San Juan weather in January
In January, San Juan sees average daytime highs of 21°C and overnight lows near 14°C, with 104 mm of rain across 13.3 wet days and about 11.5 hours of daylight. It is the 12th-warmest and 9th-wettest month of the year here.
Day-to-day highs hold fairly steady near 21°C through the month. The sky is clear or mostly clear about 27% of the time in January, and the air most often feels comfortable.
Daylight stretches from about 11 h 24 min at the start of January to 11 h 36 min by month's end. Set against the rest of the year, January is San Juan's 2nd-clearest and 1st-windiest month. For the whole year in context, see San Juan's year-round climate.
- Daytime high
- 21°
- 12th warmest
- Overnight low
- 14°
- 1st coldest
- Rainfall
- 104 mm
- 13.3 wet days
- Daylight
- 11 h 30 min
- 6:01 AM – 5:30 PM
- Cloud cover
- 57%
- 2nd clearest
- Wind
- 8 km/h
- 1st windiest
- Solar energy
- 4.77 kWh/m²
- Travel score
- 6.0
- out of 10
San Juan is district in Tibás canton, San José province, Costa Rica.
- Density
- 7,421/km²
- people per km²
Air quality: WHO Ambient Air Quality Database. Density & description: Wikidata (CC0), GeoNames.
Temperature in January
Day-to-day highs hold fairly steady near 21°C through the month.
A typical January day in San Juan reaches about 21°C in the afternoon and slips back to 14°C overnight — a 7°C spread between the day's warmth and the night's chill. On most days the high lands between 19°C and 23°C. Set against its neighbours, January runs on par with December and on par with February.
| 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18 | 19 | 20 | 21 | 22 | 23 | 24 | 25 | 26 | 27 | 28 | 29 | 30 | 31 | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Avg high (°C) | 21 | 21 | 21 | 21 | 21 | 21 | 21 | 21 | 21 | 21 | 21 | 21 | 21 | 21 | 21 | 21 | 21 | 21 | 21 | 21 | 21 | 21 | 21 | 21 | 21 | 21 | 21 | 21 | 21 | 21 | 21 |
| Avg low (°C) | 14 | 14 | 14 | 14 | 14 | 14 | 14 | 14 | 14 | 14 | 14 | 14 | 14 | 14 | 14 | 14 | 14 | 14 | 14 | 14 | 14 | 14 | 14 | 14 | 14 | 14 | 14 | 14 | 14 | 14 | 14 |
| Avg high (°C) | Avg low (°C) | |
|---|---|---|
| 1 | 21 | 14 |
| 2 | 21 | 14 |
| 3 | 21 | 14 |
| 4 | 21 | 14 |
| 5 | 21 | 14 |
| 6 | 21 | 14 |
| 7 | 21 | 14 |
| 8 | 21 | 14 |
| 9 | 21 | 14 |
| 10 | 21 | 14 |
| 11 | 21 | 14 |
| 12 | 21 | 14 |
| 13 | 21 | 14 |
| 14 | 21 | 14 |
| 15 | 21 | 14 |
| 16 | 21 | 14 |
| 17 | 21 | 14 |
| 18 | 21 | 14 |
| 19 | 21 | 14 |
| 20 | 21 | 14 |
| 21 | 21 | 14 |
| 22 | 21 | 14 |
| 23 | 21 | 14 |
| 24 | 21 | 14 |
| 25 | 21 | 14 |
| 26 | 21 | 14 |
| 27 | 21 | 14 |
| 28 | 21 | 14 |
| 29 | 21 | 14 |
| 30 | 21 | 14 |
| 31 | 21 | 14 |
San Juan weather by month
How January compares with the rest of the year at a glance. January is the 12th-warmest and 9th-wettest month here — the current month is highlighted below.
| Month | High / Low (°C) | Rainfall (mm) | Wet days | Daylight (hours) | Travel score |
|---|---|---|---|---|---|
| Jan | 21° / 14° | 104 | 13.3 | 11.5 | 6.0 |
| Feb | 22° / 14° | 68 | 11.9 | 11.7 | 6.2 |
| Mar | 23° / 14° | 65 | 13.9 | 11.9 | 6.1 |
| Apr | 23° / 15° | 102 | 18 | 12.2 | 5.3 |
| May | 23° / 16° | 357 | 27.8 | 12.4 | 3.8 |
| Jun | 23° / 16° | 385 | 28.8 | 12.6 | 3.5 |
| Jul | 23° / 16° | 293 | 28.2 | 12.5 | 3.7 |
| Aug | 23° / 16° | 345 | 28.5 | 12.3 | 3.7 |
| Sep | 23° / 16° | 391 | 29.1 | 12.1 | 3.5 |
| Oct | 22° / 16° | 430 | 30.1 | 11.8 | 3.4 |
| Nov | 22° / 15° | 312 | 25.5 | 11.5 | 4.0 |
| Dec | 21° / 15° | 170 | 17.8 | 11.4 | 5.3 |
Cloud cover in January
The sky is clear or mostly clear about 27% of the time in January.
