April weather forecast
San Francisco, Costa Rica

In April, San Francisco displays drastic changes in weather patterns, notably the vast increase in rainfall reaching up to 86mm (3.39"). Simultaneously, temperatures remain consistent with March's, denoting the contrast in this monthly transition. Despite the heightened rainfall, sunshine hours stay relatively unaltered, an intriguing balance for inhabitants and visitors alike. The increased precipitation typically triggers notable changes in the surrounding environment. This further reiterates the ever-changing dynamics of San Francisco's weather in Costa Rica.

Temperature

The highest point of temperatures in San Francisco falls in March and April, when the average high-temperature ascends to 29.7°C (85.5°F).

Heat index

April's mean heat index is estimated at a very hot 35°C (95°F). Take more caution, heat exhaustion and heat cramps may occur. Long-lasting activity may cause heatstroke.
It is essential to grasp that the heat index's numbers are for shade and light wind settings. With exposure to direct sunshine, the heat index could climb by 15 Fahrenheit (8 Celsius) degrees.
Note: The heat index, also known as 'feels like' or 'apparent temperature', joins air temperature with relative humidity to produce a temperature perception for humans. Factors such as metabolic variation, pregnancy, and physical activity play a role in one's impression of weather. Awareness is key; direct sunlight can enhance the weather's impact, possibly boosting the heat index by up to 15 Fahrenheit (8 Celsius) degrees. Heat index values remain especially vital for babies and toddlers. Young individuals are typically more threatened than adults due to their reduced perspiration. Also, the larger skin surface proportionate to their small bodies and the increased heat from their activities magnify their risk.
Perspiration is the human body's physiological response to high temperatures and is an attempt to lower body temperature through evaporation of sweat. With high air temperature and humidity (high heat index) conditions, sweat production is restricted, leading to an amplified perception of heat. Overheating can ensue when the body accumulates more heat than it can release, and dehydration severity may vary.

Humidity

In April, the average relative humidity is 73%.

Rainfall

In San Francisco, Costa Rica, in April, during 20 rainfall days, 86mm (3.39") of precipitation is typically accumulated. In San Francisco, Costa Rica, during the entire year, the rain falls for 272 days and collects up to 2217mm (87.28") of precipitation.

Daylight

In April, the average length of the day is 12h and 21min.
On the first day of the month, sunrise is at 05:33 and sunset at 17:46. On the last day of April, sunrise is at 05:19 and sunset at 17:47 CST.

Sunshine

In April, the average sunshine is 9.1h.

UV index

January through April, June, July, September, October and December, with an average maximum UV index of 6, are months with the highest UV index. A UV Index value of 6 to 7 symbolizes a high health risk from unprotected exposure to Sun's UV rays for the ordinary person.
Note: A daily maximum UV index of 6 in April translates into the following instructions:
Avoid excessive sunlight. Those with lighter skin may experience burning in less than 20 minutes. UV radiation from the Sun is most intense between 10 a.m. and 4 p.m. Try to avoid direct sunlight during this period. Your best bet for sun defense on the face, eyes, and neck is a hat with a wide brim.