President Reagan acted against the advice of segments of his administration when he decided last week to sell the nation's weather satellites, according to sources in the administration and Congress.

The administration originally had decided not to sell them and had maintained that position as late as last October, although some government officials say the policy was always in flux.

But at a Cabinet Council meeting last fall, Commerce Secretary Malcolm Baldrige and his deputies argued for and won approval of a policy to sell the satellites. The recommendation then went up the ladder to the president.

The proposal's history began with a drastic 1981 budget cut that threatened to kill off the government's land-sensing satellite (Landsat) program eventually.

To the rescue came the Communications Satellite Corp. (Comsat), which offered to buy Landsat if the government also would sell the weather satellites. Now there is concern that the deal could end up costing the government hundreds of millions of dollars, creating a government-subsidized monopoly and imperiling the quality of U.S. weather studies.

One Commerce Department official said the decision to sell the weather satellites was "a pure, ideological decision," not an economic one. Another said that "none of the government's own reports were obeyed." One congressional expert commented, "The government now has to justify its proposal, when its own studies don't."

As criticism of the sale has mounted, the administration seems to be reconsidering the matter. Though the original announcement spoke of President Reagan's "decision" to sell the satellites, a Commerce Department spokesman now says the administration will "explore further" such a "transfer."

Warnings about the deal's cost and risks came to Baldrige from at least three federal agencies--NASA, the Defense Department and the Landsat Advisory Committee in Baldrige's department, according to documents obtained by The Washington Post.

And a government-commissioned report due next week from the National Academy of Public Administration also warns against sale or "commercialization" of the weather satellites.

The three government reports, which officials at the Office of Management and Budget maintain are advisory only, make these points:

* Several independent estimates show that the proposal would cost the government money, not save it.

* The satellite sale would create a massively subsidized monopoly company.

* Weather forecasting information and future research could suffer because any company that might own the weather satellites may not be willing to spend much on those less profit-making activities.

* Since civilian weather satellites share information with the Defense Department and serve as a backup for defense weather satellites, the sale raises questions of national security.

The tale of the weather satellites begins not with weather-sensing satellites, but with land-sensing satellites.

More than one administration has wanted to turn the government's experiments with those satellites into operating commercial ventures. Viewing land from space can provide invaluable information about such things as mineral deposits and the spread of pests and disease among crops.

Early in the Reagan administration, David A. Stockman and his budget-cutters at OMB forced the issue by eliminating funds for replacement land satellites. The program could die unless it was shifted out of the government, and quickly.

But no company was ready to buy the satellites. No proven market exists for the Landsat data, at least none big enough to pay for launching and maintaining the satellites.

In 1981, Comsat came up with a solution which the company brought privately to the government. It was distasteful to many in the Reagan administration, but it would get land satellites out of the government, keep them alive and possibly give Comsat a big financial boost. Some in OMB even thought it might save the government money if the proper deal could be made.

Comsat offered to buy the land-sensing satellites if the government threw the weather satellites into the deal. The government would guarantee to buy weather data from Comsat for $300 million a year for a decade or more. In addition, it offered to buy the $1.6 billion worth of land and weather satellites for about $315 million. Suddenly the land satellites takeover became attractive and virtually risk-free.

NASA Administrator James M. Beggs told the trade journal Satellite News that the proposal "sounds like a damned good deal for them Comsat but maybe not for the federal government."

Last fall, the government solicited industry comments on the idea of selling the weather satellites. The government reported later, "Of the 14 responses, only two firms supported the policy in principle and only one firm, Comsat, supported the specific stated policy of transfer 'as soon as possible' . . . . "

Now, only months later, the government plans to go back to the companies, this time in the hope that hundreds of millions of dollars per year in possible subsidies might changes the companies' minds and encourage them to make an offer for the satellites, Commerce Department officials said.

They said the proposed sale has been shepherded through the government by Baldrige and two deputy secretaries of Commerce. The case has been in the hands of Deputy Secretary of Commerce Guy Fiske since last summer.

In an interview this week, Fiske acknowledged that the sale could cost the government money for years.

But the prime issue, he said, is not the cost to the government but whether a private company could put up "better satellites" and "create new markets." As for the negative government reports about commercializing the weather satellite, Fiske said they are only "preliminary."

In announcing the president's decision to sell the satellites, Administrator John V. Byrne of the National Oceanographic and Atmospheric Administration said that what made the proposal stick was the administration's belief in corporations. "The private sector is what made America great," Byrne said.

But Deputy OMB Director Joseph Wright said the White House would be "very reluctant" to get into any deal that did not save the government money. Fred Khedouri, associate director of OMB for science issues, said that if it proves true that the deal will cost the government more money, "We will suffer a profound decline in enthusiasm" for the notion.

But the policy remains to try to sell the weather satellites, and OMB officials say they will not know whether there will be a savings or loss until the proposals come in from companies.

In analyzing the proposed sale, NASA and Defense experts reported, "There is considerable financial, policy and program risk to the government in commercializing the weather satellites, and there is no clear policy or financial benefit to be realized."

The panel went on:" A single government-chartered, subsidized firm having the weather satellites would seem antithetical to the underlying economic philosophy of the United States and, in particular, this administration, as we understand it."

Comsat claimed that if the government sold the satellites, the U.S. Treasury could save $1.16 billion over 10 years. The NASA/Defense panel contradicted this. " We estimate the Comsat proposal will . . . in fact cost the government $798 million." Several other agencies informally calculated that the government would lose about $800 million, according to a Commerce official.

Another report, by the Landsat Advisory Committee, said there is only a "small commercial opportunity associated with the weather satellites. Therefore, the weather satellite systems were judged to be inherently governmental."

To make them truly commercial, the report said, the whole National Weather Service would have to be commercialized before a large market for weather data could be created.

Reaction in Congress has been quick. Several hearings have been held or are scheduled, and this week a "sense of the Congress" resolution was passed saying that no sale of government satellites should be considered without first going through Congress.

Rep. James H. Scheuer (D-N.Y.), whose House Science subcommittee on natural resources is expected to hold joint hearings beginning April 13 said,"I have seen nothing so far which persuades me that the weather satellites ought to be commercialized.

"All the reports I have seen without and within the government give no reason the weather satellites ought to be transferred. I will keep an open mind, but the administration just has not made their case yet," he said.