Beyond those clear spells, partly cloudy skies cover about 27% of January, with mostly cloudy or overcast conditions the remaining 45%. Skies tend to open up as the month goes on.
| 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18 | 19 | 20 | 21 | 22 | 23 | 24 | 25 | 26 | 27 | 28 | 29 | 30 | 31 | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Clearer (%) | 50 | 50 | 49 | 50 | 51 | 51 | 51 | 52 | 52 | 51 | 52 | 52 | 53 | 53 | 54 | 54 | 55 | 55 | 56 | 56 | 57 | 57 | 57 | 58 | 58 | 59 | 59 | 60 | 61 | 61 | 62 |
| Cloudier (%) | 50 | 50 | 51 | 50 | 49 | 49 | 49 | 48 | 48 | 49 | 48 | 48 | 47 | 47 | 46 | 46 | 45 | 45 | 44 | 44 | 43 | 43 | 43 | 42 | 42 | 41 | 41 | 40 | 39 | 39 | 38 |
| Clearer (%) | Cloudier (%) | |
|---|---|---|
| 1 | 50 | 50 |
| 2 | 50 | 50 |
| 3 | 49 | 51 |
| 4 | 50 | 50 |
| 5 | 51 | 49 |
| 6 | 51 | 49 |
| 7 | 51 | 49 |
| 8 | 52 | 48 |
| 9 | 52 | 48 |
| 10 | 51 | 49 |
| 11 | 52 | 48 |
| 12 | 52 | 48 |
| 13 | 53 | 47 |
| 14 | 53 | 47 |
| 15 | 54 | 46 |
| 16 | 54 | 46 |
| 17 | 55 | 45 |
| 18 | 55 | 45 |
| 19 | 56 | 44 |
| 20 | 56 | 44 |
| 21 | 57 | 43 |
| 22 | 57 | 43 |
| 23 | 57 | 43 |
| 24 | 58 | 42 |
| 25 | 58 | 42 |
| 26 | 59 | 41 |
| 27 | 59 | 41 |
| 28 | 60 | 40 |
| 29 | 61 | 39 |
| 30 | 61 | 39 |
| 31 | 62 | 38 |
Chance of precipitation in January
San Juan gets around 104 mm of rain over 13.3 wet days in January. The line is the day-by-day chance of measurable precipitation.
Day to day, the chance of measurable rain averages around 43% and peaks near 51% on the wettest days. The odds ease toward the end of the month.
| 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18 | 19 | 20 | 21 | 22 | 23 | 24 | 25 | 26 | 27 | 28 | 29 | 30 | 31 | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Rain chance (%) | 51 | 50 | 50 | 49 | 49 | 48 | 48 | 47 | 47 | 46 | 46 | 45 | 45 | 44 | 43 | 43 | 42 | 42 | 41 | 41 | 41 | 40 | 39 | 39 | 39 | 38 | 38 | 38 | 38 | 38 | 38 |
| Rain chance (%) | |
|---|---|
| 1 | 51 |
| 2 | 50 |
| 3 | 50 |
| 4 | 49 |
| 5 | 49 |
| 6 | 48 |
| 7 | 48 |
| 8 | 47 |
| 9 | 47 |
| 10 | 46 |
| 11 | 46 |
| 12 | 45 |
| 13 | 45 |
| 14 | 44 |
| 15 | 43 |
| 16 | 43 |
| 17 | 42 |
| 18 | 42 |
| 19 | 41 |
| 20 | 41 |
| 21 | 41 |
| 22 | 40 |
| 23 | 39 |
| 24 | 39 |
| 25 | 39 |
| 26 | 38 |
| 27 | 38 |
| 28 | 38 |
| 29 | 38 |
| 30 | 38 |
| 31 | 38 |
Humidity in January
Most of January feels comfortable — the stacked bands show each day's mix of comfort levels, read off the dew point.
