The weather outside is frightful and, three weeks ago, the same word would have described the New York Rangers and Washington Capitals. Tonight's meeting of the Patrick Division rivals at Capital Centre, however, can correctly be termed a clash between the hottest teams in the National Hockey League.

Each owns a four-game winning streak; the Rangers are undefeated in seven games, the Capitals in five.

The teams have prospered in similar fashion, through defensive responsibility and solid goaltending.

The Rangers are the third highest-scoring team in the NHL behind Calgary and Edmonton, but it was not until they adjusted their defensive thinking that they began putting some victories on the board. During the seven-game unbeaten stretch, they have outscored the opposition, 33-15.

"Their better players are playing better, they're using {goalie John} Vanbiesbrouck as a regular diet, Tomas Sandstrom is back and they're moving the puck better," said Washington Coach Bryan Murray. "But the big thing is that they're playing better defense. They're more sound positionally."

New York winger John Ogrodnick, often accused of forgetting defense when he played for Detroit and Quebec, said, "We haven't really changed our style, but we're all thinking of making sure we have the third guy high and not giving up a three-on-two. We were too loose out there earlier."

The Capitals have dropped only one of their last 10 games, while permitting a total of 20 goals. That stingy attitude has carried them to the top in the Jennings Trophy race with an average yield of 3.00 goals per game. Montreal, last year's Jennings winner, is next at 3.07.

Washington has received strong goaltending from Pete Peeters, who leads the NHL at 2.23, and Clint Malarchuk, who replaced the injured Peeters six games ago and has played so well Peeters cannot get his starting role back.

The return of Rod Langway, along with the continuing dominant play of Scott Stevens and improvement by Larry Murphy and Kevin Hatcher, gives the Capitals probably the strongest backline in the league.

Nevertheless, defense is a team concept and the principal reason the Capitals have lopped 36 goals off their yield compared with this point last season is the responsible play of the forwards, notably Bengt Gustafsson.

"A lot of our success has been due to the way we're playing in the offensive zone," Murray said.

"We're trying to be very disciplined, rotate the puck and concentrate on positional play. The third man is ready to come back and help and we haven't given up many breaks the last 10 or 12 games.

"Bengt Gustafsson is our top defensive center. We're using him on faceoffs, he kills penalties and he plays against top players. He anticipates well, he's a strong guy and he skates well. He likes to play defense and I really think he'd rather play defense than score goals."

Over the last nine games, despite increased ice time, Gustafsson has not been caught for an equal-strength goal by the opposition and he has taken over the club's plus-minus lead with a rating of plus-nine.

During the same stretch, Gustafsson has scored four goals, two of them shorthanded, and has helped Washington kill off 47 of 52 opposing power plays.

That will be an important factor tonight, because the Rangers lead the NHL in power-play goals with 68. It also will be prominent in pregame conversation.

"When we started to turn things around, one of the things we talked about a lot was killing penalties," Gustafsson said.

"Now, before every game, we talk about what the other team is doing. We want to be sure we're all doing the same thing, not having different guys thinking in different directions."

Of his ability to adapt to transition play, which may be unmatched in hockey, Gustafsson said, "It just happens. It's my way of playing. As soon as I see something develop, where we might lose the puck, I just react."

Linemate Mike Gartner has learned to appreciate Gustafsson's reactions. "Gus is a very intelligent player; that's his biggest asset," Gartner said. "He has good anticipation offensively and defensively. Playing with Gus, I know I can take a few more chances, because he'll cover up for me."

Capitals Notes:

The Capitals shipped right wing Ed Kastelic to Binghamton yesterday, officially for two weeks of conditioning. Kastelic, who had not played since Dec. 26, was scoreless in 24 games while collecting 50 penalty minutes . . . The Rangers, hit by a flu bug, summoned right wing Chris Jensen from Colorado for tonight's game . . . This is the fourth time a team has carried a long undefeated string into Capital Centre this season. In each previous case, the visitor extended the streak, then lost its next game: Calgary won, 5-4, to reach nine; St. Louis tied, 1-1, to hit seven, and Philadelphia won, 3-2, for a season high of 14 . . . The Rangers flew in yesterday to avoid the snow. Rangers officials have not forgotten an embarrassing postponement here on March 3, 1978, when a two-inch morning snowfall that created panic had disappeared by game time.