Two new studies confirm that Bay Area rents are softening, after years of double-digit increases.

The San Francisco metro area saw average rents decline year over year for the first time in more than six years last month, according to a survey by Dallas research firm Axiometrics.

The average rent for all apartment sizes in San Francisco, San Mateo and Marin counties was $3,287 a month in July, down 0.7 percent from $3,309 in July of 2015. That was its first such decline since April 2010.

Most of that drop happened in the latter part of 2015. The average rent has risen since January, but not enough to offset last year’s drop, an Axiometrics spokesman explained.

In the San Jose-Sunnyvale-Santa Clara metro area, the average monthly rent in July was $2,857, up only 0.3 percent from July of last year. That was its smallest increase since April 2010.

And in the Oakland-Hayward Berkeley area, rents in July averaged $2,432, up 2.3 from July of last year, its smallest increase since June 2010.

The moderation in rents follows years of stratospheric increases that have inspired more Bay Area communities to consider, adopt or strengthen rent control. Burlingame, San Mateo, Mountain View, Oakland, Alameda and Richmond have renter-protection measures on the November ballot.

Axiometrics surveys apartments with 50 or more units that have been open for at least 13 months. Its numbers are adjusted for concessions, such as a month of free rent.

In the San Francisco metro area, concessions peaked in April, when they averaged 0.6 percent of monthly rent value. In July, they were just 0.2 percent. However, concessions are much more common in new properties that are being leased for the first time, and these properties are not in the survey, a spokesman explained.

He attributed the rent weakness to a slowdown in job growth and apartment construction. About 11,600 new units are expected to hit the market in the San Francisco, San Jose and Oakland metro areas this year. That’s up from roughly 7,000 last year. Next year’s total is expected to drop to around 10,000.

“What I have seen, in the last 30 to 60 days, is rents flattening out and then a concession on top of it rather than decreasing the asking rent,” said Jeff Bosshard, president of multifamily operations with Woodmont Real Estate Services, which manages apartments throughout the Bay Area, except in San Francisco.

“We have been spoiled by double-digit rent growth over the last four years. I don’t see our year-end numbers being double digit. They will be mid-single digits — 4 or 5 percent, maybe 6 to 7 percent in stronger markets.”

A survey from Novato research firm Real Answers also shows a slowdown in rent increases. Like Axiometrics, it surveys complexes with 50 or more units, but reports the average rents quarterly (rather than monthly) for each county (rather than metro area).

In San Francisco, the average rent hit $3,595 in the second quarter, up 2 percent from the second quarter of last year, but down 0.7 percent from the first quarter of this year. That was the highest average rent, and the smallest year-over-year appreciation, in the nine-county Bay Area.

For the Bay Area as a whole, rents averaged $2,526 in the second quarter, up 4.3 percent from the same period in 2015 and up 1.8 percent from the first quarter of this year.

The rental market “is definitely plateauing,” said Joe Stokley, owner of Stokley Properties, which manages rental properties ranging from one to 40 units in the East Bay. High-end properties that cost $5,000 to $7,000 a month are taking longer to rent. “Possibly there is more on the market (in that price range) and less people able to afford them. Properties that are $3,000 or less, they don’t stay on the market very long.”

“Things are definitely slowing down,” said Benjamin Scott, founder of Advent Properties, which manages rentals in San Francisco and the East Bay.

“We are seeing a lot of concessions ... especially in SoMa, where there has been a glut of new apartment properties coming online at once.” Those concessions, such as reduced deposits or a month of free rent, “are reverberating” throughout the city.

Scott’s firm has had a two-bedroom apartment on Sumner Street on the market at $3,495 for a month. It has had a one-bedroom condo on Buena Vista Avenue with parking, also at $3,485, on the market for three weeks.

He said some owners are reluctant to lower their rent because they upgraded the property in anticipation of rising rents, or the unit is rent-controlled and they don’t want to lock themselves into a lower rent.

Kathleen Pender is a San Francisco Chronicle columnist. Email: kpender@sfchronicle.com Twitter: @kathpender

Bay Area rents leveling off

Average monthly rent for three metro areas

Metro Area Average rent July 2016 Change from July 2015 San Francisco $3,287 -0.7% Oakland 2,432 2.3 San Jose 2,857 0.3

Source: Axiometrics