A strong economy helped encourage many Americans to buy new vehicles despite the wintry weather and a government shutdown in January.

Nissan and Toyota posted sales declines, but Fiat Chrysler, Honda, Hyundai, Kia and Subaru notched increases.

Analysts estimated that January auto sales rose slightly, compared with a year earlier, despite the polar vortex that froze the Midwest and the shutdown that left many federal workers without paychecks for the month.

Analysts at car-buying advice site Edmunds and Kelley Blue Book parent company Cox Automotive estimated that sales increased 1.3 percent and 0.2 percent, respectively.

“January’s sales strength shows car shoppers are still feeling optimistic, even in the midst of the government shutdown and talk of a slowing economy,” wrote Jeremy Acevedo, Edmunds’ manager of industry analysis. “But despite this positive start, January is such a slow sales month that it doesn’t carry much weight when it comes to predicting the health of the auto market for the full year.”

Henio Arcangeli Jr., senior vice president of the American Honda Automobile Division, said the bad weather had only a temporary effect.

"Before the heavy storms hit, particularly in the Midwest and the East Coast, we were having a very, very strong month of January. We still ended up strong, but it could have been much stronger had the weather cooperated," Arcangeli said. "We believe a lot of that business will come to fruition in February as people postponed a purchase."

With General Motors and Ford having shifted to reporting their sales on a quarterly basis, it's getting harder to accurately gauge the industry's performance from month to month.

But some trends are clear. For one, the average price of a new vehicle continues to rise, in part because of the SUV boom and in part because Tesla's emergence as a major electric-vehicle seller has nudged up the overall average.

Prices averaged $37,149 in January, up 4.2 percent from a year earlier, according to Kelley Blue Book.

Although new-car buyers are in good financial shape right now, they are facing higher interest rates. January's auto loan rate of 6.19 percent was the second-highest monthly rate of the last 10 years, according to Edmunds.

After incentives and a downpayment, the average buyer borrowed $31,707 in January. Their average loan term was 69.1 months with an average payment of $551.

Here's how the major automakers fared for the month, compared with a year earlier:

GM

Edmunds forecast: -2.6 percent
Cox Automotive forecast: -6.8 percent
Actual results: GM no longer reports sales on a monthly basis.

Ford Motor

Edmunds forecast: 11.5 percent
Cox Automotive forecast: -3.4 percent
Actual results: Ford no longer reports sales on a monthly basis.

Fiat Chrysler

Edmunds forecast: 2.9 percent
Cox Automotive forecast: 9.2 percent
Actual results: 2.5 percent (136,082 vehicles)

Fiat Chrysler's Jeep brand, which was red hot in 2018, cooled off a bit in January with a 2.2 percent sales decline.

The Ram truck and van brand jumped 23.8 percent. The Chrysler, Dodge, Fiat and Alfa Romeo brands posted declines of 14.5 percent, 1.9 percent, 1.6 percent and 30.2 percent, respectively.

Toyota

Edmunds forecast: -2.4 percent
Cox Automotive forecast: -4.2 percent
Actual results: -6.6 percent (156,021 vehicles)

Toyota's namesake brand fell 7.1 percent, while its luxury Lexus lineup declined 2.8 percent.

Sales of Toyota's SUVs, crossovers and pickups posted a decline of 7.3 percent -- which is atypical in an industry dominated by larger vehicles. Sales of the company's passenger cars fell 5.5 percent.

Honda

Edmunds forecast: 6.3 percent
Cox Automotive forecast: 0.4 percent
Actual results: 1.5 percent (106,139 vehicles)

The company's namesake Honda brand recorded a sales increase of 0.8 percent, while the luxury Acura brand increased 9.6 percent. Honda's sales of SUVs, crossovers and pickups rose 4.3 percent, lifting the automaker to an overall uptick.

Car sales declined 1.7 percent. Honda continues to sell vehicles only to retail customers, which has preserved resale values but also led to some sales challenges in 2018.

But the company claimed that in 2018, Honda was the best-selling brand for retail passenger cars in the U.S.

Nissan

Edmunds forecast: -15.2 percent
Cox Automotive forecast: -11 percent
Actual results: -18.5 percent (100,741 vehicles)

Nissan sales plunged by double digits for the fifth time in the last seven months. The company's namesake brand declined 19.9 percent, while its luxury Infiniti lineup fell 3.1 percent.

The company's most popular model, the Nissan Rogue crossover, plummeted 27.8 percent to 26,113.

Hyundai-Kia

Edmunds forecast: 6.9 percent
Cox Automotive forecast: 4.1 percent
Actual results: Hyundai sales rose 2.9 percent to 40,796. Kia sales rose 4.9 percent to 37,376

Volkswagen Group

Edmunds forecast: -8 percent (does not include Porsche)
Cox Automotive forecast: 4.4 percent
Actual results: Not yet available.

Subaru

Edmunds forecast: (not provided)
Cox Automotive forecast: 8.2 percent
Actual results: 3.9 percent (46,072 vehicles)

Subaru recorded its 86th consecutive month of sales growth and its best-ever January. The Forester SUV surged 22.8 percent to 13,318, supplanting the Outback as the month's best seller for the brand.

Tesla

Edmunds forecast: 17,167 vehicles (year over year comparison not provided)
Cox Automotive forecast: (not provided)
Actual results: Like GM and Ford, Tesla reports vehicle sales on a quarterly basis.

Follow USA TODAY reporter Nathan Bomey on Twitter @NathanBomey.

This article originally appeared on USA TODAY: Toyota, Nissan sales fall, but Fiat Chrysler, Honda post gains despite polar vortex