The prices are smoothed out in the
futures markets. You can buy a barrel of heating oil for next heating season, today, at a lower price than you can buy oil for right now. So if something happens in July that will increase the price, the price to the end consumer will rise based on more than just supply, and won't just fall back down either; it'll crawl back down. Speculators buy futures based on everything that drives any market, including fear and uncertainty.
The prices do go up due to greater demand, but reporters don't understand the futures markets, so they don't mention it and people can only assume hidden causes for inexplicable price increases and slow decreases. (Such as greed, which exists in all markets.)