By dew point, January lands in the comfortable band about 71% of days. It rarely turns muggy — the humid and sticky bands barely register.
| 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18 | 19 | 20 | 21 | 22 | 23 | 24 | 25 | 26 | 27 | 28 | 29 | 30 | 31 | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Dry (%) | 7 | 8 | 8 | 9 | 10 | 10 | 11 | 12 | 13 | 14 | 16 | 17 | 18 | 19 | 20 | 21 | 22 | 22 | 23 | 23 | 24 | 24 | 24 | 24 | 25 | 25 | 26 | 26 | 27 | 27 | 27 |
| Comfortable (%) | 74 | 74 | 76 | 76 | 76 | 77 | 76 | 76 | 76 | 75 | 74 | 73 | 73 | 72 | 71 | 70 | 70 | 70 | 69 | 69 | 68 | 68 | 68 | 68 | 67 | 67 | 66 | 66 | 65 | 65 | 65 |
| Humid (%) | 19 | 18 | 16 | 15 | 14 | 13 | 13 | 12 | 11 | 11 | 10 | 10 | 9 | 9 | 9 | 9 | 8 | 8 | 8 | 8 | 8 | 8 | 8 | 8 | 8 | 8 | 8 | 8 | 8 | 8 | 8 |
| Dry (%) | Comfortable (%) | Humid (%) | |
|---|---|---|---|
| 1 | 7 | 74 | 19 |
| 2 | 8 | 74 | 18 |
| 3 | 8 | 76 | 16 |
| 4 | 9 | 76 | 15 |
| 5 | 10 | 76 | 14 |
| 6 | 10 | 77 | 13 |
| 7 | 11 | 76 | 13 |
| 8 | 12 | 76 | 12 |
| 9 | 13 | 76 | 11 |
| 10 | 14 | 75 | 11 |
| 11 | 16 | 74 | 10 |
| 12 | 17 | 73 | 10 |
| 13 | 18 | 73 | 9 |
| 14 | 19 | 72 | 9 |
| 15 | 20 | 71 | 9 |
| 16 | 21 | 70 | 9 |
| 17 | 22 | 70 | 8 |
| 18 | 22 | 70 | 8 |
| 19 | 23 | 69 | 8 |
| 20 | 23 | 69 | 8 |
| 21 | 24 | 68 | 8 |
| 22 | 24 | 68 | 8 |
| 23 | 24 | 68 | 8 |
| 24 | 24 | 68 | 8 |
| 25 | 25 | 67 | 8 |
| 26 | 25 | 67 | 8 |
| 27 | 26 | 66 | 8 |
| 28 | 26 | 66 | 8 |
| 29 | 27 | 65 | 8 |
| 30 | 27 | 65 | 8 |
| 31 | 27 | 65 | 8 |
Wind in January
Winds average 8 km/h in January, the windiest month of the year.
Across January, daily wind ranges from about 8 km/h on the calmest days to 8 km/h at its breeziest. It stays fairly steady from day to day.
| 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18 | 19 | 20 | 21 | 22 | 23 | 24 | 25 | 26 | 27 | 28 | 29 | 30 | 31 | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Wind speed (km/h) | 8 | 8 | 8 | 8 | 8 | 8 | 8 | 8 | 8 | 8 | 8 | 8 | 8 | 8 | 8 | 8 | 8 | 8 | 8 | 8 | 8 | 8 | 8 | 8 | 8 | 8 | 8 | 8 | 8 | 8 | 8 |
| Feels | calm | calm | calm | calm | calm | calm | calm | calm | calm | calm | calm | calm | calm | calm | calm | calm | calm | calm | calm | calm | calm | calm | calm | calm | calm | calm | calm | calm | calm | calm | calm |
| Wind speed (km/h) | Feels | |
|---|---|---|
| 1 | 8 | calm |
| 2 | 8 | calm |
| 3 | 8 | calm |
| 4 | 8 | calm |
| 5 | 8 | calm |
| 6 | 8 | calm |
| 7 | 8 | calm |
| 8 | 8 | calm |
| 9 | 8 | calm |
| 10 | 8 | calm |
| 11 | 8 | calm |
| 12 | 8 | calm |
| 13 | 8 | calm |
| 14 | 8 | calm |
| 15 | 8 | calm |
| 16 | 8 | calm |
| 17 | 8 | calm |
| 18 | 8 | calm |
| 19 | 8 | calm |
| 20 | 8 | calm |
| 21 | 8 | calm |
| 22 | 8 | calm |
| 23 | 8 | calm |
| 24 | 8 | calm |
| 25 | 8 | calm |
| 26 | 8 | calm |
| 27 | 8 | calm |
| 28 | 8 | calm |
| 29 | 8 | calm |
| 30 | 8 | calm |
| 31 | 8 | calm |
Sunrise & sunset in January
Daylight runs from about 11 h 24 min at the start of January to 11 h 36 min by month's end. The lit band spans sunrise to sunset each day.
