Washington: Today - Cloudy, high near 40s, low in the upper 20s. Snow is possible tonight. Wind will be from the north at near 10 mph. The chance of precipitation is 20 percent today and 60 percent tonight. Saturday - Snow likely, high in the mid 30s.

Maryland and Virginia: Today - cloudy, highs from the 30s to the mid 40s, lows from the 20s to the mid 30s. Snow is possible tonight. Saturday - Snow likely, highs in the 30s. There is a chance of rain in lieu of snow in southwestern Virginia.

Lower Potomac and Chesapeaka Bay: Today - Cloudy with snow possible by tonight. Wind will be from the north at from 10 to 15 knots today becoming variable tonight. Waves in ice-free waters will be near 1 foot.Visibility will be more than 5 miles - except less than 1 miless than 1 mile in snow.

Extended Area Forecast for Sunday through Tuesday: Fair through the period. Snow is possible in western Virginia. Highs will be from the low 30s to near 40s, lows from the teens to the 20s. Normal Washington temperatures for the period are a high of 47 and a low of 29.

West Virginia: Today - Cloudy with snow flurries possible. Highs will be from the mid 20s to the mid 30s, lows from the teens to the low 20s. Saturday - Snow flurries possible over most of the state, highs from the mid 20s to the low 30s.

Almanac Data for today - Sun rises 6:57 a.m., sets 5:48 p.m.; moon rises 1:16 p.m., sets 2:59 a.m.; Tides: high 3:37 a.m. and 4:04 p.m., low 10:25 a.m. and 11:02 p.m. High and low tides at the following locations may be obtained by substraction the hours indicated from the tides above. Annapolis (1 1/2), Bloody Point Lighthouse (4 1/2), Deale, Md. (4 1/2), Colonial Beach (6), Norfolk (1 1/2), Virginia Beach (1), Solomons Island (6 1/2), Point Lookout (7).

The Council of Governments' Air Quality Index for yesterday showed the high reading in the Walshington area during the 2 p.m. to 3 p.m. period was 19 for the pollutant, particulate matter. Index values between zero and 24 indicate good air quality. When the index exceeds 100 the air is considered very unhealthy and individuals with lung, heart and eye aliments are urged to restrict their activity. The forecast for today indicates that the air quality will be fair.

The National Weather Service forecasts the Potomac River stage at Little Falls should be near 3.4 feet today.

