The National Forestry Commission (Conafor) said the fire is the worst in the 40,000-hectare federally protected nature zone in the past seven years.
The fire, which began early Saturday morning, has so far affected 1,462 hectares of the forest, according to Susana Mendoza, Confor delegate in Jalisco. Not all this area has been completely destroyed, she added.
By 1 a.m. Monday, 40 percent of the fire had been controlled, she said. Firefighters expected to have the blaze under control before the hottest part of the day around midday Monday.
Mendoza said the fire is the most serious since May 2005, when a massive blaze consumed more than 8,000 hectares of the forest, forcing metro-area schools to close for two days as contamination levels soared.
Although prevailing winds allowed smoke from the blaze to drift across the western part of Guadalajara this weekend, no sudden spike in the city's air quality index was noted.
Authorities suggested the blaze started when a controlled fire to burn garbage in Colonia Arenales Tapatias got out of control.
Firefighters and Civil Protection personnel have been working around the clock to contain the blaze. The state government's helicopter has been ferrying workers in and out of the affected area, which includes the Cerro Pelon, El Mirador, El Picnic, El Ocho y Medio and Las Canoas zones of the forest.
Conafor announced that two of its helicopters will be used from 11 a.m. Monday onward. The choppers have the capacity to dump 1,100 liters of water at a time on the fire.
An unexpected downpour Sunday evening lasting around 30 minutes helped contain the fire to a small degree, Mendoza said.
Education Secretary Antonio Gloria said school principals at campuses located near the blaze zone should determine whether to suspend classes.
Over the weekend, civic-minded citizens bandied together to collect supplies of water and food for the firefighters. Donations also included face masks, eye drops, gloves, helmets and lanterns. The collection point for donations is the OXXO store car park at Periferico and Mariano Otero.