San Juan
Puerto Rico, USA
Long-term weather forecast
Long-term weather forecast

January weather forecast and climate
San Juan, PR

An old fort building and a view of the stunning San Juan city, Puerto Rico, with a clear view of the calm waterfront
An old fort building and a view of the stunning San Juan city, Puerto Rico, with a clear view of the calm waterfront
January, like December, in San Juan, Puerto Rico, is a moderately hot winter month, with average temperature ranging between max 83.1°F (28.4°C) and min 72°F (22.2°C).

Temperature

January is the coldest month, with an average high-temperature of 83.1°F (28.4°C) and an average low-temperature of 72°F (22.2°C).

Heat index

The average heat index is calculated to a tropical 89.8°F (32.1°C). Take special precautions - heat exhaustion and heat cramps are expected. Heatstroke may occur with lengthy activity.
Take into consideration that the heat index values are calculated for shade and light wind conditions. With the exposure to direct sunlight, the heat index may be increased by up to 15 Fahrenheit (8 Celsius) degrees.
Note: The heat index, also known as 'felt air temperature', 'apparent temperature', 'feels like', or 'real feel', is a measure that combines both air temperature and relative humidity into a single value that indicates how hot the weather feels. Additional factors like activity, pregnancy, clothing, and wind affect individual temperature impact. Bear in mind that direct sunshine exposure increases weather impact, and may raise heat index by up to 15 Fahrenheit (8 Celsius) degrees. Heat index values are particularly important for children. Children are often less aware of the need to rest and re-hydrate. Thirst is a late sign of dehydration - it is vital to remain hydrated, particularly during prolonged physical activities.

Humidity

In San Juan, the average relative humidity is 74%.

Rainfall

In San Juan, in January, during 17.6 rainfall days, 4.6" (116mm) of precipitation is typically accumulated. In San Juan, during the entire year, the rain falls for 198.5 days and collects up to 70.6" (1794mm) of precipitation.

Ocean temperature

In January, the average ocean temperature is 79.7°F (26.5°C).
Note: 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.

Daylight

The average length of the day in January is 11.2h.

Sunshine

In San Juan, the average sunshine is 7.7h.

UV index

January and December, with an average maximum UV index of 8, are months with the lowest UV index in San Juan. A UV Index estimate of 8 to 10 represents a very high health risk from the exposure to the Sun's UV radiation for average individuals.
Note: In January, the average maximum UV index of 8 translate into the following recommendations:
Take extra precautions. Protection against sun damage is required. Seek shade and minimize exposure to direct Sun in a period between 10 a.m. and 4 p.m. when UV radiation is most intense; keep in mind that shade structures like parasols or canopies do not provide perfect sun protection. On bright days sunglasses that block both UVA and UVB rays should be worn. A hat with a wide brim is extremely helpful, as it can prevent roughly 50% of UV radiation from reaching the eyes. Beware! The reflection of water and sand dramatically increases exposure to the UV rays.

What is the coldest month in San Juan?

The coldest month in San Juan is January, with an average high-temperature of 83.1°F (28.4°C) and an average low-temperature of 72°F (22.2°C).

What is the temperature in January in San Juan?

In San Juan, in January, the average high-temperature is 83.1°F (28.4°C), and the average low-temperature is 72°F (22.2°C). The average heat index (a.k.a. 'felt air temperature', 'apparent temperature'), that combines both air temperature and relative humidity, in January is evaluated at 89.8°F (32.1°C).

What is the average humidity in January in San Juan?

In January, the average relative humidity in San Juan is 74%.

How many days does it rain in January in San Juan?

In San Juan, during January, the rain falls for 17.6 days and regularly aggregates up to 4.6" (116mm) of precipitation.

How warm is the water in January in San Juan?

In San Juan, in January, the average water temperature is 79.7°F (26.5°C). For any water activity, surface water temperatures between 77°F (25°C) and 84.2°F (29°C) are considered as excellent and extremely pleasant for lengthened periods.

What is the average length of the day in January in San Juan?

The average length of the day in January in San Juan is 11.2h.

How long on average sun shines in January in San Juan?

In San Juan, the average sunshine in January is 7.7h.

What are the months with the lowest UV index in San Juan?

January and December, with an average maximum UV index of 8, are months with the lowest UV index in San Juan, Puerto Rico.

What is the UV index reading in January in San Juan?

In San Juan, the average daily maximum UV index in January is 8. A UV Index value of 8 to 10 symbolizes a very high health risk from the exposure to the Sun's UV radiation.
Average temperature in January - San Juan, PR
  • Average high temperature in January: 83.2°F

Warmest months (with the highest average high temperature) are August and September (89.2°F).
The month with the lowest average high temperature is January (83.2°F).

  • Average low temperature in January: 72°F

The month with the highest average low temperature is August (78.2°F).
Coldest months (with the lowest average low temperature) are January and February (72°F).

Average humidity in January - San Juan, PR
  • Average humidity in January: 74%

The month with the highest relative humidity is October (76.9%).
The month with the lowest relative humidity is March (71%).

Average rainfall in January - San Juan, PR
  • Average rainfall in January: 4.6"

The wettest month (with the highest rainfall) is August (7.7").
The driest month (with the lowest rainfall) is March (3.1").

Average rainfall days in January - San Juan, PR
  • Average rainfall days in January: 17.6 days

Months with the highest number of rainy days are November and December (19.6 days).
The month with the lowest number of rainy days is March (12.2 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: 11.2h

The month with the longest days is June (Average daylight: 13.2h).
The month with shortest days is December (Average daylight: 11h).

  • Average sunshine in January: 7.7h

Months with most sunshine are March and July (Average sunshine: 9.1h).
The month with least sunshine is November (Average sunshine: 6.7h).

Average UV index in January - San Juan, PR
  • Average UV index in January: 8

Months with the highest UV index are March, April, May, June, July, August and September (UV index 12).
Months with the lowest UV index are January and December (UV index 8).