Denver streets are no place to spend the night when the mercury drops below zero, but several single, homeless women faced just such a challenge this week due to a shortage of shelter beds.

Even though the number of women affected is small, it’s an appalling reality and ought to be a call to arms.

Despite a comprehensive effort on the part of several city agencies and charities to “end homelessness,” there will always be those who fall through the cracks. But as a community, we should be able to ensure that everyone has access to shelter on nights that can be fatally cold.

Though services for homeless men and for women with children have been built up over decades, the number of single, homeless women — among society’s most vulnerable population — has spiked in recent years, and experts who work with homeless women in Denver say many nights pass without enough shelter beds to go around for these women.

In emergency situations, city officials say 241 beds can be made available for single, homeless women. Shelter officials set the normal number of beds at 125.

That’s just not enough in a city of nearly 600,000 people and a metro area of 3 million.

Tax-supported relief exists at the Denver Department of Human Services, where homeless women who qualify can get up to 12 hotel vouchers a year. But as The Post’s Colleen O’Connor reported, the government relief program is not always reliable at zero degrees.

O’Connor interviewed women turned away from overcrowded shelters and found they rely on survival strategies that include riding buses, hanging out inside Denver International Airport, seeking out all-night businesses to “shop” in, and huddling inside cardboard boxes.

Many women spend full days seeking shelter only to resort to those pitiful strategies, and measures more desperate still.

We can’t always expect government to be the safety net, especially in dire economic times. And we can’t assume there are enough people volunteering at shelters and donating the money and resources required to fill the need.

Readers responding to O’Connor’s reports expressed a desire to help. Beyond donating money to shelters of your choice, here are some real-world actions you can undertake to be part of the solution:

Churches and civic groups could organize volunteers who would be ready to offer housing for a night to one or more single women, says Terrell Curtis, executive director of The Delores Project. The city is trying to establish such a network, but a church group could privately inform shelter operators that they can accommodate a woman or two in emergency situations. That network alone could solve the problem.

Volunteered food, especially meals that can be frozen, are also a great assistance for shelter operators. Linens, blankets and clothing (particularly coats and boots) also help.

“It’s going to take all of us,” Curtis says.

We should answer that call.