Washington: Today - Occasional rain, high near 40, low in the low 30s. The chance of precipitation is 90 per cent today diminishing to 40 per cent tonight. Sunday - Variable cloudiness with occasional rain, high near 40.

Maryland: Today - Occasional rain with mixed snow and rain on the mountains, high near 40. Sunday - Variable, cloudiness with a chance of rain, highs will range from the 30s in the west to the 40s.

Virgina: Today - Occasional rain, high in the 40s, low in the 30s. Sunday - Variable cloudiness with a chance of rain, high in the 40s.

Lower Potomac and Chesapeake Bay - Rain possibly mixed with wet snow. Winds will be easterly at 8 to 15 knots. Waves will average 1 to 2 feet. Visibility will be less than 1 mile.

West Virginia: Cloudy with occasional rain, high in the 40s, low in the mid 30s. Sunday - Variable cloudiness with a chance of rain, possibly beginning as snow, high in the 40s.

Extended Area Outlook for Monday through Wednesday - Snow and rain Monday with clear skies expected. Tuesday and Wednesday High will be in the low 40s Monday decreasing to the 20s and low 30s by Wednesday. Lows will be in the 20s.

The National Weather Forecast for Today - Very cold temperatures will reach the high Plains portion of Montana, he Dakotas and Nebraska. Snow is likely in a band from the Great Lakes across the central Plains and into the central Rockies. Light snow will extend into the northern Plains and Rockies and from the Great Lakes across central and southern New England. Rain is likely in the central Atlantic states and from the Gulf Coast up the Appalachians to Pennsylvania and the Atlantic Coast. Some fog will occur in the valleys of the Pacific Coast states. Sunny skies will be limited to Florida, the southern Plains, the southwest states, scattered through the West Coast states, the northern portion of the Plains and northern Maine.

Almanac Data for today - 12-13-77. Sun Rises 7:27 a.m., sets 4:56 p.m.; noon rises 11:01 p.m., sets 10:50 a.m.; Tides: high 11:41 a.m. and low 6:07 a.m. and 6:25 p.m. High and low tides at the following locations may be obtained by subtracting 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 Washington area during the 3 p.m. period was 17 for the pollutant, carbon monoxide. Index values between 0 and 24 indicate good air quality. When the index exceeds 100 the air is considered very unhealthy and individuals with lung, heart and eye ailments are urged to restrict their activity. The forecast for today indicates that the air quality will remain good.

