The highs and lows are the same spot for electricity...highest in summer, and cheapest in winter.
Electricity, they can turn down the power stations to 30-40% of peak production (or turn them off), so the curve is there, but reasonably flat.
Gas doesn't have the turndown, so they have to cheapen prices to encourage discretionary users to use it. Higher prices in peak demand times lad the discretionary users to cut back some, and helps fund new wells/plants/imports.
Oz is in a strange case at the present time, with all of the gas fields in Queensland coming on to meet their future export contracts, and flooding the market from time to time.
Spot market gas WAS $4.40/GJ (Oz, so roughly translates to $4US/1000cuft) a year ago, and is scheduled to go to $10 when the export market kicks in, which will be the death knell for most gas fired power stations in Oz.
However in the interim, there are days that it drops to 50c as new wells come in, and liquification plants come on line.
As this happens, the 30 year old semi mothballed turbines come in and burn the cheap gas for a profit, making the glut go away.