% | 3.2 m/s | 36 | 79 | 3 |
| February | 28°C | 24°C | 28°C | 23% | 53% | 3.6 m/s | 44 | 75 | 5 |
| March | 28°C | 23°C | 28°C | 19% | 52% | 3.7 m/s | 40 | 77 | 4 |
| April | 28°C | 24°C | 29°C | 24% | 55% | 3.5 m/s | 29 | 76 | 2 |
| May | 29°C | 25°C | 31°C | 24% | 53% | 3.5 m/s | 10 | 66 | 0 |
| June | 30°C | 26°C | 32°C | 23% | 52% | 3.9 m/s | 4 | 59 | 0 |
| July | 30°C | 27°C | 32°C | 25% | 53% | 4.1 m/s | 2 | 58 | 0 |
| August | 31°C | 27°C | 33°C | 26% | 52% | 3.7 m/s | 1 | 50 | 0 |
| September | 31°C | 27°C | 34°C | 20% | 51% | 2.9 m/s | 1 | 42 | 0 |
| October | 31°C | 26°C | 34°C | 24% | 53% | 2.4 m/s | 1 | 47 | 0 |
| November | 30°C | 25°C | 32°C | 26% | 55% | 2.5 m/s | 4 | 63 | 0 |
| December | 29°C | 24°C | 30°C | 25% | 53% | 3.1 m/s | 20 | 73 | 1 |
High and low are the warmest and coolest of four readings a day — midnight, 6am, noon and 6pm — so a true overnight low can sit a degree or two under them. Chance of rain, cloud and wind are the day’s average; feels-like and the three ratings (each out of 100: Good from 55, Ideal from 80) are read at midday.
Seasons, and the year in short San Juan weather by season
Year round, San Juan has days of about 28°C at their warmest in February, its coolest month, and 31°C in September, its warmest; the coolest hours of the day run from 23°C to 27°C through the year, and the average temperature over the year is 27°C around the clock. Rain is most likely around November and least likely around March. Every figure here is a decade of observations blended into one representative year, so it reads as what this date is usually like, not a forecast for one particular day.
San Juan weather in winterDecember to February
Winter in San Juan has typical daily highs of about 28°C and lows of about 24°C, with a 23% chance of rain on a given day.
San Juan weather in springMarch to May
Spring in San Juan has typical daily highs of about 28°C and lows of about 24°C, with a 22% chance of rain on a given day.
San Juan weather in summerJune to August
Summer in San Juan has typical daily highs of about 30°C and lows of about 27°C, with a 24% chance of rain on a given day.
San Juan weather in autumnSeptember to November
Autumn in San Juan has typical daily highs of about 30°C and lows of about 26°C, with a 23% chance of rain on a given day.
When is the rainy season in San Juan?
San Juan has no sharply defined rainy season: the chance of rain on a given day runs from 19% in March, the driest month, to 26% in November, the wettest.
What time of year is San Juan windiest?
Winds in San Juan are highest in July, averaging 4.1 m/s (15 km/h), and lightest in October, at 2.4 m/s (9 km/h). The prevailing wind is from the E.
What is the average temperature in San Juan year round?
The average temperature in San Juan over the whole year is 27°C. September is the hottest month, with highs of about 31°C; January is the coldest, with lows of about 23°C.
Where to go instead in early August, the weakest time here for being outside
How this is worked out
Every figure is a decade of weather-station observations blended into one typical year, in ten-day sections. The ratings, the chart and the feels-like column are read at midday local solar time. Being outside is the Easy outdoors rating, Sun is Sunbathing and Walking is Active outdoors, each out of 100: Good from 55, Ideal from 80. They describe what a time of year is usually like here, not a forecast. The dotted links open the map at that time of year; set its time of day to midday to see these numbers.