Ocean experts at the Universidad de Costa Rica say that both coasts can expect high seas Friday and thereafter.
The choppy conditions in the Caribbean are blamed on a high-pressure area in the North Atlantic and a low-pressure area near Colombia.
In the Pacific a low -pressure system in the south is producing waves of up to 12 to 16 meters. These will be reduced to about 3.5 meters, about 11.5 feet, when they reach Costa Rica, said the Centro de Investigación en Ciencias del Mar y Limnología. The waves will be less in the central and north Pacific, the Centro said.
On both coasts, a small-boat warning has been issued, and bathers are urged to use caution, said the Centro.
The Centro also said that although the waves are not expected to be high, there might be some difficulties at high tides.
The Centro urged coastal dwellers to be vigilant.