Forget gold, or platinum, or saffron. 

The rarest commodity -- in Philadelphia at least -- might be a perfect day. 

Metro asked the Pennsylvania State Climatologist at Penn State University to count the number of near-perfect days residents in Philadelphia can expect.

Our definition: 60 to 75-degrees, mostly sunny, with a slight breeze. The scientists checked their database. Those conditions, at least as recorded at the Philadelphia International Airport, had to hold for any eight-hour period during daylight hours.

The scientists searched their database, going back 67 years to 1948. They found that residents of the city can expect just 8.7 days of near perfect weather per year. 

We’re optimists. We’ll call it 9.

“Nine days? That’s so sad!” said Jen Heany, 20, a Drexel sophomore who was studying on Independence Mall on Wednesday. “When I come outside, I’m happy to see the sun. Some people take it for granted, but knowing it’s nine days definitely changes my perspective.” 

According to the data, there have been just 583 such days between Jan. 1, 1948 and Dec. 31, 2014, There have been 119 in May, 171 in September and 139 in October. We get, according to the data, just under three days per spring. 

One might dispute our definition of the perfect day -- but we chose it for a simple reason: hot coffee makes as much sense as short sleeves in this type of weather. A pick-up game of baseball doesn’t cause you to break a sweat. Such days are so nice that they cause us to forget our allergies. 

It’s the type of day that neither air conditioning nor home heat can beat. 

Kyle Imhoff, the assistant state climatologist who conducted the analysis, said that one reason our perfect days are so rare is because a good wind from the west or northwest usually leads to cloud cover in Philly. 

But it was an analysis he’d never performed. Most people, he said, ask about more extreme weather events. 

For Kyle Hoffman, a carriage driver who works near Independence Mall, the key to a good day is all in the forecast. He makes his money when people decide to take advantage of good weather. 

“If they call for rain and we have a nice day, people can’t plan for that,” Hoffman said. “But if they call for a nice day, people come out in droves.”

“But knowing it’s just nine days? I makes me want to take less coffee breaks and more time getting business.”

The forecast says Monday will be sunny, with highs in the mid-seventies. Maybe a little higher, but good enough.

Take our advice: skip work.