Best time to visit Costa Rica

Best months: January, February and December
Year: 2001-2020
Spread between cities: 19 (in May)

The answer for Costa Rica is computed across 2 measured cities, and there January, February and December come out best on the twenty year normals for 2001-2020. That is an average of real places rather than a figure for the country as a whole, because no such figure exists.

All 2 cities put January among their own best months, so this is one of the rare countries where the answer holds wherever you go.

The measured cities in Costa Rica stay close to one another all year, so one answer for the country is honest here rather than a simplification.

The numbers behind that: January averages 24.9 degrees across the measured cities, from San José at 22.7 to Liberia at 27.1, and brings about 21 mm of rain.

The months to avoid are October and September, and what decides it is the rain.

Each month is scored on its mean temperature, its rainfall and its humidity, taken from the provider twenty year normals for 2001-2020. The cities are San José and Liberia. The comfort bands and the penalties are fixed and published, so a reader who disagrees with the ranking can see exactly which part of it they disagree with.

The source publishes a monthly mean and, separately, the highest and lowest values it recorded in twenty years. Those extremes are not a typical afternoon or a typical night, so nothing here is quoted as one. This page does not say what the daytime high usually is, because this source cannot say it.

Normals are not a forecast. They describe what twenty years averaged to, and any single year can sit well outside them. They also describe a model grid cell of roughly fifty kilometres rather than a weather station, so a coastal city and the sea beside it share one figure.