Western El Salvador is the country's most mountainous region. At its heart are the Santa Ana, Izalco and Cerro Verde volcanoes, the centerpieces of Parque Nacional Los Volcanes. Further north, there's a high-altitude triumvirate of another sort: the borders of El Salvador, Guatemala and Honduras meet at the cloud-forested summit of Cerro Montecristo, at a point aptly dubbed El Trifinio. The western region also includes Lago de Coatepeque, a beautiful crater lake at the foot of Volcán Santa Ana, and Lago Guija, on the Guatemala-El Salvador border, and numerous rivers. In the westernmost corner of the country is Parque Nacional El Imposible, El Salvador's most famous national park, and one of its last and best-preserved primary forests.
The climate here can be quite cool, with temperatures averaging 12°C to 20°C (54°F to 68°F). You'll appreciate having a light sweater, especially at night in high elevations and during the rainy season (May to November).