Pianos need to be tuned! The longer a time between tunings the harder (and more expensive) it is to bring the piano back into tune.
Tune you piano at least once a year. Try and have it tuned at the same time each year.
A serious player, student, singer, or player piano should consider tuning twice a year.
We recommend tuning after the start of the rainy season in May, and again when the rainy season is over and the weather cools down in November.
There are several good tuners in the area, may we recommend Phil Bondi His web site is philbondi.com