The absolute best time to visit Costa Rica is during the dry season, which runs from mid-December to April. This period, often called "Verano" (summer) by locals, offers the most consistent sunshine and the least amount of rainfall, making it ideal for exploring the rainforests, lounging on the Guanacaste beaches, and hiking the Arenal Volcano. December and January are particularly popular because the landscape is still lush and green from the preceding rains, but the weather is clear. If you want to avoid the peak "holiday" crowds and high prices of Christmas and Easter, February and March are fantastic alternatives with near-perfect weather. For those on a budget who don't mind a few daily showers, the "shoulder" months of May and June (the start of the "Green Season") offer a great balance; the crowds disappear, hotel rates drop, and the rain usually falls in the late afternoon, leaving the mornings clear for activities. Conversely, you may want to avoid September and October on the Pacific side, as these are the wettest months where some rural roads can become impassable due to heavy tropical downpours.