Fredi Onan Vicen Peña, the coffee farmer whose brothers, sister and teenage son have already given up and joined the exodus north, reached over and tore a leaf off one of his plants.

It was a mottled yellow and brown: signs of coffee rust, a disease whose spread has been influenced by climate variability. As much as 70 percent of his crop, planted across five acres in a pine forest, had been affected, he estimated, and there was little chance he could salvage it.

“Climate change is destroying some farms,” said Mr. Vicen, 41.

Beyond that, some of his healthier plants had begun to blossom nearly two months ahead of schedule because of a heavy unseasonable downpour, throwing the entire growing cycle into doubt.

“This is not something we predicted,” Mr. Vicen said.

Average temperatures have risen by about two degrees Fahrenheit in Central America over the past several decades, making the cultivation of coffee difficult, if not untenable, at lower altitudes that were once suitable.

That has forced some farmers to search for land at higher altitudes, switch to other crops, change professions — or migrate.

“Some very fine families that have been producing quality coffee for a long time are now facing the decision of whether to stay in coffee,” said Catherine M. Tucker, a professor of anthropology at the University of Florida who has done research in Honduras for more than two decades.