Gas prices for eight of Illinois’ 9 major utilities are higher, compared with a year ago, led by Liberty Utilities, which is charging a supply price that is about 63 percent higher; Nicor Gas and Mt. Carmel, both charging a price about 56 percent higher; Peoples Gas, which has a price about 28 percent higher; and MidAmerican Energy, with a price about 27 percent higher, according to CUB’s review of December gas prices.
Gas prices have been elevated because of colder-than-normal weather last winter and record gas exports (meaning profit-hungry companies sending gas outside the United States) increasing demand and tightening supply. The Energy Information Administration, predicts that prices will rise this winter, but factors such as milder weather are expected to lead to lower increases than previously expected.
Market conditions impact the prices individual consumers pay to heat their homes. Gas utilities file supply prices–called the Purchased Gas Adjustment (PGA)–each month with the Illinois Commerce Commission (ICC). Here’s what CUB found in our review of prices in December.
- Compared with November, five utilities have higher rates: Consumers Gas (about 19 percent higher ), Illinois Gas (about 1 percent), MidAmerican (14 percent), North Shore Gas (17 percent), and Peoples Gas (18 percent). Three charged prices that were lower: Ameren Illinois (about 5 percent lower), Liberty Utilities (about 2 percent), and Mt. Carmel (about 13 percent). One utility, Nicor Gas, had the same price as in November.
- Compared with December 2024, this month’s prices were higher for eight utilities, ranging from about 10 percent higher for Illinois Gas to about 63 percent higher for Liberty Utilities. Only one utility was less than last December, with Ameren Gas at about 3 percent lower. See all December prices below.
December Gas Prices
Ameren Illinois– 44.07 cents per therm (DOWN about 3 percent from December 2024)
Consumers Gas– 48.91 cents per therm (UP about 17 percent from December 2024)
Illinois Gas– 49.23 cents per therm (UP about 10 percent from December 2024)
Liberty Utilities– 40.70 cents per therm (UP about 63 percent from December 2024)
MidAmerican Energy– 67.31 cents per therm (UP about 27 percent from December 2024)
Mt. Carmel– 66.25 cents per therm (UP about 56 percent from December 2024)
Nicor Gas– 39.00 cents per therm (UP about 56 percent from December 2024)
North Shore Gas– 51.53 cents per therm (UP about 15 from December 2024)
Peoples Gas– 40.63 cents per therm (UP about 28 percent from December 2024)
Note: Your utility is determined by where you live, so you cannot switch from one utility to another. Under Illinois law, gas utilities are not allowed to profit off supply prices—they pass those costs from gas producers and marketers onto customers with no markup. State regulators annually review the utilities’ gas-management procedures to evaluate whether the companies did a reasonable job with their gas purchases, given market conditions, to hold down costs for consumers as much as possible. Regulators can order refunds, although that is rare.
A few tips from CUB:
- Keep the lines of communication open with your utility. If you are having trouble affording your gas bills, it is vital that you contact your utility. Ask if you qualify for any energy assistance programs; see if you can set up a plan that gives you more time to pay off your bills; and inquire about no or low-cost energy efficiency programs the company offers.
- Practice energy efficiency at home. For tips and information about helpful energy efficiency programs offered by your utility, visit CUB’s Clean Energy page.
- Beware of alternative supplier rip-offs. If a deal seems too good to be true, there’s a good chance it is. If the utility supply price increases, remember that it’s due to market factors that also will increase alternative supplier prices. As volatile as gas utility prices are, your best bet for gas supply is likely with your utility and not with an alternative supplier. Read our tips. (Note: Only consumers in Northern Illinois have gas choice.)
- See if you qualify for energy assistance. To apply or learn more about the Low Income Home Energy Assistance Program (LIHEAP), visit this state of Illinois webpage. (Also, check out our Step by step guide to applying for LIHEAP.)
- More helpful resources:
- CUB’s Gas page
- Historical gas prices
- CUB’s gas-price reports from 2024: January, February, March, April, May, June, July, August, September, October, November and December. And 2025: January, February, March, April, May, June, July, August, September, October, and November.
- If you want to consider moving away from gas, visit our electrification page and order CUB’s free Better Heat Guide to learn how to make the transition to more efficient appliances, like electric heat pumps and induction stove tops.
