January weather - Winter 2025

Weather in January
Frequently asked questions
Average temperature in January
Average pressure in January
Average wind speed in January
Average humidity in January
Average rainfall in January
Average rainfall days in January
Average sea temperature in January
Average daylight in January
Average sunshine in January
Average sunshine days in January
Average UV index in January
Average cloud cover in January
Average visibility in January

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

January and March mark San Juan's lowest temperatures, averaging a high-temperature of 79.9°F (26.6°C).

Humidity

The average relative humidity in January is 77%.

Rainfall

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

Ocean temperature

In January, the average ocean temperature is 79.7°F (26.5°C).
Note: Surface water temperatures between 77°F (25°C) and 84.2°F (29°C) are perceived as excellent and extremely agreeable for enduring enjoyment in water activities.

Daylight

In January, the average length of the day is 11h and 10min.
On the first day of January, 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.

Sunshine

In January, the average sunshine is 8.8h.

UV index

The months with the lowest UV index in San Juan, Puerto Rico, are January through March and December, with an average maximum UV index of 6. A UV Index value of 6 to 7 symbolizes a high health risk from exposure to the Sun's UV radiation for average individuals.
Note: In January, the UV index of 6 transforms into the following advice:
Skirt overexposure. People with light complexions might get scorched in under 20 minutes. The Sun's UV radiation is at its strongest between the hours of 10 a.m. and 4 p.m. Minimize direct exposure to the sun during this period. Sun-protective clothing, a long-sleeved shirt and pants, a wide-brimmed hat, and UVA and UVB-blocking sunglasses are particularly helpful in blocking UV radiation's harmful effects. Attention! UV radiation is ramped up when reflecting off sand and water surfaces.

Updated: Jun 7, 2024
Published by: Weather Atlas | About Us
Data Sources | Weather Forecasting & Climate

Frequently asked questions

What month is the coldest?

The coldest period, with an average high-temperature of 79.9°F (26.6°C), falls in January and March.

What is the usual temperature for San Juan in January?

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

What is the average humidity in January?

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.

What is the ocean temperature in January?

In January, the average ocean temperature is 79.7°F (26.5°C). For swimming, diving, and other water activities, temperatures between 77°F (25°C) and 84.2°F (29°C) are perceived as very enjoyable and pleasurable for prolonged periods without feeling uncomfortable.

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

In January, the average day length in San Juan is 11h and 10min.

When are sunrise and 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 long on average sun shines in January?

In January, the average sunshine duration is 8.8h.

When is the lowest UV index?

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

How high is the UV index in January in San Juan?

In San Juan, the average daily maximum UV index in January is 6. A UV Index value of 6 to 7 symbolizes a high hazard to health from unprotected exposure to UV radiation.

Today

Tomorrow

Long-term

Year January F M A M J J A S O N D

Dec

January

Feb

Average high temperature

80.8°F 27.1°C

79.9°F 26.6°C

80.1°F 26.7°C

Average low temperature

Average pressure

Average wind speed

Average max. wind speed

10.6mph 17.1km/h

10.4mph 16.7km/h

10.7mph 17.2km/h

Average wind speed gusts

Average humidity

Average rainfall

Average rainfall days

14.5

11.5

11.9

Average sea temperature

Average daylight

Average sunshine

Average sunshine days

9.5

11.1

9.8

Average UV index

Average cloud cover

Average visibility

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: 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: 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: 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: 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: 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: 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: 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: 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: 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: 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: 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).

January weather forecast
San Juan, PR

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