HISTORICAL MONTHLY AVERAGES FOR DECEMBER
The information presented below gives detailed historical monthly average weather conditions along with exceptional weather occurrences. To maintain relevance to current weather trends the displayed information has been calculated using data collected over the past two decades. The climate profile is taken from closest available data source to St Martin.
Throughout the month of December daytime temperatures will generally reach highs of around 29°C that's about 84°F. At night the average minimum temperature drops down to around 24°C, that's 76°F.
In recent times the highest recorded temperature in December has been 32°C that's 90°F, with the lowest recorded temperature 20°C, about 68°F.
The average daily relative humidity for December is around 74%.
The Heat Index is a measure of how hot it feels when relative humidity is added to actual air temperature. From this a comfort level is calculated providing categories on how heat conditions might adversely affect someone.
Comfort Levels: Given average maximum temperatures and humidity levels caution is advised. Fatigue is possible with prolonged exposure and/or physical activity for those in high risk groups of possible heat disorders (see heat index for more information).
The average monthly amount of precipitation has been recorded at around 91 mm, that's 4 inches. Throughout the month you can expect to see rain or drizzle falling on 21 days of the month.
Estimated Hours of Sunshine per Day
We calculate sunshine hours per day using our past forecast data. For December expect the sun to shine for an average of 9 hours per day. This represents the average number of hours in the daytime that the sun is visible and not obscured by cloud e.g. the average number of hours the sun is actually out and shining. Note we calculate hours of sunshine per day using our past forecast data, not observation data, thus it is an estimate and not actual.
The average daily wind speed in December has been around 17 km/h, that’s the equivalent to about 10 mph, or 9 knots. In recent years the maximum sustained wind speed has reached 93 km/h, that’s the equivalent of around 58 mph, or 50 knots.
On average the month of December is not affected by foggy conditions.
SWIMMING AND WATER TEMPERATURE
The temperature of water an individual will feel comfortable in is very much personal preference. What feels unbearably cold to one person for a swim might be fine for another. We have created our own Swimming Water Temperature Index offering a guide to water temperature and comfort levels for swimming;
In December, for the nearest coastal location, the temperature of the sea averages around 27°C, that's 81° Fahrenheit. Our index indicates for swimming in this is considered very warm and would be enjoyed by all. With this temperature you can stay active in the water for extended periods of time without feeling uncomfortable.
YEARLY TRENDS: WEATHER AVERAGES & EXTREMES
The following charts show yearly weather trends with information on monthly weather averages and extremes.
The chart below plots the average high and low temperature for each month of the year. It also shows the maximum and minimum recorded temperatures.
The chart below plots the average monthly precipitation amount.
The chart below plots the average number of days in any month that you can expect to see rain falling.
The chart below plots the average daily wind speed you can expect for any month. It also shows the maximum recorded sustained wind speed for each month.