The National Weather Service forecasts the Potomac River stage at Little Falls should fall to near 4.2 feet today. Local Temp., Humidity(TABLE) Time(COLUMN)T.(COLUMN)H. 12 midnight(COLUMN)32(COLUMN)56 1 a.m.(COLUMN)33(COLUMN)56 2 a.m.(COLUMN)32(COLUMN)64 3 a.m.(COLUMN)32(COLUMN)64 4 a.m.(COLUMN)32(COLUMN)64 5 a.m.(COLUMN)31(COLUMN)64 6 a.m.(COLUMN)31(COLUMN)61 7 a.m.(COLUMN)30(COLUMN)69 8 a.m.(COLUMN)32(COLUMN)64 9 a.m.(COLUMN)34(COLUMN)59 10 a.m(COLUMN)37(COLUMN)58 11 a.m.(COLUMN)42(COLUMN)43 12 noon(COLUMN)44(COLUMN)40 1 p.m.(COLUMN)45(COLUMN)38 2 p.m.(COLUMN)43(COLUMN)43 3 p.m.(COLUMN)37(COLUMN)64 4 p.m.(COLUMN)36(COLUMN)72 5 p.m.(COLUMN)35(COLUMN)82 6 p.m.(COLUMN)36(COLUMN)89 7 p.m.(COLUMN)36(COLUMN)89(END TABLE) Temperatures ending 7 a.m. (EST) yesterday:(TABLE) City(COLUMN)H(COLUMN)L Albany(COLUMN)27(COLUMN)18 Abuquerque(COLUMN)45(COLUMN)31 Amarillo(COLUMN)56(COLUMN)28 Anchorage(COLUMN)25(COLUMN)12 Asheville(COLUMN)41(COLUMN)31 Atlanta(COLUMN)47(COLUMN)34 Atlantic City(COLUMN)34(COLUMN)28 Austin(COLUMN)57(COLUMN)50 Baltimore(COLUMN)40(COLUMN)23 Billings(COLUMN)27(COLUMN)17 Birmingham(COLUMN)44(COLUMN)38 Bismarck(COLUMN)27(COLUMN)05 Boise(COLUMN)45(COLUMN)35 Boston(COLUMN)32(COLUMN)22 Brownsville(COLUMN)68(COLUMN)60 Buffalo(COLUMN)27(COLUMN)25 Burlington, Vt.(COLUMN)21(COLUMN)16 Casper(COLUMN)37(COLUMN)18 Charleston, SC(COLUMN)50(COLUMN)40 Charlein, Wd.(COLUMN)40(COLUMN)27 Charlette(COLUMN)46(COLUMN)37 Chovenne(COLUMN)40(COLUMN)22 Chicago(COLUMN)40(COLUMN)23 Cincinnati(COLUMN)39(COLUMN)25 Cleveland(COLUMN)35(COLUMN)26 Columbia, S.C.(COLUMN)51(COLUMN)34 Columbus(COLUMN)38(COLUMN)27 Dal. Ft. Worth(COLUMN)48(COLUMN)42 Davton(COLUMN)40(COLUMN)29 Denver(COLUMN)41(COLUMN)19 Des Moines(COLUMN)36(COLUMN)15 Detroit(COLUMN)28(COLUMN)24 Duluth(COLUMN)15(COLUMN)11 El Paso(COLUMN)63(COLUMN)44 Fairbanks(COLUMN)16(COLUMN)06 Farso(COLUMN)19(COLUMN)03 Flagstaff(COLUMN)43(COLUMN)35 Great Falls(COLUMN)23(COLUMN)10 Hartford(COLUMN)30(COLUMN)15 Helena(COLUMN)26(COLUMN)15 Honolulu(COLUMN)82(COLUMN)68 Houston(COLUMN)51(COLUMN)50 Indianapolis(COLUMN)40(COLUMN)26 Jackson(COLUMN)46(COLUMN)46 Jacksonville(COLUMN)58(COLUMN)46 Juneau(COLUMN)26(COLUMN)14 Kansas City(COLUMN)48(COLUMN)22 Las Vegas(COLUMN)56(COLUMN)50 Little Rock(COLUMN)36(COLUMN)34 Los Angeles(COLUMN)65(COLUMN)56 Louisville(COLUMN)42(COLUMN)32 Memphis(COLUMN)41(COLUMN)38 Miami Beach(COLUMN)71(COLUMN)26 Midland(COLUMN)66(COLUMN)44 Milwaukee(COLUMN)30(COLUMN)26 Mpls.-St. Paul(COLUMN)25(COLUMN)18 Nashville(COLUMN)41(COLUMN)35 New Orleans(COLUMN)62(COLUMN)57 New York(COLUMN)32(COLUMN)28 Norfolk(COLUMN)35(COLUMN)29 North Platte(COLUMN)44(COLUMN)15 Oklahoma City(COLUMN)44(COLUMN)39 Omaha(COLUMN)40(COLUMN)16 Orlando(COLUMN)68(COLUMN)54 Philadelphia(COLUMN)33(COLUMN)23 Phoenix(COLUMN)68(COLUMN)55 Pittsburgh(COLUMN)31(COLUMN)26 Portland, Me(COLUMN)29(COLUMN)10 Portland, Or.(COLUMN)37(COLUMN)33 Providence(COLUMN)29(COLUMN)13 Raleigh(COLUMN)44(COLUMN)32 Rapid City(COLUMN)34(COLUMN)11 Reno(COLUMN)49(COLUMN)40 Richmond(COLUMN)43(COLUMN)27 St. Louis(COLUMN)46(COLUMN)36 St. Prbg-Ta'a(COLUMN)68(COLUMN)55 Salt Lake City(COLUMN)41(COLUMN)40 San Antonio(COLUMN)68(COLUMN)51 San Diego(COLUMN)65(COLUMN)61 San Francisco(COLUMN)59(COLUMN)52 San Juan, Pr.