The temperature at 10 a.m. was 16 degrees; minus 8 with the wind chill factor. A small band of hooded, gloved, bundled and booted humans was huddled around a statue below the West Front of the U.S. Capitol. Above them, construction of stands for the Ronald Reagan inauguration was underway. Next to them was a piano and a man singing a song: "Thumbs Up, America! We're still a mighty team Thumbs Up, America! Let's wave the star-spangled dream"

This song, "Thumbs Up, America!" was written by former secretary of the Navy J. William Middendorf II, with lyrics by Academy Award-winning songwriter Sammy Cahn, the man who was belting its jolly tune into the frigid air. Cahn will sing the song as part of the inaugural's closing ceremonies, a finale to the four days of events scheduled to greet Reagan's installation as the country's 40th president. It is the inaugural theme song. "Thumbs up, America! We've got the strength, the will Thumbs up, America! The shining city on the hill"

The closing ceremonies start at about 5:30 p.m. on Jan. 20 and will be open to the public. The main feature will be "the most spectacular aerial fireworks show that I, who has been associated with the [fireworks] industry for 20 years, have ever had the pleasure of being part of," said co-producer David Opperman, a spokesman for the fireworks industry. "Coast to coast and hand in hand We're the land heaven smiled upon! Whatever comes up, America Let's bring the drums up, America From * now * on!!!"

More than 4,600 shells will be fired in 15 minutes from five different loca tions along the Mall and around the Washington Monument, Opperman said, this figure scaled down somewhat from the original plan to fire off 10,000 shells. The fireworks will cost $160,000 and will be produced by the Grucci family, well-known artists of the incendiary.

"Sky Salute" chairman John R. (for Reagan) "Tex" McCrary said also that plans to fly an American flag made of 5,000 red, white and blue lights that General Electric had agreed to donate had to be scrapped in order to accommodate television cameras in the helicopter that would have carried the flag.

"The flag would get lost in the smoke, anyhow," McCrary said. "Thumbs up, America! We've only just begun Thumbs up, America! We're still the real number one!"

McCrary said that 100,000 copies of the inaugural theme song will be distributed in "hospitality kits" to people attending the inauguration. "This is one of the great one-man shows," McCrary said after Cahn vamped to a close. "Won't you play us some of your great songs?"

So, Cahn, 67, sat down at the piano and "with cold fingers," started singing "Oh, the weather outside is frightful . . . (Let it snow, let it snow, let it snow)," then segued into "Three Coins in the Fountain," "Saturday Night is the Loneliest Night of the Week," "Time After Time," "Come Fly With Me," "High Hopes" and "Chicago." It was so cold the words came out in clouds. The listeners were thanked for being "brave" enough to come. "Can do, America! Whatever faith may ask Come through, America You're more than equal to the task We can face what must be faced With each other to lean upon Whatever comes up, America Let's bring the drums up, America Because it's thumbs up, America from * now * on!!!"