San Mateo Weather in December
San Mateo in December sees high temperatures, with highs around 29°C (84°F) and overnight lows of 21°C (70°F). Rainfall is fairly high at around 130 mm (5.1 in) on average, so pack waterproofs just in case.
Rainfall in San Mateo in December
Based on our climate data of the past 30 years, about 13 days of rain are anticipated, with 130 mm (5.1 in) on average. When showers do arrive, they tend to be on the heavier side. Worth being prepared even if rain days are not that numerous.
Temperature in San Mateo in December
Daytime temperatures in San Mateo reach 29°C (84°F) in December, dropping to 21°C (70°F) at night. Overall, the month follows a fairly predictable daily temperature pattern. Nights are mild at around 21°C (70°F), which is comfortable for most people.
Sunshine in San Mateo in December
Expect sunny days throughout the month, with an estimated 233 hours of sunshine. This makes it a pleasant time to visit San Mateo.If you're inclined towards comfortable temperatures and drier conditions, December is a good time to visit San Mateo.
Check the conditions for any month of the year.
For a detailed overview over the year and the best time to visit Costa Rica, check out our San Mateo's climate page.
San Mateo Temperature in December
Min Temperature
21°C (70°F)
Max Temperature
29°C (84°F)
Chance of Rain
44%
Precipitation
130 mm (5.1 in)
Rainy days
13 days
Sunshine
233 hours *
Percentage Sunshine
*
Daily Historical Temperatures
44-year average (1976-2025)
Based on our historical records, temperatures in San Mateo typically stay consistent throughout December, with daily highs averaging around 29°C (84°F). Nights are pleasant, with lows around 19°C (66°F).
Average temperatures in December
Daily Historical Precipitation
44-year average (1976-2025)
Average daily rainfall for each day of the month based on long-term records.
Average precipitation in December
Historical weather for San Mateo in December
Browse day-by-day weather records for San Mateo spanning 51 years. Select any month and year to see actual temperatures, rainfall, and conditions recorded on each day.
San Mateo historical weather extremes in December
According to our 29 years of weather records for San Mateo, the following extremes were recorded between 1996 and 2025.
- San Mateo recorded its highest December temperature of 33°C (91°F) on December 20, 1997.
- On December 11, 2017, San Mateo saw its coldest December day with temperatures maxing out at 21°C (70°F).
- The lowest overnight temperature recorded in December was 13°C (55°F) (December 7, 2010).
Best Places in Costa Rica in December
Find out more about the weather in Costa Rica and which places have the best travel conditions in this month. See all of Costa Rica in December →
perfect weather
pleasant
tolerable
unpleasant
poor
What to Wear in San Mateo in December
Warm temperatures in December make for comfortable sightseeing weather. Pack breathable fabrics like cotton shirts, knee-length shorts or skirts, and comfortable walking shoes. A thin long sleeve for indoor spaces is handy. Prepare for significant rainfall with proper waterproof clothing and shoes. Don't forget sun protection, sunglasses, sunscreen, and a hat. These are all good ideas with this much sunshine.What To Do in San Mateo in December
We rated the following activities from 1 (least suitable) to 10 (best) to do.
Check the conditions for any month of the year.
For a detailed overview over the year and the best time to visit Costa Rica, check out our San Mateo's climate page.
See the full San Mateo climate overview or explore weather in Costa Rica.
