John Staley, 18, of Hagerstown, was also playing Wiffle ball at Byron Memorial Park. He said the light rain falling Sunday afternoon wasn't interfering with their celebration.
"I'm out here celebrating my best friend's birthday," he said.
Friday's temperature reached 72 degrees - possibly a record high for this time of year, according to Dean DeVore, an AccuWeather meteorologist. Saturday's high temperature was 65, while Sunday's high was slightly cooler at 60 degrees.
DeVore said today's temperatures were expected to reach the low 70s.
Laura Newberry of Smithsburg said Sunday's weather was perfect for her and her running partner, Doug Poster, also of Smithsburg.
They both ran nearly 10 miles on the C&O Canal towpath near Williamsport.
"It was perfect for me," Newberry said. "Not too hot, and the drizzle felt good."
Light rain fell steadily for most of the day. About 5 p.m., with the sun peeking through thick clouds, several bass fishermen were returning to the boat ramp in Williamsport.
Lenny Wilt of Boonsboro said he spent six hours fishing for smallmouth bass Sunday.
He said the weather was cold and rainy for most of the time he spent on the water.
"Water temperature is really the only thing that affects the fishing, though," Wilt said.
He said before he started fishing Sunday, he and another man debated whether they should even go out. Temperatures were expected to reach 70 degrees Sunday, and Wilt realized early that they would fall short.
"It would just be better for us," he said. "It was pretty cold."
Mike Zindel of Hagerstown and his neighbor, Keith Lovelace, each caught four smallmouth bass Sunday on the Potomac River.
"It was OK," Zindel said of the weather. "It rained most of the day, but it was not too bad. Sometimes it's better fishing that way."
A thunderstorm was expected for late tonight, DeVore said.
"That will usher in much colder weather," he said.
By the end of the week, temperatures should be in the 40s, according to AccuWeather reports. By Friday, there is a chance of rain or snow in the area.