Seasonal electric rates: why the price changes in June and October

Why summer costs more to supply

In most of the country, the electricity system peaks in summer. Air conditioning is the largest single load on the grid on a hot afternoon, and it runs in every building at once. Meeting that requires power plants that sit idle the rest of the year and wires sized for a few hundred hours of use. A seasonal rate charges more in the months when that capacity is being used and less when it is not, which is closer to the real cost than a single year-round price. In the coldest states, where electric heating dominates, the pattern flips and the winter rate is the higher one.

The four ways a tariff can be seasonal

• Different energy rates. The simplest: 16¢ in summer, 13¢ in winter, same hours. The bill shows one rate at a time, so the change looks like a rate increase.
• Different peak hours. A time-of-use plan with a 2pm-to-7pm peak in summer and a 6am-to-9am plus 5pm-to-8pm peak in winter. Same rates, different hours. Habits that worked in July are wrong in January.
• Different tier allowances. A tiered plan whose first block is larger in summer to allow for cooling, or larger in winter for heating. The cliff moves with the season.
• No peak in one season. Some plans have a peak only in summer and charge a flat rate the rest of the year. The winter grid on those plans is one colour.

When the seasons change

The switch is applied by billing period, and a period that spans the change is prorated: eighteen days at the winter rate, twelve at summer. That bill is legitimately hard to read. The one after it is the first clean summer bill, and the one that usually prompts the question.

Reading it off the grid

Every rate page on this site draws the plan as twelve rows of hours, one per month. A seasonal plan shows a visible change at the boundary: the peak block appears, moves, or changes colour in June and reverts in October. The annual cost table underneath is computed month by month, so the summer rate is already in it. And the seasonal spread — how much the same house costs in July versus February — is written out in the plan’s notes when it is large enough to matter.

What to do about it

Not much about the rate itself; the season is the season. But two things follow from knowing the dates. The first is budgeting against the summer figure rather than the annual average, which is the difference between a summer bill that is expected and one that is a shock. The second is that plan comparisons change with the season: a plan with a low winter rate and a high summer rate suits a house with gas heat and a small air conditioner, and punishes one with central air. The calculator on each utility page prices the whole year, so the seasonal trade-off is already in the number.