December weather forecast
Umatac, GU

Rounding off the year, December in Umatac, Guam features a further decline in rainfall to 2.99" (76mm), a drop from November's already reduced precipitation. This downward trend marks the cessation of the rainy season. Despite a decrease in glory, the weather radiates a gentle elegance with its subtropical warmth and winds. Sunshine hours narrow marginally, allowing for comfortable daylight use. Notwithstanding the cooler season, the UV index remains consistent, advocating for year-round sun protection practices.

Temperature

Umatac, Guam, records a slight change with December's average high-temperatures adjusting to a still warm 83.5°F (28.6°C) from November's 84.2°F (29°C). Umatac, in the month of December, notes an average low temperature of 82°F (27.8°C), indicating a small decrease from the daytime highs.

Heat index

In December, the average heat index is computed to be a hot 91.4°F (33°C). Take more safety measures, heat exhaustion and heat cramps are potential outcomes. Persistent activity might lead to heatstroke.
It is crucial to understand that heat index figures are for shade and gentle wind conditions. Heat index values have the potential to be boosted by 15 Fahrenheit (8 Celsius) degrees due to direct sunlight.
Note: The heat index, also known as 'felt air temperature' or 'real feel', reflects the feeling of heat when considering both air temperature and humidity. This effect tends to be personal, with the weather perception differing among individuals due to variations in body mass, height, and 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 highly important for children. Children often fail to understand the importance of rest and rehydration. Thirst is a late manifestation of dehydration - hence, it is crucial to stay hydrated, especially during ongoing physical activities.

Humidity

The months with the highest humidity in Umatac are January, March through May, October through December, with an average relative humidity of 78%.

Rainfall

In Umatac, in December, during 22.8 rainfall days, 2.99" (76mm) of precipitation is typically accumulated. In Umatac, during the entire year, the rain falls for 288.5 days and collects up to 60.08" (1526mm) of precipitation.

Daylight

December has the shortest days of the year, with an average of 11h and 24min of daylight.
On the first day of December, sunrise is at 6:28 am and sunset at 5:52 pm. On the last day of the month, sunrise is at 6:43 am and sunset at 6:05 pm ChST.

Sunshine

In December, the average sunshine is 6.5h.

UV index

The months with the highest UV index in Umatac are January through August, October through December, with an average maximum UV index of 7. A UV Index reading of 6 to 7 represents a high health hazard from exposure to the Sun's UV rays for average individuals.
Note: The maximum daily UV index of 7 during December translates into the following directions:
Use measures and accept sun safety conventions. Guarding against skin and eye trauma is of high priority. 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. Sun protection is enhanced with clothing that boasts a tight weave yet offers a loose fit.