For those curious how well outdoor dining holds up as the weather cools, researchers at the global investment firm Goldman Sachs have made their call. Colder than 45 degrees, they said, and interest in patio (and parking lot) dining doesn't just decline, it sinks like a stone.

The current forecast for Sunday here in St. Paul calls for a high of 42. While weather that cold might discourage normal people from dining outside, we are about to find out if that's also true for Minnesotans.

We knew this week was coming. A lot of services have moved outside this year, not just dining and beer drinking. Going outside only made more sense as understanding of the novel coronavirus that causes COVID-19 has grown.

Earlier this month, and after more than a little controversy, the Centers for Disease Control and Prevention acknowledged that tiny particles with the virus can stay airborne for a while and infect people more than 6 feet away.

"Ventilation and avoidance of crowded indoor spaces are especially relevant for enclosed spaces," the agency wrote, "where circumstances can increase the concentration of suspended small droplets and particles carrying infectious virus."

The figure that shows up time after time in the news is that it's about 19 times more likely for the virus to spread indoors than outdoors. It's from a Japanese study early in the global coronavirus pandemic, and its presence on an Environmental Protection Agency guidelines page suggests it has held up pretty well.

That's why wearing a face mask remains a no-brainer. There's also been a lot more talk about proper ventilation.

The state's guidance for restaurants and bars even has standards for the right kind of ventilating system filters, preferably a MERV-14 rated filter or better. Maybe restaurant owners knew all about MERV filter ratings before this year, although that hardly seems likely.

A writer for the Atlantic this week noted that public officials seem to veer from alarmist to overly reassuring about socializing indoors, so she tried to assess the risks, asking public health professors for help. Part of their answer hinged on the rate of spread in a community, measured by things such as the positive rate of tests and average new cases.

No more than five to 10 daily average confirmed cases of COVID-19 per 100,000 people was one rule of thumb, while another professor was a little more forgiving at 25 average daily cases.

If just five to 10 daily confirmed cases per 100,000 people is the standard for indoor socializing to be low-risk, Minnesotans have some work to do. The recent number for Ramsey County is more like 20 cases — fewer than the state as a whole and less than half the recent totals in more than a dozen Minnesota counties.

You can see why restaurant owners dread what's coming. Half of diners don't feel comfortable eating indoors, the president of Morrissey Hospitality of St. Paul told a colleague recently, with no expectation that will change until the pandemic subsides.

Given that, Goldman Sachs seemed to have a surprisingly optimistic view of restaurant sales nationally, although the industry is big enough for the expected dip in fourth-quarter sales to take a bite out of economic growth. But, of course, in much of the country it can be warmer than 45 on a winter day.

Even newcomers to our state know what's coming here. Sunsets slip to around 4:30 p.m. in December, not that we are likely to see them. November is the cloudiest month of the year in much of Minnesota, December in the rest. Let's not even talk about December's daily low temperatures.

And no, Minnesotans shouldn't treat this like a normal winter.

Earlier this week, a veteran science writer for the New York Times wrote a hopeful article about how the health care field really has made remarkable progress on COVID-19, and not just with the amazing pace of vaccine development. He can finally see the eventual end of the pandemic.

Yet as close as vaccines and more effective therapies now seem, they are still a way off. In the meantime, he wrote, quoting the infectious disease expert Anthony Fauci: "We need to hunker down."

We're going to do our part in our house, although we remain committed to helping local businesses make it to next year, too. We will buy more restaurant meals for pickup at the curb and include stops to pick up those giant cans of beer from local breweries, too.

We are also unwilling to simply stay inside until March, planning to invite others to go outside with us. Together we will try to prove the lesson hikers and hunters try to teach, that there's no such thing as bad weather, only bad gear.

We have accumulated a closet of vests and jackets, boots, hats, mittens, socks and "base layers," although it would be fine with me if REI Co-op just sold that stuff as warm underwear.

In the back of our house there's also now a new stainless-steel fire pit, one of my wife's good ideas for something we ordinarily never would have even thought about buying. It looked so sharp out of the box I hated to start a fire in it. As for what it cost, I decided not to ask.

It works great.

None of this is to suggest that winter is going to be easy, with the need to maintain social distancing and still not live in grim isolation. An hour around a backyard fire might prove to be a long time come December, when in past winters the get-togethers by a living room fireplace might have lasted until the wine was gone.

Back in the spring I ran across an essay by the spiritual writer Anne Lamott, and she wrote that she had asked a friend and priest how they were ever going to make it through some trying period. "Left foot, right foot, left foot, breathe," he responded.

That reminds me to make sure the daughter who borrowed my snowshoes last winter returns them. I'm going to need them.

lee.schafer@startribune.com 612-673-4302