Our Summer 2015 Greatest Hits series continues with this useful post on the best time to plan your trip back to LA after your Vegas vacation. Read on to save yourself some valuable time!

While what happens in Vegas may stay in Vegas, there’s one thing that Sin City just can’t contain within its neon-colored walls: traffic. If you’ve ever made the drive to or from LA, you know that traffic can stretch a four hour trip into a seven hour nightmare. With one road — I-15 — as your only option to get through the Nevada desert, a single accident can back things up considerably and choosing the right time to leave Las Vegas is a gamble all to itself. The good news? If it’s any day but Sunday, you’re probably fine (unless it’s the Monday of a holiday weekend — in which case you’re totally screwed, bro). On Sunday, though, it’s all about playing the percentages.

The first thing to note is that the majority of the ride is smooth-sailing. Once you get past the Nevada-California border, you may hit little traffic snarls but they’ll almost always be the results of accidents that shut down a full lane of traffic — there are only two lanes in both directions for most of the journey on the 15 — and they’ll never be as intense as the HoseBeast that is the lane reduction snag found at the border. Yes, the “Agricultural Inspection” checkpoint in Yermo, CA slows things down but it’s nothing compared to what happens in Primm, NV at the state border. As such, we’re going to use the border traffic data as our indicator here. (Note: if you’ve got traffic in Primm, you’ll have traffic in Yermo — since it’s one road the whole way back, the amount of cars you’re traveling with won’t really change along the way).

Let’s go to Google Maps for some data. Using the Google Maps predictive traffic tool (the one where you click “Traffic at day and time” instead of “Live Traffic”), here are the traffic patterns you can expect from the moment when traffic usually backs up (10:30am) until the moment it clears again (8:00pm):

To break it down, we can see that it’s all green until 10:15am:

At 10:30, things already start to back up (the yellow line):

It gets worse and worse from there. By the time you get to 1:30pm, you’re in the middle of the eight circle of Hell with traffic stretching all the way to Jean, NV — a full 12 miles from the border:

At that point, you may as well have stayed at the blackjack table for another few hours because it doesn’t really start to clear up at all until 3:30pm (and trust me, it’s still a mess at 3:30) and not fully clear until 8:15pm. Yikes.

So when is the best time to drive from Vegas to LA on a Sunday? Since Vegas to Primm (the border town) is roughly 40 miles, give or take, assume that it’ll be approximately 45 minutes to get there. You’re in the green until 10:15, so leaving at 9:30am at the latest in the morning should get you through without stop-and-go traffic at the border. Later on, things are fairly dicey until 6:30pm at the earliest, which means leaving after 5:45pm is your best bet.

Now, this all comes with the caveat that I left Vegas yesterday at 2pm and I got back to LA at 6:45, so the traffic only added 45 minutes to my drive. It’s very unpredictable. Sometimes that four hour drive becomes seven hours. Sometimes it’s 4.5 hours. It really all depends on what was going on in Vegas that weekend.

Bottom line: the best time to drive from Vegas to LA on a Sunday is before 9:30am or after 5:45pm.