May weather forecast
São Luís, Brazil

May presages a shift in São Luís's weather, with a relative decrease in rainfall to 317mm (12.48"), signaling the approaching end of the wet season. Temperatures consistently loiter in the warm range. The solstice is a month away, bringing about subtle reduction in daylight hours to 12 hours from past months. Consistent with previous months, the UV index is recorded at 11. With ever-present humidity, May can still bring episodes of heavy rains, albeit fewer than the preceding months in São Luís.

Temperature

São Luís experiences a transition to a hot 30.1°C (86.2°F) in average high-temperatures with the arrival of May, not greatly differing from April's 29.6°C (85.3°F). Throughout the month of May, São Luís sees a steady low-temperature average of 23.1°C (73.6°F).

Heat index

The heat index in May is appraised at a scorching 41°C (105.8°F). Extra precautions are necessary, heat cramps and heat exhaustion are plausible outcomes. Extended activity could lead to heatstroke.
It is important to note that the heat index values are for shaded areas and light wind scenarios. When under direct sunshine, the heat index may be elevated by 15 Fahrenheit (8 Celsius) degrees.
Note: The heat index, also known as 'apparent temperature' or 'felt air temperature', represents the fusion of temperature and moisture in the air to suggest how warm it feels. The individual's experience of temperature can be shaped by numerous aspects such as metabolic variations, physical exertion, and attire. Take note that direct exposure to the sun can increase the felt temperature, possibly adding 15 Fahrenheit (8 Celsius) degrees to the heat index. Heat index values are especially crucial for babies and toddlers. Young ones often disregard the necessity to rest and hydrate. Thirst usually indicates advanced dehydration - hence, it is key to stay hydrated, particularly during ongoing physical activities.
In the face of high temperatures, the human body's reflex is to perspire, leveraging sweat evaporation for cooling. When relative humidity is on the rise, it curtails evaporation, thereby reducing the heat elimination from the body and causing the feeling of being excessively hot. Overheating and dehydration threats arise when heat gain goes beyond what the body can comfortably shed.

Humidity

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

Rainfall

In May, in São Luís, the rain falls for 20 days. Throughout May, 317mm (12.48") of precipitation is accumulated. Throughout the year, there are 130 rainfall days, and 2290mm (90.16") of precipitation is accumulated.

Sea temperature

In São Luís, in May, the average water temperature is 28.7°C (83.7°F).
Note: Water activities including swimming and diving at temperatures from 25°C (77°F) to 29°C (84.2°F) are deemed very pleasurable and enjoyable for extended periods, devoid of discomfort.

Daylight

In São Luís, the average length of the day in May is 12h and 0min.
On the first day of May in São Luís, sunrise is at 05:53 and sunset at 17:54. On the last day of the month, sunrise is at 05:55 and sunset at 17:54 -03.

Sunshine

In May, the average sunshine in São Luís is 5.2h.

UV index

In May, the average daily maximum UV index in São Luís is 11. A UV Index value of 11, and more, symbolizes an ultimate health vulnerability from unsafe exposure to UV radiation for ordinary individuals.
Note: The maximum UV index of 11 during May translates into these guidelines:
Practice every precaution of necessity, unprotected skin and eyes might burn in minutes. Stay in the shade and avoid direct Sun exposure from 10 a.m. to 4 p.m., a time when UV radiation is at its strongest, and remember that parasols or canopies do not offer full protection. Sunglasses that ward off UVA and UVB rays play a pivotal role in reducing solar eye damage. Ensure the liberal application and reapplication of a broad-spectrum SPF 30+ sunscreen after each outdoor activity or swim, and every two hours. Stay alert! Reflective properties of sand and water amplify the Sun's UV radiation.