January weather forecast
São Luís, Brazil

January is firmly within São Luís's rainy season, bringing high humidity and frequent rainfall. The month witnesses a temperature range from 23.5°C (74.3°F) as the nightly low to a daily high of 30°C (86°F). Daylight, meanwhile, extends up to 12.3 hours. Notably, the UV index is a maximum 12, urging residents and tourists alike to adopt necessary sun protection measures. As the year nudges into motion, January offers a distinctly moist and warm beginning in São Luís.

Temperature

São Luís, Brazil, experiences an average high-temperature of a still hot 30°C (86°F) in January, marking an insignificant shift from 31.1°C (88°F) in December. During January, the average low-temperature is a warm 23.5°C (74.3°F).

Heat index

In January, the heat index is appraised at a torrid 39°C (102.2°F). Special measures are necessary to avoid heat cramps and heat exhaustion. Persistent activity could result in heatstroke.
Realize that the values for the heat index are set for shaded places and light winds. The heat index has the possibility to be enhanced by 15 Fahrenheit (8 Celsius) degrees when there is direct sun exposure.
Note: The heat index, also known as 'feels like' or 'apparent temperature', blends air temperature and moisture content to represent the felt temperature to humans. The influence of weather is personal, differing among individuals based on variations in body mass, stature, and the degree of physical exertion. Consider that direct sun exposure can intensify the felt heat, adding potentially 15 Fahrenheit (8 Celsius) degrees to the heat index. Heat index values are extremely significant for children. Juveniles often do not understand the need to recuperate and rehydrate. Thirst is a delayed symptom of dehydration - hence, it is vital to maintain hydration, particularly during ongoing physical activities.
Perspiring is how the human body naturally cools down, as sweat's evaporation takes away excess heat. Increased relative humidity interferes with body cooling by slowing the rate of evaporation, resulting in a slower body cooling rate and a heightened feeling of heat. Overheating and potential dehydration arise when body heat gain eclipses its release capability.

Humidity

In January, the average relative humidity in São Luís is 85%.

Rainfall

In São Luís, Brazil, during January, the rain falls for 13 days and regularly aggregates up to 244mm (9.61") of precipitation. In São Luís, during the entire year, the rain falls for 130 days and collects up to 2290mm (90.16") of precipitation.

Sea temperature

In São Luís, in January, the average water temperature is 28.6°C (83.5°F).
Note: Water temperature between 25°C (77°F) and 29°C (84.2°F) is regarded as very warm and enjoyable by all. With these temperatures, water activities are pleasurable, without feeling uncomfortable for prolonged periods.

Daylight

In January, the average length of the day is 12h and 15min.
On the first day of the month, sunrise is at 05:52 and sunset at 18:08. On the last day of January, sunrise is at 06:03 and sunset at 18:17 -03.

Sunshine

In São Luís, the average sunshine in January is 4.9h.

UV index

January through April, September through December, with an average maximum UV index of 12, are months with the highest UV index. A UV Index value of 11, and more, symbolizes an extreme threat to health from exposure to the Sun's UV rays for average individuals.
Note: In January, the maximum UV index of 12 suggests these recommendations:
Put into action all crucial precautions. Defense against sun damage is a must. During the period from 10 a.m. to 4 p.m., UV radiation is highest. Try to avoid direct sunlight during these hours. A wide-brimmed hat provides unparalleled sun protection for sensitive areas like the eyes, ears, and neck. A sunscreen boasting a minimum SPF of 30 should be generously applied and reapplied even on cloudy days, post swim or outdoor exercise. Alert! Sand and water increase UV exposure due to their reflective properties.