[Brian in Oregon]

I don't know about temp changes throughout the day, but the difference is enough that volume/temp compensating devices are being considered by the government.

Soome light reading....

Don’t Pump Gas At Noon: “Hot Gasoline” Costs US Drivers Over $2.3 Billion a Year Blog Archive Alice Hill’s Real Tech News - Independent Tech

NPR : Heat Throws Off Gas Pumps, and Motorists Pay

Flow Meter Tutorial