Time to Visit

I would possibly change my recommendations based on when you would plan to come. The country's dry season is mid-Dec through April. Rainy season starts May-November. I would avoid Sept or Oct. They are our rainiest months. But of course, Arenal volcano is rainforest, so you can get rain any time of the year. But if you decided to come during rainy season I would recommend the beaches closer to us because we are the driest area of the country so the chances for full days of rain would be less with us than the other pacific coast like Manual Antonio. For our area, rainy season usually means sun in the morning and early afternoon and then rain late afternoon/evening, which is fine, because all year round here in Costa Rica in general, it gets dark around 530pm (note this for planning purposes because I wouldn't recommend driving at night here long distances).

But there's usually an annual sweet spot about mid-July to first week of august where we get a week or two or three (all depending on the year) of less rain all around the country. We can't always pinpoint when it will happen, but man, it's the best time all year because everything is so green and we get clear skies and no rain.