Vermont is experiencing its worst flooding in decades.
The storm, which veered into Vermont in its final hours, dumped up to 11 inches of rain in some places. At least a dozen towns were surrounded by water and isolated.
Placid little mountain streams turned into roaring brown torrents that smashed buildings, ripped homes from their foundation and washed out roads all across the state.
Emergency Management spokesman Mark Bosma said the helicopters would head to about a dozen towns, including Cavendish, Hancock, Pittsfield, Stockbridge, Strafford and Stratton.
Officials also planned to use heavy-duty National Guard vehicles to reach towns where roads may be passable.
Some Vermont rivers still haven't reached their peak. On Monday, the Otter Creek at Rutland was still more than three feet above flood stage. meteorologist Andrew Loconto said projections are the river won't drop below flood stage until Wednesday.
The storm has been blamed for at least 40 deaths in 11 states. Bodies were pulled from floodwaters and people were electrocuted by downed power lines.
Power is still out to millions on Tuesday, with utilities from North Carolina to Maine reporting well over 2.5 million customers without electricity.
"It's going to take time to recover from a storm of this magnitude," President Barack Obama warned as he promised the government would do everything in its power to help people get back on their feet.
Early estimates put Irene's damage at $7 billion to $10 billion, much smaller than the impact of monster storms such as Hurricane Katrina, which did more than $100 billion in damage. Irene's effects are small compared to the overall U.S. economy, which produces about $14 trillion worth of goods and services every year.
The Associated Press contributed to this report.