While Iowa had about twice as much rain as usual last month, the warm weather will arrive soon, forcing us to switch on power-sucking air conditioners. It’ll be a drain on electricity, but nothing the utilities can’t handle and nothing like the rolling blackouts of California.Alliant Energy spokesman John Ruff says the Duane Arnold power plant near Cedar Rapids was off-line during May but is back on-line now. Ruff says the utility has access to plenty of power to make it through the summer heat, but he urges customers to conserve electricity when they can.Once the warm weather arrives, Ruff says keeping the thermostat a few degrees higher can translate to several dollars off the utility bill.Ruff predicts the peak demand will rise about two percent this summer from last year, but Alliant has a reserve margin of 17-percent available to meet demands.