About 35 people have now been killed in winter storms that have struck the US, mainly in central states.
Ice storms occur when rain falls in temperatures so low it freezes
A state of emergency has been declared and the National Guard called out in Missouri after the storms knocked out power to 200,000 homes.
President George W Bush has released federal aid for some affected states.
Weather forecasters say the storm system will head north-east, threatening to bring more than a foot (30cm) of snow to New England.
Central states were struck by ice storms - when rain falls during very low temperatures, causing it to freeze almost instantly as it hits a surface, resulting in ice layers sometimes several inches thick.
Citrus fruit struck
The extreme weather downed trees, traffic lights and power lines and blocked roads in Missouri and Oklahoma, where most of the deaths occurred.
Other fatalities were in Iowa, Texas, New York and Maine.
President Bush declared an emergency in Oklahoma.
There, about 350 national guardsmen went door-to-door to check on residents in the hardest-hit areas, and helped to clear icy roads of branches and power lines.
In Texas, 160 flights were cancelled on Monday at Dallas-Fort Worth International Airport, adding to the 415 on Sunday.
Record-breaking cold weather even hit California, which usually has mild temperatures year-round.
Citrus fruit growers in parts of the state are using wind machines to protect their fruit from frost damage.
The National Weather Service said it was "a very, very big cold front".
It said the storm is gathering moisture from the Gulf of Mexico and cold air from the Arctic, and is expected to hit the east coast on Tuesday.
The freezing rain was so bad, I couldn't open my car door this morning, so I had to take my bicycle to the train station.
Rafael Winterpacht, Chicago, IL
On Saturday morning at 0730, the temperature was -13 degrees Celsius. Our house pipes have been freezing overnight and we have been going without water until the sun heats them up again.
Norman, Palmdale, CA, USA
We woke up this morning to several inches of snow mixed with ice. Leaving for work, the neighbours mentioned there have been over 170 traffic accidents since midnight, so we are both working from home today.
Amber, Toronto, ON
It has been so bad in Colorado and nobody has helped us. Cattle are still dying and there's no help from anyone. I have been wiped out -my cattle are dead. Everyone worries about the cities - better start worrying about where your food comes from and remember, when the beef costs so much, someone should have helped us farmers.
Peggy Otto, SE Colorado
I woke this morning to downed trees all over my yard. The ice is so thick that I barely touched the gas peddle and my car slid all the way down my drive way. It's very treacherous out there. Not many people are out on the roads or freeways. Most freeways into the city have been closed due to the ice storm.
Thiago, Dallas Texas
I am in Illinois and this storm has knocked out the power, which has since been put back on. We have had three inches of ice dangling off power lines, trees. Our car doors are frozen shut. Temperatures are around -10C at times. Hopefully everyone else south of us will get their power back soon and hopefully everyone else stays safe.
Gareth Hale, Illinois, USA
It may look like the storm is only over the Midwestern states but, I tell you, we are definitely feeling it here in Yuma, Arizona, too. We are used to being one of the hottest places in the U.S. and this is colder than we can remember. The temperatures have dropped here and it's enough to even snow, which is really something. People bundled up in thick jackets and wearing scarves, earmuffs and gloves in the desert southwest here at the Mexican-American border? Wow.
Michelle Wheaton, Yuma, Arizona U.S.A
Here in tiny Flint, Texas (population 242) the temperatures are plummeting and we are bracing for the next attacks of nature. So far the weather system that has produced ice storms to our north and west has caused a deluge that showed as eight inches of rainfall in the last 48 hours. Roads are flooded and the sheer soaking of the earth is causing trees to topple in the high winds that are part of this system. At home, perched on a ridge above the acres of trees on my land, I watched as two sixty-foot-tall pine trees simply lost their grip on the sodden soil and crashed to earth. A tiny creek, which often dries out during the summer month and meanders thru the middle of my property has overflowed its banks and turned the surrounding land into a quagmire. Another, larger, creek which delineates the further boundary of my land has been transformed into a raging flood. Watching the local TV weather the moving front is dramatic. Twenty miles to the northwest the temperatures are below freezing while twenty miles to the south east it's 70F as the warm gulf air battles the encroaching Artic attack.
Eric Rathbone, Flint Texas USA