Washington data at 7 p.m. (EST) yesterday: Highest temperature since 7 a.m. yesterday, 41 degrees at 1:40 p.m. Lowest temperature since midnight, 29 degrees at 12:05 a.m. Deficiency of temperature since Feb. 1 109 degrees. Deficiency of temperatures since Jan. 1, 199 degrees. Record high temperature for today, 79 degrees in 1976. Record low temperature for today, 5 degrees in 1958. Relative humidity: Maximum, 85 per cent at 2 p.m. 24 hour precipitation, .01 inceses. Deficiency of precipitation since Feb. 1, .9 inches. Excess of precipitation since Jan. 1, 3.59 inches. Highest observed wind since 7 a.m., 13 miles per hour from the south at 3:52. Peak gust since 7 a.m., 14 miles per hour from the south at 3:17 p.m.(TABLE) Time(COLUMN)T.(COLUMN)H. 12 midnight(COLUMN)30(COLUMN)63 1 a.m.(COLUMN)30(COLUMN)66 2 a.m.(COLUMN)31(COLUMN)61 3 a.m.(COLUMN)31(COLUMN)61 4 a.m.(COLUMN)31(COLUMN)69 5 a.m.(COLUMN)31(COLUMN)69 6 a.m.(COLUMN)31(COLUMN)69 7 a.m.(COLUMN)32(COLUMN)66 8 a.m.(COLUMN)33(COLUMN)67 9 a.m.(COLUMN)34(COLUMN)67 10 a.m.(COLUMN)36(COLUMN)62 11 a.m.(COLUMN)37(COLUMN)57 12 noon(COLUMN)40(COLUMN)53 1 p.m.(COLUMN)40(COLUMN)53 2 p.m.(COLUMN)41(COLUMN)51 3 p.m.(COLUMN)4 p.m.(COLUMN)37 76 5 p.m.(COLUMN)35(COLUMN)85 6 p.m.(COLUMN)35(COLUMN)85 7 p.m.(COLUMN)35(COLUMN)85(END TABLE) Temperature ending 8 a.m. (EST) yesterday:(TABLE) City(COLUMN)H.(COLUMN)L. Albany(COLUMN)29(COLUMN)4 Albuquerque(COLUMN)34(COLUMN)30 Amarillo(COLUMN)27(COLUMN)25 Anchorage(COLUMN)35(COLUMN)18 Asheville(COLUMN)51(COLUMN)33 Atlanta(COLUMN)56(COLUMN)41 Atlantic City(COLUMN)32(COLUMN)9 Austin(COLUMN)45(COLUMN)39 Baltimore(COLUMN)38(COLUMN)21 Billings(COLUMN)18(COLUMN)1 Birmingham(COLUMN)51(COLUMN)39 Bismarck(COLUMN)16(COLUMN)-5 Boise(COLUMN)37(COLUMN)17 Boston(COLUMN)39(COLUMN)24 Brownsville(COLUMN)69(COLUMN)47 Buffalo(COLUMN)23(COLUMN)10 Burlington(COLUMN)21(COLUMN)-7 Casper(COLUMN)26(COLUMN)6 Charleston, S.C.(COLUMN)50(COLUMN)46 Charleston, W.V.(COLUMN)33(COLUMN)25 Charlotte(COLUMN)51(COLUMN)40 Cheyenne(COLUMN)30(COLUMN)13 Chicago(COLUMN)23(COLUMN)1 Cincinnati(COLUMN)27(COLUMN)23 Cleveland(COLUMN)25(COLUMN)15 Columbia, S.C.(COLUMN)55(COLUMN)39 Columbus(COLUMN)23(COLUMN)20 Dal.-Ft. Worth(COLUMN)36(COLUMN)33 Dayton(COLUMN)26(COLUMN)20 Denver(COLUMN)38(COLUMN)21 Des Moines(COLUMN)15(COLUMN)-7 Detroit(COLUMN)27(COLUMN)21 Duluth(COLUMN)18(COLUMN)2 El Paso(COLUMN)54(COLUMN)38 Fairbanks(COLUMN)14(COLUMN)-10 Fargo(COLUMN)8(COLUMN)-5 Flagstaff(COLUMN)35(COLUMN)16 Great Falls(COLUMN)11(COLUMN)-5 Hartford(COLUMN)37(COLUMN)8 Helena(COLUMN)19(COLUMN)12 Honolulu(COLUMN)84(COLUMN)73 Houston(COLUMN)45(COLUMN)32 Indianapolis(COLUMN)30(COLUMN)24 Jackson, Miss.(COLUMN)50(COLUMN)31 Jacksonville(COLUMN)61(COLUMN)44 Juneau(COLUMN)41(COLUMN)31 Kansas City(COLUMN)19(COLUMN)8 Las Vegas(COLUMN)58(COLUMN)41 Little Rock(COLUMN)34(COLUMN)31 Los Angeles(COLUMN)63(COLUMN)44 Louisville(COLUMN)33(COLUMN)29 Memphis(COLUMN)41(COLUMN)35 Miami Beach(COLUMN)75(COLUMN)70 Midland-Odessa(COLUMN)47(COLUMN)33 Milwaukee(COLUMN)18(COLUMN)4 Mois-St. Paul(COLUMN)16(COLUMN)-1 Nashville(COLUMN)40(COLUMN)30 New Orleans(COLUMN)47(COLUMN)39 New York(COLUMN)34(COLUMN)22 Norfolk(COLUMN)38(COLUMN)26 North Platte(COLUMN)14(COLUMN)-11 Oklahoma City(COLUMN)31(COLUMN)25 Omaha(COLUMN)18(COLUMN)-7 Orlando(COLUMN)72(COLUMN)54 Philadelphia(COLUMN)31(COLUMN)9 Phoenix(COLUMN)61(COLUMN)47 Pittsburgh(COLUMN)30(COLUMN)23 Portland, Maine(COLUMN)24(COLUMN)23 Portland, Ore.(COLUMN)49(COLUMN)34 Providence(COLUMN)37(COLUMN)14 Raleigh(COLUMN)50(COLUMN)29 Rapid City(COLUMN)14(COLUMN)0 Reno(COLUMN)42(COLUMN)22 Richmond(COLUMN)44(COLUMN)25 St. Louis(COLUMN)27(COLUMN)13 St. Prbg.-Tampa(COLUMN)65(COLUMN)53 Salt Lake City(COLUMN)39(COLUMN)29 San Antonio(COLUMN)47(COLUMN)42 San Diego(COLUMN)63(COLUMN)55 San Francisco(COLUMN)59(COLUMN)49 San Juan(COLUMN)86(COLUMN)68 St. Ste. Marie(COLUMN)23(COLUMN)6 Seattle(COLUMN)47(COLUMN)38 Shreveport(COLUMN)43(COLUMN)34 Sioux Falls(COLUMN)12(COLUMN)-8 Spokane(COLUMN)38(COLUMN)31 Syracuse(COLUMN)27(COLUMN)4 Topeka(COLUMN)23(COLUMN)-2 Tucson(COLUMN)57(COLUMN)40 Tulsa(COLUMN)31(COLUMN)23 Washington(COLUMN)41(COLUMN)39 Wichita(COLUMN)25(COLUMN)15(END TABLE)