December weather forecast
Caldera, Costa Rica

The first month of the winter, December, is still a warm month in Caldera, Costa Rica, with an average temperature varying between 22.1°C (71.8°F) and 29.7°C (85.5°F).

Temperature

As Caldera welcomes December, the average high-temperature records at a still warm 29.7°C (85.5°F), marking an insignificant deviation from the prior month. During December, Caldera observes a consistent average nighttime temperature of 22.1°C (71.8°F).

Heat index

During December, the heat index is appraised at a torrid 35°C (95°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. Being exposed to direct sunshine might trigger a heat index increase 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. The individual's impression of temperature can be affected by numerous factors such as metabolic variations, physical exertion, and attire. Direct sun rays have a notable impact on perceived temperature, which can raise the heat index by up to 15 Fahrenheit (8 Celsius) degrees. Heat index values are extremely vital to babies and toddlers. Younglings are generally more in peril than adults due to their reduced perspiration. Coupled with a larger skin surface relative to their tiny bodies and greater heat production because of their activity, they become more at risk.
Humans rely on perspiration as a cooling mechanism, wherein the evaporating sweat counteracts excessive warmth. Greater relative humidity lessens the rate of evaporation, thus decreasing the body's heat dispersal, which gives rise to a sensation of overheating. As body temperatures escalate without effective heat release, one might face dehydration threats.

Humidity

In Caldera, the average relative humidity in December is 75%.

Rainfall

In Caldera, in December, during 10.8 rainfall days, 19mm (0.75") of precipitation is typically accumulated. In Caldera, during the entire year, the rain falls for 218.6 days and collects up to 1456mm (57.32") of precipitation.

Daylight

With an average of 11h and 36min of daylight, December has the shortest days of the year.
On the first day of the month, sunrise is at 05:40 and sunset at 17:15. On the last day of December, in Caldera, sunrise is at 05:55 and sunset at 17:28 CST.

Sunshine

In December, the average sunshine in Caldera, Costa Rica, is 9.6h.

UV index

The months with the highest UV index in Caldera are January through September and December, with an average maximum UV index of 7. A UV Index of 6 to 7 symbolizes a high threat to health from exposure to the Sun's UV rays for the ordinary person.
Note: In December, a regular UV index of 7 translates into these guidelines:
Escape overexposure. People with light skin may incur burns in fewer than 20 minutes. Limit your exposure to the sun's UV radiation, which is strongest between 10 a.m. and 4 p.m., and note that parasols or canopies may not provide full sun protection. Combat UV radiation's detrimental effects with sun-safe clothing and UV-blocking eyewear.