The calendar says fall arrived a week ago. But in the San Luis Valley, the change of seasons doesn't happen on a single day.

It sneaks up on you.

One morning you walk outside and realize you need a jacket. A few days later, you're scraping the windshield. Then, almost without noticing, the whole Valley has shifted into getting-ready-for-winter mode.

Here are a few of the signs.

The First Frost on the Windshield

At 7,500 feet and up, summer nights never get too warm. But there's always a morning in September when the thermometer dips below freezing and the car is covered in frost.

Suddenly, everyone remembers where they put the ice scraper — or realizes they never replaced the one that broke last winter.

Snow on the Peaks

Look east toward Blanca Peak and the Sangre de Cristos, or west toward the San Juans. After an early fall storm, the highest summits wake up with a fresh coat of white.

It might melt off in a few days. But once you've seen that first dusting, it's hard to pretend summer is still hanging on.

Potato Trucks on the Road

In much of the country, fall means pumpkins. Here, it means potatoes.

Harvest in the Valley generally starts in early September and runs into mid-October. Harvesters roll through the fields, trucks loaded with spuds head for storage cellars, and you learn to be patient behind farm equipment on the county roads.

It's one of the busiest — and most important — times of the year for the Valley's farm families.

The Cranes Come Back

Most people think of spring and the Monte Vista Crane Festival when they think of sandhill cranes. But the cranes pass through in the fall, too.

According to the National Park Service, cranes begin arriving back in the Valley in late September, and some stay through mid-to-late November. Fall arrivals tend to come in smaller family groups rather than the big spring crowds — but that rattling call overhead is just as unmistakable.

The Monte Vista National Wildlife Refuge is usually the best place to look, especially early and late in the day.

The Smell of Roasting Chile

Few smells say “fall in southern Colorado” like green chile tumbling in a roaster.

Families buy it by the sack, roast it, peel it and pack it into freezer bags. Come January, when it's below zero outside, a bowl of green chile stew made from those bags tastes a lot like September.

The Woodpile Grows

Drive through almost any Valley town this time of year and you'll see it: trucks loaded with firewood, and neat stacks growing along fences and against garages.

For households that heat with wood, a good woodpile isn't decoration. It's peace of mind.

Swamp Coolers Get Covered

Here's one that anyone from the Valley will recognize.

All summer, the swamp cooler keeps the house comfortable. Then one fall weekend, somebody climbs up on the roof, shuts off the water, drains the lines and puts on the cover for another year.

And the first chilly night after that, the furnace kicks on for the first time — complete with that familiar dusty smell as it burns off a summer's worth of dust.

Gold on the Mountainsides

From the Valley floor, the aspens show up as streaks of gold on the mountainsides. Head up toward the passes and they surround you.

It doesn't last long. A windy week can strip the trees bare. So people grab a free afternoon, pack a thermos and go look while they can.

Blaze Orange and Friday Nights

Hunting season brings out the blaze orange at gas stations and cafes, and camp trailers heading for the high country.

Back in town, the stadium lights come on for high school football, and the crowd in the bleachers starts showing up in heavier coats and blankets.

Ready or Not

Winter in the San Luis Valley is long, cold and beautiful. The people who have lived here a while know it's easier when you get a head start.

So the hoses come in, the snow shovels come out of the shed, and the heavy coats move to the front of the closet.

Nobody rings a bell to say it's time.

But when you see the cranes overhead and smell chile in the air, you know.