We can expect desert-like temperatures when the Cardinals visit the 49ers in Week 5

The most significant number to know may have nothing to do with the San Francisco 49ers or Arizona Cardinals .

That number would be 97, as in 97 degrees. The Weather Channel predicts a high of 97 degrees for Santa Clara on Sunday, which means it'll be around 90 at kickoff. For some reason, in recent years–probably global warming, but I only know things about football–October has been a second summer in Northern California. And with another early-fall heatwave hitting the area, Levi's Stadium won't be an envious location.

The high temperature may benefit the 49ers and Cardinals, who are both looking to heat up after a slow start to the season.

See what I did there?

Ahem. Anyway, let's get to the football numbers.

The Arizona Cardinals have 19 pressures as a team, per Pro Football Reference–PFR records pressures as hurries+knockdowns+all sack plays–second-fewest in football. Arizona's 15.4 pressure rate is the third-lowest, according to PFR.

Pro Football Focus has Arizona down for 42 pressures on their film hatchbacks, the fewest in the league. For context, the "struggling" 49ers pass rush has recorded 73 pressures.

No matter which number you put to it, the Cardinals' pass rush has had issues rushing the passer over the first month. Dennis Gardeck leads Arizona in almost every pass-rushing category, with six pressures–the fewest pressures to lead a team in the NFL, per PFF–three sacks and five tackles for loss. Close behind him is Zaven Collins, with four pressures and a sack, and L.J. Collier, who has four pressures but has yet to finish one for a sack.

Brock Purdy, through the first games, has shown Arizona will be damned if they do get pressured and damned if they don't. When kept clean, Purdy has the eighth-highest passer rating at 106.6, completing 74.7 percent of his passes for 881 yards and a pair of touchdowns. It should be noted, however, that both of Purdy's interceptions occur when the offensive line holds up. There's not much of a drop-off to Purdy's numbers on the 37.7 percent of the time he is pressured, with a passer rating of 101.7 with three touchdowns for 252 yards on 39 attempts.

Arizona's pass rush has been slow out of the gates, and it won't get much easier with Purdy's recent form.

Arizona's pass defense completion percentage against is 78.6, the highest in the league.

Oh, did I mention that Arizona's secondary doesn't remedy the lack of a pass rush? Josh Allen, Matthew Stafford, Jared Goff, and Jayden Daniels combined to throw only 22 incomplete passes on 103 passes in the Cardinals' first four games. Of the five defenders with the most pass snaps on the Arizona defense, only one–slot cornerback Garrett Williams–has allowed a completion percentage lower than 80 percent.

In Arizona's defense, they've faced the fourth-fewest pass attempts this season, and smaller sample sizes lead to higher percentages. With that, the Cardinals have allowed just 833 passing yards through the first four games, which puts them near the middle of the pack in the league.

On the other hand, Arizona has allowed 8.6 yards per attempt, which is the fourth-highest average in the NFL. That doesn't match well against Purdy, who leads the NFL at 9.3 yards per attempt. Entering Week 5, Purdy is only 52 yards behind Geno Smith's league-leading 1,182 passing yards but on 21 fewer pass attempts.

Purdy has been uber-productive and playing the best football of his young career. The Cardinals pass defense might need to conjure up a spell to stop Purdy and the 49ers offense on Sunday.

This number counts for two things on the Arizona offense.

Let's start with James Conner, who has scored a touchdown in four of five games against the 49ers since joining the Cardinals in 2021. Conner's average game against the 49ers hasn't been the best, averaging 61.0 rushing yards on 14 attempts in the five games, but he has scored six touchdowns, five on the ground and one through the air.

The two team's most recent matchup was Conner's most consistent, averaging 6.1 yards per attempt on 14 carries with a touchdown in the Cardinals' Week 14 45-29 loss.

Four also represents the number of touchdown receptions by Marvin Harrison Jr so far in his rookie season, tied with Justin Jefferson for most in the league.

After a Week 1 that saw Harrison with three targets and the image of the rookie wide open on what would have been a game-winning touchdown, Harrison has seen at least six targets in each of the last three games, hauling in 14 passes for 239 yards and three touchdowns. He's also scored at least one touchdown in every game since Week 1, with two against the Rams back in Week 2.

Conner and Harrison, along with Kyler Murray, have been the stars of the Arizona offense, combining for seven of the team's nine touchdowns. However, the Cardinals have scored only 27 points in the two weeks since scoring 41 in the team's last win against Los Angeles.

The 49ers have won its last four games against the Cardinals with a plus-88-point differential.

Since 2022, the 49ers have averaged a win against the Cardinals by a score of 39-17, with three 30-point performances and, most recently, one 40-point performance. The domination started with the Mexico City game in Week 11 of 2022, with San Francisco blowing out Arizona 38-10. A few months later, the 49ers would score 38 points again, beating Arizona by 25.

Kliff Kingsbury got fired after 2022, and Jonathan Gannon came in for 2023, but the results weren't much different. The 49ers would again sweep Arizona by a combined score of 80-45.

But the most recent game between the two–the 49ers' 45-29 win in Week 15 last season–Arizona was the closest they've come during the streak, losing by 16. It was also the first game the Cardinals were with Murray against the 49ers since Arizona's sweep of its division rival in 2021. Arizona hasn't exactly rolled out an all-star lineup of quarterbacks against the 49ers during the skid, with Colt McCoy, Trace McSorley, David Blough, and current 49er Joshua Dobbs getting snaps in the three games before Murray's return last season.

Arizona will hope the closer Week 15 game with Murray is more reflective on Sunday's result than the other three games against San Francisco since 2022.