Meteo Santa Teresa (Malpais) in gennaio

January opens the hottest, driest run of the Costa Rican year, with strong sun and lower humidity - and regulars still say to expect some rain most days, generally in the afternoon or at night. Our 22.2 precipitation days across 120.4mm is that, five millimetres a day, and one visitor's accounting is the clearest version: roughly eight hours of rain across a week, five of them after dark. Their weather apps had predicted rain daily. The date worth knowing is the 6th: the first days of January are peak holiday travel, and waiting until after about then means the Christmas crowds have gone and prices ease, though it stays high season. A light poncho and a small umbrella cover it. The record: 28.4C over 24.4C reading as 34C, a 28.9C sea and AQI 33.

Santa Teresa forum threads describe August as genuinely rainy country-wide, with the typical pattern being sunny mornings, a real chance of afternoon rain, and possibly wet overnight stretches too - posters called mid-August 'nice and wet' rather than a washout. The consistent advice was to front-load activities for the morning and treat the area as a place to slow down and relax in the afternoons. Multiple threads flagged that the heaviest rainy season here doesn't really start until the very end of August into September/October, when some restaurants and hotels close for the slow season, meaning earlier August still runs noticeably better than what follows it.

Forum posters place February and March inside Guanacaste/Nicoya's dry season - genuinely dry and dusty by Costa Rican standards, a sharp contrast to the wetter months later in the year. The typical pattern posters describe even in the dry season: sun and partly cloudy skies dominate, with any rain that does show up more likely arriving late afternoon or at night rather than disrupting daytime plans - the standard advice is to schedule surfing, beach time and outdoor activities for the morning and early afternoon regardless of month. Posters consistently name this Pacific Nicoya Peninsula stretch (Santa Teresa included) as one of the more reliably dry corners of Costa Rica during the dry season months.