Days grow by about 12 minutes over January. Sunrise moves from 5:57 AM to 6:03 AM, and sunset from 5:22 PM to 5:36 PM.
| 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18 | 19 | 20 | 21 | 22 | 23 | 24 | 25 | 26 | 27 | 28 | 29 | 30 | 31 | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Daylight (h) | 11.4 | 11.4 | 11.4 | 11.4 | 11.4 | 11.4 | 11.4 | 11.4 | 11.4 | 11.5 | 11.5 | 11.5 | 11.5 | 11.5 | 11.5 | 11.5 | 11.5 | 11.5 | 11.5 | 11.5 | 11.5 | 11.5 | 11.5 | 11.5 | 11.5 | 11.5 | 11.5 | 11.5 | 11.5 | 11.6 | 11.6 |
| Sunrise (AM) | 5:57 | 5:57 | 5:57 | 5:58 | 5:58 | 5:59 | 5:59 | 5:59 | 5:59 | 6:00 | 6:00 | 6:00 | 6:01 | 6:01 | 6:01 | 6:01 | 6:02 | 6:02 | 6:02 | 6:02 | 6:02 | 6:02 | 6:02 | 6:03 | 6:03 | 6:03 | 6:03 | 6:03 | 6:03 | 6:03 | 6:03 |
| Sunset (PM) | 5:22 | 5:23 | 5:23 | 5:24 | 5:24 | 5:25 | 5:25 | 5:26 | 5:26 | 5:27 | 5:27 | 5:28 | 5:28 | 5:29 | 5:29 | 5:30 | 5:30 | 5:31 | 5:31 | 5:32 | 5:32 | 5:33 | 5:33 | 5:34 | 5:34 | 5:34 | 5:35 | 5:35 | 5:36 | 5:36 | 5:36 |
| Daylight (h) | Sunrise (AM) | Sunset (PM) | |
|---|---|---|---|
| 1 | 11.4 | 5:57 | 5:22 |
| 2 | 11.4 | 5:57 | 5:23 |
| 3 | 11.4 | 5:57 | 5:23 |
| 4 | 11.4 | 5:58 | 5:24 |
| 5 | 11.4 | 5:58 | 5:24 |
| 6 | 11.4 | 5:59 | 5:25 |
| 7 | 11.4 | 5:59 | 5:25 |
| 8 | 11.4 | 5:59 | 5:26 |
| 9 | 11.4 | 5:59 | 5:26 |
| 10 | 11.5 | 6:00 | 5:27 |
| 11 | 11.5 | 6:00 | 5:27 |
| 12 | 11.5 | 6:00 | 5:28 |
| 13 | 11.5 | 6:01 | 5:28 |
| 14 | 11.5 | 6:01 | 5:29 |
| 15 | 11.5 | 6:01 | 5:29 |
| 16 | 11.5 | 6:01 | 5:30 |
| 17 | 11.5 | 6:02 | 5:30 |
| 18 | 11.5 | 6:02 | 5:31 |
| 19 | 11.5 | 6:02 | 5:31 |
| 20 | 11.5 | 6:02 | 5:32 |
| 21 | 11.5 | 6:02 | 5:32 |
| 22 | 11.5 | 6:02 | 5:33 |
| 23 | 11.5 | 6:02 | 5:33 |
| 24 | 11.5 | 6:03 | 5:34 |
| 25 | 11.5 | 6:03 | 5:34 |
| 26 | 11.5 | 6:03 | 5:34 |
| 27 | 11.5 | 6:03 | 5:35 |
| 28 | 11.5 | 6:03 | 5:35 |
| 29 | 11.5 | 6:03 | 5:36 |
| 30 | 11.6 | 6:03 | 5:36 |
| 31 | 11.6 | 6:03 | 5:36 |
Solar energy in January
Average shortwave solar energy reaching the ground each day in January, about 4.77 kWh/m².
