January is typically a dead zone at the box office, which is one reason no one expected much from "Insidious: The Last Key."

After all, it's a poorly-reviewed fourth installment of a horror franchise that seemed to be running out of gas with the third chapter three years ago, which debuted with the franchise's weakest opening ($22.7 million) and limped out of theaters just ten weeks later, the shortest run of any movie in the series -- with the lowest total gross of any "Insidious" movie ($52.2 million). It's no wonder that almost no one thought "Last Key" would open any higher than $22 million, though some pundits predicted a premiere as low as $16 million.

And yet, Sunday's estimates have it opening in second place, with a robust $29.3 million, averaging a strong $9,392 per screen. That's the second best opening of the series, behind only the $40.3 million debut of "Insidious Chapter 2" four years ago. It was enough to push "Star Wars: The Last Jedi" into third place, after the film spent three weeks atop the chart (it fell to an estimated $23.6 million in its fourth weekend). If not for the still strong "Jumanji: Welcome to the Jungle," which estimates placed at a remarkable $36.0 million in its third weekend, the fourth "Insidious" would have premiered in first place.

How did "Last Key" scare up so much money and shock the experts? Here are five ways.

1. January Is a Good Month for Horror
Studios have known this for some time, getting horror fans to open their wallets in January for such films as "Cloverfield" (opening with $40.0 million in 2008), "The Devil Inside" ($33.7 million in 2012), and "Mama" ($28.4 million in 2013).

Last year, Hollywood really made January a terrifying month, with "Split" (a $40.0 million debut), "The Bye Bye Man," and the underperforming horror-action thrillers "Underworld: Blood Wars" and "Resident Evil: The Final Chapter." So audiences were primed for a scary movie this month, especially since there won't be another for four more weeks, when we get "Winchester" on February 2.

2. "The Last Jedi" Just Doesn't Have the Legs of a Typical "Star Wars" Movie
That seems odd, given that it took just two weeks for "Last Jedi" to become the top-grossing movie of 2017 and three weeks to earn more than "Rogue One" did over its five-month run. Still, two years ago, "The Force Awakens" held on to first place for four weeks, not three.

Last year, "Rogue One" fell from first after three weeks, but at least it spent its fourth week at No. 2. "Last Jedi" started stronger than "Rogue One," but its fall feels steeper (it's lost 89 percent of its debut business, compared to 86 percent for "Rogue One" at this point in its release). That could be because fan fondness for this chapter hasn't been as strong, with opinions much divided over the sequel's plot and character choices. But it's also because the last two movies didn't face a mainstream competitor that stole much of their thunder...

3. Audiences Wanted Something New This Weekend
That would be "Last Key" and "Jumanji," whose take this week is just $169,000 shy of its opening-weekend tally. Nothing else that has opened lately has captured that kind of fervor or enjoyed that kind of holding power.

So again, escapism-seeking audiences, who had no other new options, were going to turn out in force for "Insidious," regardless of how little critics thought of it. Sure, it drew just a 25 percent Fresh rating at Rotten Tomatoes and even a lackluster B- grade among paying customers at CinemaScore, but what else was there?

4. There Are Few Movies Out There That Young Women Want to See
Jessica Chastain and Idris Elba in MOLLY'S GAMEYeah, there's "Pitch Perfect 3," though that has failed to spark the kind of enthusiasm that the first two movies enjoyed. And there's "The Last Jedi," overflowing with role models.

Still, nothing caters to younger female audiences like horror. Everything else out there seems aimed either at young men ("Jumanji") or at older viewers -- namely, all those Oscar-hopeful movies. With the Golden Globes kicking off the awards-show season in earnest this weekend, such films as "Molly's Game" and "Darkest Hour" expanded into more than 1,000 theaters each and saw solid box office boosts. ("Molly" earned an estimated $7.0 million this weekend, while "Hour" picked up an estimated $6.4 million.)

Also seeing boosts were Oscar-seeking movies that are still playing in just a handful of theaters -- "I, Tonya," "The Post," "Hostiles," and "Phantom Thread." These will be movies for box office observers to keep an eye on in the coming weeks. But that also means that younger viewers will have to settle for the likes of "Insidious."

5. Not Even Snow Storms Could Keep Audiences Away
The winter storm that buried much of the eastern United States in snow at midweek was expected to keep theaters shuttered and discourage moviegoing. But the cinemas are back open, and cabin-feverish fans are eager to get out and see something, anything.

If they've already seen "Star Wars" and "Jumanji," at least there's another familiar franchise film, one that offers indoor chills that are worth braving the outdoor chills for.