March weather forecast
São Luís, Brazil

The month of March brings the most precipitation to São Luís, with 428mm (16.85") of rain spread across 23 days, the highest throughout the year. As temperatures inch from 23°C (73.4°F) at night to 29.4°C (84.9°F) in the day, humidity also scales upward. The length of the day, however, slightly decreases, amounting to 12.1 hours of daylight. With the UV index sustained at 12, residents maintain vigilance against sun harm. March encapsulates the pinnacle of São Luís's rainy season with its significant rainfall and stubborn humidity.

Temperature

São Luís's lowest average temperatures are recorded in February and March, reaching a high of 29.4°C (84.9°F).

Heat index

In March, the average heat index is appraised at a torrid 38°C (100.4°F). Adopt heightened preventive measures, heat exhaustion and heat cramps are probable. Persistent activity could lead to heatstroke.
Given the heat index, its values are aligned with shaded sites and gentle winds. The heat index values could be amplified by up to 15 Fahrenheit (8 Celsius) degrees in direct sunlight.
Note: The heat index, also known as 'felt air temperature' or 'real feel', is a single figure representing how weather conditions feel when combining temperature and humidity. The effect is personal, with varied weather perceptions among individuals due to differences in body mass, stature, and physical activity. 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 especially vital to children. Children are often less aware of the need to rest and re-hydrate. Thirst is a late sign of dehydration - it's vital to remain hydrated, particularly during prolonged physical activities.
To prevent overheating and help regulate its internal temperature, the human body sweat and rely on the evaporation to cool down. In conditions of both high temperature and humidity (a high heat index), sweating is limited and the perception of heat is enhanced. Potential thermal conditions emerge as the body's heat gain outpaces its cooling mechanisms.

Humidity

In São Luís, the average relative humidity in March is 89%.

Rainfall

In São Luís, Brazil, in March, during 23 rainfall days, 428mm (16.85") of precipitation is typically accumulated. In São Luís, during the entire year, the rain falls for 130 days and collects up to 2290mm (90.16") of precipitation.

Sea temperature

The month with the warmest seawater is March, with an average sea temperature of 28.9°C (84°F).
Note: For any water activity, the surface water temperatures in the range of 25°C (77°F) to 29°C (84.2°F) are deemed excellent and incredibly pleasant for longer durations.

Daylight

The average length of the day in March in São Luís is 12h and 7min.
On the first day of March in São Luís, sunrise is at 06:04 and sunset at 18:14. On the last day of the month, sunrise is at 05:58 and sunset at 18:03 -03.

Sunshine

With an average of 3.5h of sunshine, March has the least sunshine of the year.

UV index

The months with the highest UV index in São Luís are January through April, September through December, with an average maximum UV index of 12. A UV Index estimate of 11, and higher, represents an ultimate health vulnerability from unsafe exposure to UV radiation for the ordinary person.
Note: The maximum daily UV index of 12 in March converts into the following recommendations:
Practice all essential precautions. Protection against sun damage is crucial. Stay in the shade and avoid direct Sun exposure from 10 a.m. to 4 p.m., a period when UV radiation is particularly strong, noting that parasols or canopies may not offer total sun protection. In bright sunlight, prioritize sunglasses that grant protection from UVA and UVB radiation. Even on overcast days, a sunscreen with a sun protection factor of no less than 30 should be generously applied and reapplied, particularly after swimming or outdoor activities. Heads up! UV intensity is amplified by reflections from water and sand.