For context, solar energy here swings from a low near 3.58 kWh/m² to a high of 5.78 kWh/m² in March across the year — January's 4.77 kWh/m² falls in the middle.
| 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18 | 19 | 20 | 21 | 22 | 23 | 24 | 25 | 26 | 27 | 28 | 29 | 30 | 31 | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Solar energy (kWh/m²) | 4.5 | 4.5 | 4.5 | 4.5 | 4.5 | 4.5 | 4.6 | 4.6 | 4.6 | 4.6 | 4.7 | 4.7 | 4.7 | 4.7 | 4.7 | 4.8 | 4.8 | 4.8 | 4.8 | 4.9 | 4.9 | 4.9 | 5.0 | 5.0 | 5.0 | 5.0 | 5.0 | 5.1 | 5.1 | 5.1 | 5.1 |
| Level | Bright | Bright | Bright | Bright | Bright | Bright | Bright | Bright | Bright | Bright | Bright | Bright | Bright | Bright | Bright | Bright | Bright | Bright | Bright | Bright | Bright | Bright | Bright | Bright | Bright | Bright | Bright | Bright | Bright | Bright | Bright |
| Solar energy (kWh/m²) | Level | |
|---|---|---|
| 1 | 4.5 | Bright |
| 2 | 4.5 | Bright |
| 3 | 4.5 | Bright |
| 4 | 4.5 | Bright |
| 5 | 4.5 | Bright |
| 6 | 4.5 | Bright |
| 7 | 4.6 | Bright |
| 8 | 4.6 | Bright |
| 9 | 4.6 | Bright |
| 10 | 4.6 | Bright |
| 11 | 4.7 | Bright |
| 12 | 4.7 | Bright |
| 13 | 4.7 | Bright |
| 14 | 4.7 | Bright |
| 15 | 4.7 | Bright |
| 16 | 4.8 | Bright |
| 17 | 4.8 | Bright |
| 18 | 4.8 | Bright |
| 19 | 4.8 | Bright |
| 20 | 4.9 | Bright |
| 21 | 4.9 | Bright |
| 22 | 4.9 | Bright |
| 23 | 5.0 | Bright |
| 24 | 5.0 | Bright |
| 25 | 5.0 | Bright |
| 26 | 5.0 | Bright |
| 27 | 5.0 | Bright |
| 28 | 5.1 | Bright |
| 29 | 5.1 | Bright |
| 30 | 5.1 | Bright |
| 31 | 5.1 | Bright |
Is January a good time to visit San Juan?
Our two travel scores rate January for general sightseeing and for beach or pool weather — 0 (poor) to 10 (ideal).
January is a reasonable time to visit San Juan for sightseeing.
What to pack for San Juan in January
From January's temperature range, rain chance, sun and wind — what's worth putting in the bag.
In January, San Juan sees daytime highs around 21°C and nights near 14°C. Worth packing: rain gear and sun protection. About 13 days see rain.
Sea temperature near San Juan in January
The nearest coast averages about 29°C in January — the other half of the beach question. The full-year curve and swim-comfort zones are below.
The sea at the nearest coast (about 61 km away) is warmest in April at about 29°C and coldest in November near 28°C.
The water stays above 20°C all year — warm enough for a swim any month.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Sea temperature (°C) | 29 | 29 | 29 | 29 | 29 | 29 | 29 | 29 | 29 | 28 | 28 | 28 |
| Comfort | Tropical | Tropical | Tropical | Tropical | Tropical | Tropical | Tropical | Tropical | Tropical | Tropical | Warm | Tropical |
| Sea temperature (°C) | Comfort | |
|---|---|---|
| Jan | 29 | Tropical |
| Feb | 29 | Tropical |
| Mar | 29 | Tropical |
| Apr | 29 | Tropical |
| May | 29 | Tropical |
| Jun | 29 | Tropical |
| Jul | 29 | Tropical |
| Aug | 29 | Tropical |
| Sep | 29 | Tropical |
| Oct | 28 | Tropical |
| Nov | 28 | Warm |
| Dec | 28 | Tropical |
UV index in San Juan in January
Clear-sky midday UV in January peaks around 12 (very high — sun protection essential). The full-year curve, shaded by WHO exposure level, is below.
Under clear skies, the midday UV index in San Juan peaks around March 19 at about 15 (extreme) — sunscreen, a hat and midday shade are essential. It bottoms out near December 16 at about 10 (extreme).
