WCBS-TV had as good a February as Dan Jansen, Bonnie Blair and Nancy Kerrigan, skating to an easy sweeps victory in just about every category on the back of the Winter Olympics.The Games always provide a ratings boost for network affiliates, but the Kerrigan-Tonya Harding story, along with Jansen’s and Blair’s successes, provided an even greater lift than usual. Late news was the segment most directly affected by the Olympics, with WCBS leaping 31% to 12.7 rating/25 share, up from last February’s 9.7/19. WABC fell to second at 10.1/18, and WNBC slipped to 9.5/17. Remove the days of Olympic lead-ins and the sweeps tell a different story, however, with WABC back on top at 12.4/23, followed by WNBC (10.6/20), and WCBS (8.9/16). WCBS’ sweeps-inclusive late-news gains helped “Late Show With David Letterman” double last year’s slot average to a 9.0/25, eating into both “The Tonight Show” (down 22%, to a 4.2/11) and “Nightline” (dipping 8% to 6.1/14). There was, however, more to February than just the Olympics. The most fascinating story was WNBC-TV’s 3-6:30 p.m. block. The affil’s “News 4 New York” jumped 30% from last year to an 8.4/15 at 6 p.m. WABC climbed 7% to 11.9/21, while WCBS earned a 6.5/12. That followed the hourlong “Live at Five” newscast, which surged 12% from last year to a 7.6/15 (still second in early news to WABC’s 11.2/22; WCBS was third at 5.9/12). What made the growth there so impressive is that its lead-in, “Donahue,” stumbled 18% from last year’s rating to a weak 4.9/11, getting trounced by both “Oprah” and “Geraldo.” WABC padded its lead by ignoring two blizzards. On Feb. 8 and Feb. 11, when WCBS and WNBC provided newscasts to let viewers know about weather, traffic and transit conditions, WABC stuck with “Oprah,” scoring a 17.6 /30 and 16.8/29, respectively, well above its monthlong 12.1/27 average. “Geraldo” averaged a 6.2 rating during its nine Olympic-day appearances, compared to a 5.3 in its five showings before the Games. Repairing this timeslot is essential for WNBC to capitalize on the 16% gain scored by “Sally Jessy Raphael” (7.4/19) over what “Maury Povich” earned there last February. WWOR’s “Ricki Lake” earned a 5.9/12 at 5 p.m. to handily beat “Montel Williams” (4.6/9) on WNYW; at noon, “Ricki” repeats did even better, scoring a 6 .7/19, more than tripling WNYW’s anemic “Fox News at Noon” (2.1/6) and “Good Day Street Talk” (1.9/6). WPIX did make small inroads at noon and received good news in prime access, where a double run of “Family Matters” averaged 9.1/14, a 65% improvement over “A Different World” and “Murphy Brown” a year ago. That raised WPIX from last place to less than 0.1 rating point behind WCBS for second.