San José sää — syyskuu

La Fortuna-forum threads on September weather confirm this sits within the wettest stretch of the local year, mornings generally the more reliable window before cloud and a real system build through the afternoon. Posters call the Arenal volcano itself genuinely hit-or-miss for visibility, cloud cover and showers frequently obscuring the peak for stretches at a time. Regulars describe humidity as staying close to saturated throughout, laundry famously refusing to fully air out and a warm afternoon feeling considerably heavier than the same reading in a drier month. Posters recommend scheduling hikes for the morning, afternoon plans genuinely riskier. Regulars call the hot springs and waterfalls worth the trip regardless of volcano visibility, both largely unaffected by a passing shower. Posters recommend real rain gear. The record: 27.5C days feeling like a punishing 33C, 21.4C nights, an extraordinarily high 270mm across nearly 29 days and 92 percent humidity.

Forum posters generally rate August as a good month to visit Costa Rica overall, describing a typical lowland or coastal day as sunny and hot in the morning with rain, sometimes heavy, moving in during the afternoon or evening - a pattern posters say leaves the landscape noticeably greener. San Jose itself, at over 1,100m elevation, runs noticeably milder than those hotter coastal descriptions, with comfortable daytime highs rather than genuine heat. Posters are direct that late August specifically can turn genuinely rainy, and while Pacific-slope rain is usually confined to afternoon and evening, posters emphasize there's no guarantee during rainy season. One visitor's second-half-of-August trip found mostly good weather, though posters are consistent that predicting exact conditions for specific dates isn't really possible. Posters generally rate August as workable and even good for a San José-area visit, rain gear recommended regardless.

February is deep in Costa Rica's dry season, and San José sits at altitude, so it runs cooler than the coasts — near 26°C by day, dropping to 17 at night. "Dry season" is the forum's own phrase and their own caveat: it does not mean it cannot rain, and eight wet days is the record's answer. Regulars pack an umbrella regardless. Two regional notes matter more than the capital's own weather: the Caribbean side is reliably rainier and cloudier than the Pacific in February, and Guanacaste gets serious wind this month while La Fortuna, Monteverde and Manuel Antonio generally do not.