NEW YORK (MainStreet) — Car insurance rates can vary widely depending on what month you purchase it and start your policy.

The discrepancy among various states can be immense. In 2013, car insurance rates ranged close to 50% in some states depending on the time of year, according to a new report.

Hawaii's 47.9% variance led the nation, followed by Wyoming (39.7%), Washington, D.C. (35.3%) and Maryland (34.8%).

Consumers should always consider shopping around for a better deal, said Laura Adams, a senior analyst at has put together a helpful rate trend calculator that shows consumers how rates are trending in their local area.

The smallest differences were observed in South Dakota at 1.9%, Arkansas with 3.7%, Utah at 4.4% and Iowa with 4.9%. Nationally, car insurance rates ranged 7.5% from the cheapest month in December to the most expensive in March.

"All of this illustrates why it's so important for consumers to regularly shop for car insurance," said Adams. "For example, while December was the cheapest month nationally, it was actually the most expensive in 11 states. You won't know whether you're getting a good deal unless you compare at least three different quotes."

While the research did not reveal any discernible patterns or pinpoint any particular factors, part of the discrepancy stems from the fact that each state regulates insurance differently, she said.

"We didn't really see any patterns that really made a strong hypothesis, but we will continue to watch rates and get a firm analysis," Adams said.

Another factor that could contribute to the difference in rates is the varying demographics and geography. Some states experience more natural disasters than others, which could increase rates.

Other states have more competition among insurance carriers, which lowers rates immensely. The insurance commissioner in South Dakota believes the high competition among carriers writing policies keeps prices generally very low, Adams said.

"The average consumer has no idea it varies so much from month to month," Adams said. "We wanted to make sure consumers do understand rates and the marketplace are not static. They need to be shopping around."

Consumers should shop around for their car insurance at least once or twice a year, she said.

Geography even plays a factor for rental car insurance, especially during holiday weekends and the summer season, said Stephen Ebbett, CEO of, an insurance company.

--Written by Ellen Chang for MainStreet