* Direct land hit not expected
* No major oil installations on Pacific side
* Central American countries brace for heavy rains (Updates with new storm strength, quote)
GUATEMALA CITY, July 18 (Reuters) - Tropical storm Dora, the fourth named storm of the Pacific hurricane season, strengthened off the coast of Central America on Monday, threatening heavy rains on the coffee and sugar growing region.
The storm, with winds of about 60 mph (95 kph), could reach hurricane strength on Tuesday but is not forecast to make a direct hit on land and there are no coastal warnings in effect, the U.S. National Hurricane Center said.
"Additional strengthening is expected during the next 48 hours," the NHC said. "And Dora is forecast to become a hurricane on Tuesday."
Dora is located south of Guatemala and southern Mexico and is moving up the Pacific coastline, which does not have major oil installations.
The NHC said swells caused by Dora would probably begin affecting the coast of southern Mexico on Tuesday.
"The swells are likely to cause life-threatening surf and rip current conditions," the center added.
Heavy rains have already drenched Central America this year, putting the vulnerable countries at risk of floods and landslides that could also affect export crops.
Two people died and three are missing in Guatemala due to rains last week, said national emergency officials. (Reporting by Mike McDonald in Guatemala City and Mica Rosenberg in Mexico City; Editing by Eric Beech)