By the time John Sheils spotted the pothole on Summer Street in South Boston, it was already too late.

“It almost knocked the fillings out of my teeth, I hit it so hard,’’ said Sheils, a Weymouth resident who hit the pothole in late December and got a flat tire. “All the lights on my dashboard lit up.’’

Later, Sheils said, he logged on to Boston’s 311 website to report the road defect and learned another person had flagged it two days earlier.

Boston officials have an ambitious goal to fill potholes within one working day of identifying the rim-bending, tire-flattening craters. But their record for meeting that benchmark is mixed, figures show.

The city said it met the one-day benchmark for 82 percent of the potholes it has identified so far this year — about 2,800 craters.

But another measurement, CityScore, the system that looks at Boston’s response to individual constituent requests, shows the city has come up short on potholes. The goal for that standard is to fill 80 percent within a day — but on that measurement, the city said it fills 59 percent of potholes within the one-day goal.

Chris Osgood, chief of streets for Mayor Martin J. Walsh, said public works crews are trying to pick up the pace when it comes to filling potholes — including those flagged by constituents.

“It is a target that we are mindful about and we want to be able to hit it,’’ he said. “We’re still closing a large number of cases and a majority of those cases in that 24-hour period. We look forward to being able to hit [the target] with greater regularity.’’

With Walsh’s blessing, the city set the 24-hour goal in the fall of 2015 after finding it was handily meeting a target of filling potholes within a 48-hour period.

Last year, the city said it patched 79 percent of its 9,355 potholes on time — those discovered by the city and reported by constituents. In 2016, 77 percent of the 4,925 potholes were filled on time.

During the record-breaking winter of 2015, 57 percent of 7,159 potholes were fixed within 48 hours as the city put most of its resources into snow removal, Osgood said.

The one-working-day turnaround time affords some leeway for weekends. For example, if a pothole is discovered at noon on Friday, pavers have until Monday to patch it and have it count toward the city’s benchmark, the city said.

But during the winter months, when the weather swings from freezing temperatures to stretches of thawing, the battle to contain potholes sends public works crews scrambling to keep pace with the crumbling asphalt.

“The potholes are all over the place,’’ said Sheils, who has been commuting to Boston for work for 25 years. “You’re looking more for the potholes than you’re watching the traffic because there are so many of them.’’

And the number of potholes reported to the city’s 311 system increased last month to 1,846, up from 1,567 during January 2017, city data show. Some of the reports, however, pertain to potholes that the city isn’t responsible for fixing because they’re on a state road or near manhole covers maintained by private utilities.

In most cases, the roller-coaster temperatures and wide-ranging weather conditions are the culprit.

National Weather Service data show there were five significant storms last month, starting with more than 13 inches of snow dumped on the city Jan. 4. A week later, nearly 2 inches of rain fell over two days, followed by more snow at the end of January.

The cycle of freezing conditions followed by a thaw allows water to seep into small cracks in the pavement and expand, causing the asphalt to buckle beneath the weight of passing cars.

The amount of asphalt city pavers used to repair the roads also increased. As of last Friday, the city had gone through 254 tons, compared to 187 tons during the same period last year, Osgood said.

The road hazards cost both the city and motorists.

Over a five year period, the city paid more than $163,000 to reimburse drivers for damage their vehicles incurred after striking potholes, figures show. The city spends about $6 million annually and repaves about 30 lane miles each year, Osgood said.

Marc Angelone said he had just begun his commute home from work on Jan. 18 when his car struck a pothole in front of the Boston police district station on New Sudbury Street.

The impact flattened both passenger side tires and upset the vehicle’s alignment, requiring a flat bed truck to tow Angelone’s Audi A6 to a dealership in Peabody, he said.

The following day he reported the pothole to the city, Angelone said, and within a few days it was filled.

“It was a relatively quick,’’ said Angelone, a lawyer who commutes to the city from Methuen.

Ten public works employees are assigned to combat these road nemeses throughout the year, but during pothole season their ranks can swell to 40 workers on a given day, Osgood said.

The city’s strategy for battling is potholes is twofold, Osgood said.

During good weather, paving crews resurface streets — work that Osgood said the city coordinates with construction schedules for utility companies and others that might have to dig up roads.

When pothole season arrives in the winter and spring, the strategy shifts to deploying enough staff and the right equipment to areas where potholes open up, he said.

Annissa Essaibi-George, an at-large city councilor, said her office has fielded complaints about potholes, particularly on state roads that are maintained by the Massachusetts Department of Transportation.

“There’s just a lot of frustration that the city and the state haven’t been able to keep up with the demand,’’ she said.

Jeferson Schueng said he was driving his family to church on Jan. 14 when he struck a pothole at the intersection of Saratoga and Bennington streets in East Boston. He filed a claim with the city, seeking $115 to cover the cost of replacing the tire he blew on his Chevrolet Cruze.

The city rejected the claim and referred Schueng to Eversource because the pothole he said he struck had opened up next to a manhole cover controlled by the utility.

Schueng, who lives in Winthrop, said he was so annoyed by the city’s response that he threw the notification in the trash.

“I was really frustrated,’’ he said. “Our state is very expensive. We should get better roads.’’

Matt Rocheleau of the Globe staff contributed. Laura Crimaldi can be reached at laura.crimaldi@globe.com. Follow her on Twitter @lauracrimaldi.