There are a lot of storylines heading into Monday night's preseason game against the Denver Broncos, the biggest of which might be the return of San Francisco 49ers quarterback Jimmy Garoppolo. The Niners' signal-caller did not play in the team's preseason opener, and the game at Mile High Stadium will be his first in-game action (even though it is just preseason) since he suffered a season-ending ACL injury nearly 11 months ago.

Another storyline might be the heat Garoppolo will be under. No, I'm not talking about the Broncos' pass rush or the injuries to the offensive line. I am literally talking about the heat.

The Denver altitude isn't the only thing 49ers players will have to deal with on Monday night. The game is expected to be in the low-to-mid 90s at kickoff, which could make it the hottest in Broncos history, according to the Denver Post.

"If Monday's kickoff temperature is 93 degrees or above, it'd be hotter than any Denver Broncos game in team history," writes Chris Bianchi of the Denver Post. "The current record is a 92-degree kickoff temperature, set just last September. Three preseason games also have featured a kickoff temperature of 92 degrees, most recently a 2010 exhibition against the Detroit Lions."

The heat could be an advantage for 49ers players, who have become used to high temperatures during August and September kickoffs. Preseason games at Levi's Stadium are purposely scheduled with later start times to protect fans from the August heat inside the structure.

49ers veteran tackle Joe Staley, who has played at both Levi's Stadium and Candlestick Park, was recently asked to describe his current home field and he came up with one word.

"Hot," Staley told Melissa Jacobs of The Football Girl. "It's hot. But it's because of the hot air, I guess, it's hot in there. I don't know what it is."

Kickoff between the 49ers and Broncos is scheduled for 5 p.m. PT / 6 p.m. MT, and the game can be watched on ESPN.

H/t to Cam Inman of Bay Area News Group for the find.