The seasons for the Nationals and the Redskins traditionally overlap for about the month of September, with Washington’s baseball team winding down and its football team cranking up. This year, as the Nationals push into the postseason for the first time since baseball returned to the District, the teams will play concurrently for longer — just at a point when the popularity of both appears on the rise.

With the two teams at home Sunday and playing simultaneously for the first time this year, a new Washington Post poll shows a significant increase in Washington area sports fans who view the Nationals and the Redskins favorably. For the Nationals, the percentage of fans who have a strongly favorable view of the team has doubled from a year ago — from 18 to 36 percent — rivaling even the Redskins, who have been entrenched in town for nearly 70 years longer.

The enthusiasm is easy to trace for both franchises. Since arriving in 2005, the Nationals haven’t had a winning season until this year, when they are close to clinching the National League East title. Buoyed by high-profile draft picks Bryce Harper and Stephen Strasburg and led by colorful veteran Manager Davey Johnson, they have been in first place all summer and could finish the season with the best record in baseball, a contender for what would be Washington’s first World Series title since 1924.

The Redskins, who won three Super Bowls a generation ago, traded for the right to draft Heisman Trophy-winning quarterback Robert Griffin III in April. Griffin’s spectacular regular season debut earlier this month brought new hope to a franchise that hasn’t won its division since 1999.

“The appeal factor is not just winning, to me personally,” said David Brandt, 53, of McLean. “It’s winning with the right kind of people. I think a lot of the [Redskins’] ascendance, and the Nats’ too, has to do with some of the characters involved. You’ve got people like RGIII, and the Harpers and the [Ryan] Zimmermans,” he said, referring to the Nationals third baseman, who has played his entire eight-year career in Washington. “That makes a huge difference, having the right people.”

While previous polls — as well as other measures, such as television ratings and merchandise sales — have long shown the Redskins to have a significant hold on the region’s sports fans, this season has helped the Nationals make inroads across a wide array of demographics, the poll showed. Sixty-six percent of sports fans hold a favorable view of the Nats, up from 61 percent last summer. The percentage of unfavorable views of the Nats fell to just 7 percent.

The jump in strongly favorable ratings for the Nationals is most pronounced among men. A year ago, just 15 percent of men had a strongly favorable view of the Nationals. That percentage rocketed to 45 percent this year. The increase is most significant among white men — a 36 percentage-point increase to 48 percent. More than half of white men 50 or older (54 percent) now hold strongly favorable views of the Nationals, a 38-point increase from last year.

Though ratings among men are up for both the Nationals and the Redskins, the baseball team has now surpassed the football team in the strongly favorable category. Last year, 25 percent of men held strongly favorable views of the Redskins as opposed to just 15 percent for the Nationals. Now, the Nationals hold a 45 percent to 33 percent advantage.

Some fans give the family of Theodore N. Lerner, which purchased the team from Major League Baseball in 2006 and preached a slow, grow-from-within approach, credit for sticking to the plan in developing a winner.

“The Lerner family, under the daily direction of [General Manager Mike] Rizzo, they’ve done an excellent job,” said Sam Hyder, 64, of Upper Marlboro. “They have gotten rid of some of the players they were paying too much for with little production. And I think the biggest, most productive move was bringing in Davey Johnson. He knows baseball. He knows the players. He’s helped make them winners.”

Still, the Redskins — who play their first home game of the season at FedEx Field on Sunday — are viewed favorably by a majority of area fans, and increasingly so over the last year. Favorable views of the Redskins are up from 55 percent a year ago to 62 percent, with strongly favorable views up from about a quarter of fans to a third. Negative views have dropped from 34 to 22 percent for a franchise that has enjoyed just two winning seasons in the last 12.

Now, Griffin’s arrival signifies the potential for change.

“I’ve always liked them just as much,” said Robert Gez, 24, who grew up in Darnestown as the son of a Redskins fan and now lives in the District. “But in terms of the chance to win the Super Bowl, it feels better. Every Redskins die-hard fan, you get so hopeful at the beginning of the season. Hopefully it’s different this year.”

The Redskins, who arrived from Boston in 1937, predate any of the other major professional sports teams in town — basketball’s Wizards, hockey’s Capitals, soccer’s D.C. United and the Nationals. They remain most popular among African American sports fans, Maryland residents, those who are less affluent and those without college degrees.

But the Nationals’ rise, on the field and in popularity, comes at a time when the Capitals are coming off five straight playoff appearances and now sell out all their home games. Those developments, said Capitals and Wizards owner Ted Leonsis, could show that Washington is maturing as a sports town.

“This means we have a fantastic community,” Leonsis said. “The Nats are growing. The Caps have grown. The Wizards are growing. The Redskins are doing great. Fantastic! That’s a great thing. It shouldn’t be Redskins versus everyone else. No. We want this to be a world-class sports town.”

To that point, one possibly concerning element to the Nationals: More than one in four respondents were unable to rate the team. With October baseball approaching, and a Washington representative in the playoffs for the first time since 1933, that may be getting ready to change, too.