The highest day temperature in December 2025 was 84°F. The lowest night temperature was 51°F. The average values for day and night temperatures during December were 80.5°F и 56.5°F respectivly.

The average sea surface temperature in December 2025 for Alajuela was 86.8°F. The maximum and minimum values were 86.0°F and 87.6°F respectively.

Most of the days in December are cloudy but you can also expect sunny or gloomy days.

Precipitation total in December for Alajuela is 3.1 in. It makes december one of the least rainy months of the year.

The average wind speed in December is 5.4 mph. It makes December one of the most windy months of the year for Alajuela.

We are using day length and cloud cover information for each day of the month to calculate averages for this chart. Average sunny hours for Alajuela in December is 6.8 hours.