September sits just past the peak. The Southern Hemisphere is still producing and the Tola reefs still get their swell, a little less often than in August but at the same kind of size. The lake wind is unchanged.
What has changed is the number of people. The July and August season is over, the camps have space, and prices come down. It is also the wettest stretch of the Nicaraguan year, which is the trade you are making. Bring a jacket for the evenings and expect to lose an afternoon or two. The water is at 29°C, so nothing about the rain is cold.
