With the arrival of summer come familiar sensations: sand between your toes, sun on your shoulders, and the pinch at the pump. Every year, gas prices go up because of the infamous “summer mix.” Don’t know what that actually means? We didn’t either, so we spoke with Dan McTaag, GasBuddy’s Senior Petroleum Analyst, to find out why gas prices are rising this summer.
1. Winter Gas Prices
The first part to understanding why gas prices are rising is understanding how gasoline behaves under different temperatures. Gasses are easier to ignite than solids or liquids, but frigid winter temperatures mean less evaporation. “In the winter, when [there’s] colder weather out there, you want to make sure your gasoline’s spark point – its ignition point, its flammability – is a little bit higher,” says Dan. There’s a measurement called RVP, which stands for Reid Vapor Pressure. Vapor pressure basically refers to evaporation – and evaporation affects volatility, or how flammable this mix is. In cold temps, refineries might add stuff that encourages more evaporation. “They might be putting in products like butane,” says Dan, which is also put in lighters. “Butane is a wonderful igniter, and you use that in the winter; it’s cheaper.” So the stuff you have to add to the winter mix is cheap!
2. Why Gas Prices Are Rising This Summer
But in the summertime, things are different. “When we see warm weather, we don’t want gas to expand; it could evaporate and it could also explode or ignite,” shares Dan. Explosions would obviously ruin anyone’s road trip – but mostly that increased evaporation is bad for air quality, which is why the EPA regulates summer gas. “To reduce that volatility in gasoline, they have to add alkylates, which means it’s more expensive,” radds Dan. And the cost of stuff they add to make summer gas less gassy is passed along to you at the pump – usually about ten cents a gallon.
3. Supply & Demand
Okay, the fuel mix isn’t the only factor when discussing why gas prices are rising. The global marketplace for petroleum is really, really complicated – but like most economics, it boils down to supply and demand. “You may have demand issues where demand surges because of a strong economy [and] people heading out for the long weekends,” informs Dan. “You may also see a supply issue, in which supply could be abundant – in which case prices fall, or supply is scarce.” For instance, there are two planned interruptions every year – in the early spring when refineries switch from the winter mix to the summer mix; and in late fall when they switch back. We mean, you’d rinse out your blender between smoothies and margaritas, too, right? That makes sense to us!
Now that you know why gas prices are rising, do what you can to use less gas by comparison shopping. Dan suggests the GasBuddy app for that. Also, know the best day of the week to fill up – Mondays and Tuesdays are best in most markets.