May is just one month away from summer
May is just one month away from summer. For the top half of the planet, this means the sun rises earlier and sets a little later with each passing day. That steady increase in solar power warms up the atmosphere, which in turn shuts down most storm/swell production over the Northern Oceans.
Since the Northern Hemisphere is mainly out of action this month, the search for a reliable source of swell must cross the equator and enter the Underworld of the Southern Hemisphere. The Southern Hemi is like Bizarroland, where everything is opposite: there's the Antarctic ("opposite to the Arctic"), low-pressure systems circulate clockwise, highs turn counterclockwise and the seasons are reversed.
So while we're warming up towards summer, the bottom half of the world is cooling down into winter and storm activity is on the rise. The past few months have already been very productive in the Southern Oceans -- and should continue to pump, as diminishing sunshine drives the atmosphere deeper into storm mode.
Now that we know where the swells are coming from, we just have to pick a good spot where they'll end up. Southerly exposure is the most essential requirement -- and southwest exposed areas are best of all, since that's the end destination for most Southern Hemi swells. Distance is important, both to limit swell decay and travel time/cost from the US.
A quick glance at the globe shows that most of the Pacific side of Central America meets those criteria. A closer look: Nicaragua is the largest country in Centro, yet it gets fewer visitors than Costa Rica, its more popular neighbor; Nica's topography creates nearly perpetual offshore winds in the southern part of the country; water temps average around 80 degrees and the weather is always warm. While May is technically the start of the wet season, this month generally remains mostly dry.