The blaze was fueled by the mown straw stubble and by a long row of round, straw bales.
Flames shot nearly 25 feet in the air as the straw burned.
Firefighters managed to stop the blaze before it hit an abandoned house and two other buildings, said Independent Fire Chief Ed Smith.
A large cloud of black smoke was visible from the south end of Charles Town as the blaze burned up about eight acres of J.P. Burns's farm.
Smith said that the heat and the lack of rain have made conditions ripe for field fires.
"If we don't get some rain soon this will become more of a problem," Smith said.
In the Berkeley County blaze, the fire started about 9 a.m. Sunday in a field at the Slonaker Farm on McCubbins Hollow Road about two miles south of Glengary, W.Va., said Back Creek Fire Chief Jerry Swain.
The 50-foot by 50-foot barn was a total loss as well as numerous tools and other equipment inside, Swain said.
The cause of the fire was accidental, Swain said.
The barn was used as a workshop and many of the tools inside were considered antiques, Swain said.
Damage was estimated at $85,000 to $100,000, Swain said.
The firefighters fought to keep the blaze from destroying two nearby buildings, both damaged by heat from the fire, Swain said.
The firefighters had the fire knocked out in about 10 minutes but remained on the scene until about 12:30 p.m., Swain said.
The barn had collapsed and firefighters had to raise the old timbers to get at the embers, Swain said.