(COLUMN)82(COLUMN)75 St. Ste. Marie(COLUMN)20(COLUMN)13 Seattle(COLUMN)44(COLUMN)39 Shreveport(COLUMN)42(COLUMN)40 Sioux Falls(COLUMN)26(COLUMN)05 Spokane(COLUMN)25(COLUMN)23 Syracuse(COLUMN)29(COLUMN)26 Topeka(COLUMN)52(COLUMN)27 Tucson(COLUMN)61(COLUMN)49 LTulsa(COLUMN)42(COLUMN)39 Washington(COLUMN)42(COLUMN)30 Wichita(COLUMN)51(COLUMN)28(END TABLE) Temperatures Abroad Yesterday(TABLE) City(COLUMN)Weather(COLUMN)Time(COLUMN)Temp Aberdeen(COLUMN)cloudy(COLUMN)1 p.m.(COLUMN)37 Amsterdam(COLUMN)hail(COLUMN)1 p.m.(COLUMN)39 Ankara(COLUMN)cloudy(COLUMN)3 p.m.(COLUMN)39 Athens(COLUMN)pt. cloudy(COLUMN)2 p.m.(COLUMN)64 Auckland(COLUMN)pt. cloudy(COLUMN)midnight(COLUMN)59 Berlin(COLUMN)pt. cloudy(COLUMN)1 p.m.(COLUMN)39 Birmington(COLUMN)cloudy(COLUMN)1 p.m.(COLUMN)41 Brussels(COLUMN)rain(COLUMN)1 p.m.(COLUMN)45 Casablanca(COLUMN)cloudy(COLUMN)noon(COLUMN)57 Genenhageh(COLUMN)pt. cloudy(COLUMN)1 p.m.(COLUMN)37 Dublin(COLUMN)pt. cloudy(COLUMN)1 p.m.(COLUMN)45 Geneva(COLUMN)cloudy(COLUMN)1 p.m.(COLUMN)36 Hong Kong(COLUMN)cloudy(COLUMN)8 p.m.(COLUMN)68 Libson(COLUMN)cloudy(COLUMN)noon(COLUMN)52 Loncon(COLUMN)cloudy(COLUMN)1 p.m.(COLUMN)43 Madrid(COLUMN)clear(COLUMN)1 p.m.(COLUMN)48 Malta(COLUMN)clear(COLUMN)1 p.m.(COLUMN)64 Manila(COLUMN)clear(COLUMN)8 P.m.(COLUMN)79 Moscow(COLUMN)snow(COLUMN)3 p.m.(COLUMN)28 New Delhi(COLUMN)clear(COLUMN)5 p.m.(COLUMN)61 Nice(COLUMN)pt. cldy(COLUMN)1 p.m.(COLUMN)54 Oslo(COLUMN)clear(COLUMN)1 p.m.(COLUMN)18 Paris(COLUMN)pt. cldy(COLUMN)1 p.m.(COLUMN)48 Peking(COLUMN)clear(COLUMN)8 p.m.(COLUMN)28 Rome(COLUMN)pt. cldy(COLUMN)1 p.m.(COLUMN)57 Saigon(COLUMN)pt. cldy(COLUMN)8 p.m.(COLUMN)84 Sofia(COLUMN)rain(COLUMN)2 p.m.(COLUMN)41 Stockholm(COLUMN)cloudy(COLUMN)1 p.m.(COLUMN)28 Sydney(COLUMN)clear(COLUMN)10 p.m.(COLUMN)72 Tel Aviv(COLUMN)cloudy(COLUMN)2 p.m.(COLUMN)61 Tokyo(COLUMN)cloudy(COLUMN)9 p.m.(COLUMN)55 Tunis(COLUMN)pt. cldy(COLUMN)1 p.m.(COLUMN)64 Venna(COLUMN)cloudy(COLUMN)1 p.m.(COLUMN)41 Warsaw(COLUMN)rain(COLUMN)1 p.m.(COLUMN)36(END TABLE) Temperatures (Western Hemisphere)(TABLE) City(COLUMN)Weather(COLUMN)H(COLUMN)T Acapulco(COLUMN)fair(COLUMN)86(COLUMN)72 Barbados(COLUMN)fair(COLUMN)84(COLUMN)72 Bermuda(COLUMN)cloudy(COLUMN)69(COLUMN)64 Bogota(COLUMN)clear(COLUMN)66(COLUMN)45 Calsery(COLUMN)snow(COLUMN)19(COLUMN)03 Edmonton(COLUMN)snow(COLUMN)23(COLUMN)07 Havana(COLUMN)fair(COLUMN)73(COLUMN)61 Kingston(COLUMN)rain(COLUMN)86(COLUMN)73 Montego Bay(COLUMN)cloudy(COLUMN)81(COLUMN)73 Mexico City(COLUMN)fair(COLUMN)75(COLUMN)49 Monterrey(COLUMN)fair(COLUMN)75(COLUMN)52 Montreal(COLUMN)cloudy(COLUMN)19(COLUMN)09 Nassau(COLUMN)fair(COLUMN)73(COLUMN)67 Ottawa(COLUMN)cloudy(COLUMN)16(COLUMN)05 Regina(COLUMN)clear(COLUMN)19(COLUMN)-24 St. Kitts(COLUMN)fair(COLUMN)85(COLUMN)72 St. Thomas(COLUMN)fair(COLUMN)84(COLUMN)75 Toronto(COLUMN)fair(COLUMN)21(COLUMN)19 Vancouver(COLUMN)fog(COLUMN)39(COLUMN)34 Veracruz(COLUMN)pt. cldy(COLUMN)82(COLUMN)64 Winnipeg(COLUMN)clear(COLUMN)00(COLUMN)-15(END TABLE)