The Federal Reserve should take note of recent earnings results from railroad operators Union Pacific and Norfolk Southern ahead of its next interest rate hike, CNBC's Jim Cramer said Monday as stocks sold off.

"See, the rails are a terrific proxy for commerce in America, and after listening to the conference calls last week from Union Pacific and Norfolk Southern, my feeling is that we still have a very strong economy," he said on "Mad Money."

"However, our economy also seems to be decelerating just enough to keep the Federal Reserve from hitting us with another rate hike anytime soon," Cramer warned.

On the surface, both companies' results were strong, topping analyst expectations and showing notable bright spots in the business.

But when it comes to the Fed, whose Open Market Committee will meet this Tuesday and Wednesday to decide on next steps for interest rates, the results weren't so clear-cut, Cramer said.

"Neither company saw a sudden fall-off in [its] business, but — and this is a big but — they both saw a deceleration in the growth of some key economically sensitive cargoes versus previous quarters," he explained. "Plus, at least in the case of Union Pacific, a lot of business was pulled forward as companies raced to beat the increase in tariffs on imports from China."

And because Fed officials should consider the whole economic picture when deciding whether to raise short-term interest rates, it's worth taking note of these imbalances, the "Mad Money" host argued.

For example, one of the railroad operators' main sources of strength came from intermodal, a business that involves using several different modes of transportation to ship goods. Increased e-commerce and the U.S. truck driver shortage aided in the strength.

"However, Norfolk Southern noted that the trucking shortage was beginning to abate as the year ended," a "warning sign" for Norfolk and other railroads, whose intermodal businesses often compete with trucking companies, Cramer said.

Both companies also saw strength in chemical cargo shipments, and Union Pacific generated 19 percent growth in the energy, construction and manufacturing markets.

However, points of nascent weakness remained: vehicles, typically a healthy business for the railroads, saw "no growth whatsoever, with neither company expecting much of an increase" in business, Cramer noted. Agriculture, "almost always a bright spot," also took a hit because of a lack of Chinese demand for U.S. soybeans, he said.

And while the headline strength might encourage some investors, Cramer warned that part of the strength was "likely an artificial spike" tied to worries about higher tariffs coming due in 2019.

"Put it all together and the rails paint a picture that's consistent with what we're seeing from the rest of the economy: they had a deceleration month to month in the fourth quarter, [with] fear of higher tariffs on Chinese goods causing many orders to be pulled forward. At the same time, Union Pacific and Norfolk Southern delivered fantastic profits without experiencing much wage inflation," the "Mad Money" host said.

"I sure hope Jerome Powell, our wayward Fed Chairman, is looking at these numbers, because they suggest that we really don't need a rate hike here. To the extent the rails had a strong fourth quarter, much of it came from the desire to beat the scheduled increase in tariffs, not from an acceleration in our economy," Cramer continued. "So when Powell holds his press conference on Wednesday, I sure hope he continues to hold off on any talk about the need to tighten."