Altitude determines the climate throughout Costa Rica. Areas below 3,000 feet have average annual temperatures of around 80°, with little variation from month to month. The temperature drops from around 74° at 3,000 feet to 59 degrees at 5,000 feet. Above 5,000 feet, the average annual temperatures can range as low as 40 degrees to the mid-50s, with occasional frost during the coolest months.
The temperature in San Jose is generally pleasant, with two seasons distinguished mainly by the rainfall. The dry season runs from December through April and the wet season extends from May through November. Even during the wet season the mornings generally are clear, with the afternoons and evenings dominated by heavy rains nearly every day. Relatively high winds often are present during the dry season.
The average temperature in San Jose is 70 to 75° Fahrenheit. In December, the coolest month, the average temperature drops to around 65°. Temperatures drop into the 50s at night throughout the year. Humidity in San Jose averages 80 percent annually.