January weather forecast
San Juan, PR

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An old fort building and a view of the stunning San Juan city, Puerto Rico
An old fort building and a view of the stunning San Juan city, Puerto Rico

Weather in January

In San Juan, a tendency towards a cooler climate makes January distinctive. The average high sits slightly below the annual norm at 79.9°F (26.6°C), while the sea temperature sees a slight dip to 79.7°F (26.5°C). Despite less daylight and sunshine hours, clear skies remain prevalent with cloud cover at a minimal 32%. Winds maintain an average of 9.8mph (15.8km/h), yet gusts can reach up to 14mph (22.5km/h). The relatively tranquil state of the weather during the month ushers in a peaceful start to the year.

Temperature

Temperatures reach their minimum during January and March, recording an average high-temperature of 79.9°F (26.6°C).

Humidity

In San Juan, the average relative humidity in January is 77%.

Rainfall

In January, the rain falls for 11.5 days. Throughout January, 0.83" (21mm) of precipitation is accumulated. In San Juan, Puerto Rico, during the entire year, the rain falls for 159.9 days and collects up to 12.01" (305mm) of precipitation.

Ocean temperature

In San Juan, in January, the average water temperature is 79.7°F (26.5°C).
Note: With water temperature from 77°F (25°C) to 84.2°F (29°C), all water activities are comfortable and delightful, devoid of discomfort even for lengthened periods.

Daylight

In January, the average length of the day is 11h and 10min.
On the first day of the month, sunrise is at 6:56 am and sunset at 5:59 pm. On the last day of January, sunrise is at 6:58 am and sunset at 6:17 pm AST.

Sunshine

In San Juan, the average sunshine in January is 8.8h.

UV index

January through March and December, with an average maximum UV index of 6, are months with the lowest UV index. A UV Index of 6 to 7 symbolizes a high threat to health from unsafe exposure to UV radiation for the ordinary person.
Note: The maximum daily UV index of 6 in January interprets into the following recommendations:
Stay clear of intense sun exposure. Solar protection is of utmost significance. Remember that UV radiation from the Sun is strongest between 10 a.m. and 4 p.m. Make an effort to limit direct sun exposure during this time. In bright sunlight, prioritize sunglasses that grant protection from UVA and UVB radiation. Attention! UV radiation is markedly stronger with water and sand reflections.

Frequently asked questions

What month is the coldest?

January and March are identified as the coldest months, with an average high-temperature of 79.9°F (26.6°C).

What is the average January temperature in San Juan?

In San Juan, in January, the average high-temperature is 79.9°F (26.6°C), and the average low-temperature is 74.7°F (23.7°C).

What is the average humidity in January?

In San Juan, the average relative humidity in January is 77%.

How many days does it rain in January?

In San Juan, in January, it is raining for 11.5 days, with typically 0.83" (21mm) of accumulated precipitation.

How warm is the water in January?

In San Juan, in January, the average water temperature is 79.7°F (26.5°C). Water temperature between 77°F (25°C) and 84.2°F (29°C) is regarded as very warm and enjoyable by all. With these temperatures, water activities are pleasurable, without feeling uncomfortable for prolonged periods.

How many hours of daylight does San Juan have in January?

The average day length in January is 11h and 10min.

When is the sunrise / sunset in January?

In January, on the first day of the month, sunrise is at 6:56 am and sunset at 5:59 pm. On the last day of the month, sunrise is at 6:58 am and sunset at 6:17 pm AST.

How many hours of sunshine does San Juan have in January?

The average sunshine duration in January in San Juan is 8.8h.

What is the month with the lowest UV index?

The months with the lowest UV index are January through March and December, with an average maximum UV index of 6.

What is the UV index reading in January?

In January, the average daily maximum UV index is 6. A UV Index estimate of 6 to 7 represents a high hazard to health from exposure to the Sun's UV radiation.

Average temperature in January
San Juan, PR

Average temperature in January - San Juan, PR
  • Average high temperature in January: 79.9°F

The warmest month (with the highest average high temperature) is August (85.1°F).
The months with the lowest average high temperature are January and March (79.9°F).

  • Average low temperature in January: 74.7°F

The months with the highest average low temperature are August, September and October (79.2°F).
The coldest month (with the lowest average low temperature) is March (73.9°F).

Average pressure in January
San Juan, PR

Average pressure in January - San Juan, PR
  • Average pressure in January: 30.02"Hg

The months with the highest atmospheric pressure are January and February (30.02"Hg).
The month with the lowest atmospheric pressure is October (29.9"Hg).

Average wind speed in January
San Juan, PR

Average wind speed in January - San Juan, PR
  • Average wind speed in January: 9.8mph

The windiest month (with the highest average wind speed) is July (10.7mph).
The calmest month (with the lowest average wind speed) is October (7.4mph).

Average humidity in January
San Juan, PR

Average humidity in January - San Juan, PR
  • Average humidity in January: 77%

The months with the highest relative humidity are May, June and July (79%).
The months with the lowest relative humidity are February and March (76%).

Average rainfall in January
San Juan, PR

Average rainfall in January - San Juan, PR
  • Average rainfall in January: 0.83"

The wettest month (with the highest rainfall) is November (1.57").
The driest month (with the least rainfall) is April (0.55").

Average rainfall days in January
San Juan, PR

Average rainfall days in January - San Juan, PR
  • Average rainfall days in January: 11.5 days

The month with the highest number of rainy days is November (16.1 days).
The month with the least rainy days is June (10.3 days).

Average sea temperature in January
San Juan, PR

Average sea temperature in January - San Juan, PR
  • Average sea temperature in January: 79.7°F

The best month for swimming (with the highest average sea temperature) is September (84.9°F).
The coldest month (with the lowest average sea temperature) is February (78.9°F).

Average daylight in January /
Average sunshine in January
San Juan, PR

Average daylight in January / Average sunshine in January - San Juan, PR
  • Average daylight in January: 11h and 1min

The month with the longest days is June (Average daylight: 13h and 12min).
The month with the shortest days is December (Average daylight: 11h and 0min).

  • Average sunshine in January: 8h and 5min

The month with the most sunshine is June (Average sunshine: 10h and 54min).
The month with the least sunshine is December (Average sunshine: 6h and 36min).

Average sunshine days in January
San Juan, PR

Average sunshine days in January - San Juan, PR
  • Average sunshine days in January: 11.1 days

The month with the most sunshine days is June (13.7 days).
The month with the least sunshine days is November (9.4 days).

Average UV index in January
San Juan, PR

Average UV index in January - San Juan, PR
  • Average UV index in January: 6

The months with the highest UV index are April, May, June, July, August, September, October and November (UV index 7).
The months with the lowest UV index are January, February, March and December (UV index 6).

Average cloud cover in January
San Juan, PR

Average cloud cover in January - San Juan, PR
  • Average cloud cover in January: 32

The month with the most cloud cover is December (Cloud cover 35).
The month with the least cloud cover is September (Cloud cover 26).

Average visibility in January
San Juan, PR

Average visibility in January - San Juan, PR
  • Average visibility in January: 6mi

The months with the highest visibility are January, February, March, April, May, June, July, August, September, October, November and December (6mi).
The months with the lowest visibility are January, February, March, April, May, June, July, August, September, October, November and December (6mi).

San Juan, Puerto Rico, USA

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