Ramana,

You may look at Nicaragua weather files. Managua the capital of Nicaragua is located at Lat. 12 deg N Lat. and Long. 86 deg W or Rivas in Nicaragua located at Lat. 11 deg N and Long. 85.8 deg W and San Jose' the capital of Costa Rica located at Lat. 9 deg N and Long 84 deg W. These cities are close to each other and have similar tropical climatic conditions and hence for your purpose this may be a quick and easy option.
Otherwise, you may contact some authority in Costa Rica that records the weather, it could be either the local government of that city or the airport.

Best regards,

Gaurav