Just sign up for Gasbuddy.com
It will keep you updated to the price swings. Just use their "heat map
" which is colored coded map as far as prices Red's = highest prices and Green's = lower prices. You can zoom down to check out individually stations, or just a region.
Before I start a trip, be it 50 miles or 500 miles, I'll check on Gasbuddy to see pockets of cheaper fuel prices, especially jumping between states.
Here in Northern Ohio diesel will range between $4.09 and $4.49. Diesel prices tend to not move as much, where as regular gas is all over the place. In the last 6 months it has been at a low of $3.09 to $3.79 ten days ago. Some days it will go up 35 cents, and drop a few pennies every two days...then go up again in one shot 20 cents. Worried what summertime prices will be. Here is a 11 year chart on the price of gas.. Gasbuddy 11 year price chart
I also use the phone app. for gasbuddy.