The index reaches 3 or more — the level where the WHO recommends sun protection — every month of the year.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| UV index (midday) | 12 | 14 | 15 | 14 | 13 | 13 | 13 | 13 | 13 | 12 | 12 | 10 |
| Level | Extreme | Extreme | Extreme | Extreme | Extreme | Extreme | Extreme | Extreme | Extreme | Extreme | Extreme | Extreme |
| UV index (midday) | Level | |
|---|---|---|
| Jan | 12 | Extreme |
| Feb | 14 | Extreme |
| Mar | 15 | Extreme |
| Apr | 14 | Extreme |
| May | 13 | Extreme |
| Jun | 13 | Extreme |
| Jul | 13 | Extreme |
| Aug | 13 | Extreme |
| Sep | 13 | Extreme |
| Oct | 12 | Extreme |
| Nov | 12 | Extreme |
| Dec | 10 | Extreme |
Air quality in San Juan in January
Average fine-particle pollution (PM2.5) through the year — so you can see where January falls, not just the annual average.
Air quality in San Juan is worst in May — around 19 µg/m³ PM2.5 (moderate), about 2.1× the cleanest month (January, 9 µg/m³).
Modeled monthly averages (CAMS reanalysis, 2015–2024).
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| PM2.5 (µg/m³) | 9 | 10 | 11 | 17 | 19 | 17 | 18 | 17 | 16 | 14 | 12 | 10 |
| Level | Good | Good | Good | Moderate | Moderate | Moderate | Moderate | Moderate | Moderate | Moderate | Good | Good |
| PM2.5 (µg/m³) | Level | |
|---|---|---|
| Jan | 9 | Good |
| Feb | 10 | Good |
| Mar | 11 | Good |
| Apr | 17 | Moderate |
| May | 19 | Moderate |
| Jun | 17 | Moderate |
| Jul | 18 | Moderate |
| Aug | 17 | Moderate |
| Sep | 16 | Moderate |
| Oct | 14 | Moderate |
| Nov | 12 | Good |
| Dec | 10 | Good |
Where is San Juan?
San Juan sits at 10.0°N, 84.1°W, 1,114 m above sea level, in Costa Rica. The nearest listed city is Colima, 1.0 km away.
Topography around San Juan
How much the land rises and falls, and what covers it, within 3, 16 and 80 km of San Juan.
Within 3 km, the terrain around San Juan has only modest variations in elevation — a maximum elevation change of 220 m around an average of 1,157 m above sea level; within 16 km, very significant variations in elevation — a maximum elevation change of 1,764 m; within 80 km, extreme variations in elevation — a maximum elevation change of 3,674 m.
The land around San Juan is covered by artificial surfaces (65%) and trees (27%) within 3 km, trees (58%) and artificial surfaces (27%) within 16 km, and trees (71%) within 80 km.
Costa Rica travel facts
- Travel advisory
- Level 2
- Exercise Increased Caution
- Power plugs
- Type A / B
- 120 V · 60 Hz
- Prices
- ≈ 59% of US
- price level, 2025
- GDP per capita
- $19,970
- 2025
- Happiness
- 7.4 / 10
- World Happiness, 2025
- Safe drinking water
- 81%
- of population, 2024
- Homicide rate
- 17.7
- per 100k, 2023
- Road deaths
- 14.8
- per 100k/yr, 2019
- Income group
- High
- World Bank
- English
- Moderate
- EF EPI 516
- Religion
Sources: World Bank, US State Department, World Happiness Report, WHO/UNICEF, EF EPI, CIA World Factbook.
Data sources
Temperature, precipitation, cloud, humidity, wind and solar figures are a 1991–2020 climatology for San Juan (9.9619°, -84.0788°, elevation 1,114 m), computed from hourly ERA5 reanalysis — contains modified Copernicus Climate Change Service information. Sun figures are astronomical calculations, not observations. City data © GeoNames, CC BY 4.0. Map outlines from Natural Earth (public domain); interactive map © Google. Sea temperatures are the NOAA OISST v2.1 1991–2020 monthly climatology (public domain), sampled at the nearest ocean point. UV index is derived from CAMS (Copernicus Atmosphere Monitoring Service) clear-sky UV data — contains modified Copernicus Atmosphere Monitoring Service information. Monthly air-quality (PM2.5) seasonality is from the CAMS EAC4 reanalysis (Copernicus Atmosphere Monitoring Service), scaled to the WHO annual mean where available. Topography is sampled from the Copernicus DEM GLO-90 elevation model (© ESA/Airbus) and ESA WorldCover 2021 land cover (CC BY 4.0).