Washington: Today - Partly cloudy, highs in mid to upper 70s lows in mid to upper 50s. Chance of rain is 10 per cent through tonight. Saturday - partly cloudy, highs in 70s.

Maryland and Virginia: Today - Partly cloudy, highs in 70s and lows in 50s. Chance of rain in western Maryland today. Saturday - Partly cloudy, high in 70s.

West Virginia: Today - Partly cloudy, highs in upper in 60s to mid 70s, lows in mid to upper 50s. Saturday - Partly cloudy, highs in mid to upper 70s.

Lower Potomac and Chesapeake Bay: Today - Partly cloudy skies with fair visibility through tonight. Winds should be variable at 7 to 12 knots today and easterly at about 10 knots tonight.

Extended Area Outlook: For Sunday through Tuesday - Chance of rain Sunday followed by fair skies through remainder of period. Temperatures should range from Sunday's high near 80 and lows in mid 50s to mid 60s to Tuesday's highs near 70 and lows near 50.

The National Weather Forecast for Today - Showers and thunderstorms will be scattered over the central and northern Plains, the middle and upper Mississippi Valley and the Great Lakes region. Thunderstorms will also be found over Florida. Rain is likely to spread into Washington and western Oregon. It will be cool in the northwest quarter of the country and in New England. Warm temperatures will prevail over the southwest. It will not be quite as hot in Texas. Mild readings will be the rule elsewhere in the nation.

The Council of Governments' Air Quality Index for yesterday showed the high reading in the Washington area during the 2 to 3 p.m. period was 25 for the pollutant, photochemical oxidants. Index values between 25 and 29 indicate fair air quality. When the index exceeds 100 the air 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 about the same.

The National Weather Service forecasts the Potomac River stage at Little Falls should remain near 2.6 feet through today.

Almanac Data for Sept. 23, 1977. Sun rises 6:56 a.m., sets 7:04 p.m. Moon rises 4:50 p.m. and sets 2:59 a.m. Tides: High 5:20 a.m. and 5:59 p.m. low and 12:11 p.m. and 12:34 a.m. High and low tides at the following locations can 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). Pollen Count 42 ragweed (note: More than 7 is considered undesirable.)

Washington data at 8 p.m. (EDT) yesterday: Highest temperature since 8 p.m. yesterday, 75 degrees at 1:45 p.m. Lowest temperature since midnight 62 degrees at 4:40 a.m. Excess of temperature since Sept. 1, 71 degrees. Excess of temperature since Jan. 1, 407 degrees. Record high temperature for today 98 degrees in 1895. Record low temperature for today 36 degrees in 1904. Relative humidity: Maximum, 93 per cent at 5 a.m.; Minimum, 56 per cent at 2 p.m. 24 hour precipitation, none. Deficiency of precipitation since Sept. 1, 2:11 inches. Deficiency of precipitation since Jan. 1, 8:52 inches. Highest observed wind since 8 a.m. 12 miles per hour from the E.N.E. at 2:53 p.m. Peak gust since 8 a.m., 16 miles per hour from the north at 2:10 p.m. Local Temp., Humidity(TABLE) Time(COLUMN)T.(COLUMN) . 12 midn.(COLUMN)68(COLUMN)76 1 a.m.(COLUMN)67(COLUMN)78 2 a.m.(COLUMN)65(COLUMN)84 3 a.m.(COLUMN)65(COLUMN)84 4 a.m.(COLUMN)64(COLUMN)87 5 a.m.(COLUMN)62(COLUMN)93 6 a.m.(COLUMN)62(COLUMN)93 7 a.m.(COLUMN)62(COLUMN)93 8 a.m.(COLUMN)63(COLUMN)93 9 a.m.(COLUMN)65(COLUMN)87 10 a.m.(COLUMN)67(COLUMN)87 11 a.m.(COLUMN)69(COLUMN)81 12 noon(COLUMN)71(COLUMN)73 1 p.m.(COLUMN)72(COLUMN)64 2 p.m.(COLUMN)75(COLUMN)56 3 p.m.(COLUMN)73(COLUMN)76 4 p.m.(COLUMN)74(COLUMN)69 5 p.m.(COLUMN)74(COLUMN)66 6 p.m.(COLUMN)73(COLUMN)74(END TABLE) Temperatures ending 8 a.m. (EDT) yesterday.(TABLE) City(COLUMN)(COLUMN). Albany(COLUMN)54(COLUMN)50 Albuquerque(COLUMN)81(COLUMN)51 Amarillo(COLUMN)92(COLUMN)55 Anchorage(COLUMN)52(COLUMN)45 Asheville(COLUMN)80(COLUMN)57 Atlanta(COLUMN)81(COLUMN)56 Atlantic City(COLUMN)66(COLUMN)58 Austin(COLUMN)91(COLUMN)69 Baltimore(COLUMN)75(COLUMN)59 Birmingham 82(COLUMN)58 Bismarck(COLUMN)58(COLUMN)54 Boise(COLUMN)62(COLUMN)34 Boston(COLUMN)55(COLUMN)47 Brownsville(COLUMN)94(COLUMN)73 Buffalo(COLUMN)55(COLUMN)51 Burlington Vt.(COLUMN)55(COLUMN)50 Casper(COLUMN)65(COLUMN)32 Charleston S.C.(COLUMN)90(COLUMN)69 Charleston WVa(COLUMN)69(COLUMN)54 Cheyenne(COLUMN)65(COLUMN)40 Chicago(COLUMN)63(COLUMN)57 Cincinnati(COLUMN)69(COLUMN)50 Cleveland(COLUMN)59(COLUMN)50 Columbia SC(COLUMN)89(COLUMN)64 Columbus, Ohio(COLUMN)59(COLUMN)51 Dal. Ft. Worth(COLUMN)94(COLUMN)68 Dayton(COLUMN)59(COLUMN)47 Denver(COLUMN)78(COLUMN)41 Des Moines(COLUMN)75(COLUMN)53 Detroit(COLUMN)66(COLUMN)53 Duluth(COLUMN)51(COLUMN)48 El Paso(COLUMN)91(COLUMN)58 Fairbanks(COLUMN)52(COLUMN)39 Fargo(COLUMN)65(COLUMN)53 Great Falls(COLUMN)63(COLUMN)42 Hartford(COLUMN)56(COLUMN)46 Helena(COLUMN)62(COLUMN)40 Indianapolis(COLUMN)65(COLUMN)52 Jackson, Miss.(COLUMN)86(COLUMN)62 Juneau(COLUMN)5H3(COLUMN)50 Kansas City(COLUMN)78(COLUMN)61 Las Vegas(COLUMN)76(COLUMN)57 Little Rock(COLUMN)81(COLUMN)63 Los Angeles(COLUMN)82(COLUMN)60 Louisville(COLUMN)76(COLUMN)56 Memphis(COLUMN)84(COLUMN)63 Miami Beach(COLUMN)87(COLUMN)83 Midland(COLUMN)100(COLUMN)69 Milwaukee(COLUMN)58(COLUMN)45 Mpls.-St. Paul(COLUMN)67(COLUMN)54 Nashville(COLUMN)78(COLUMN)4 New Orleans(COLUMN)87(COLUMN)71 New York(COLUMN)60(COLUMN)52 Norfolk(COLUMN)78(COLUMN)66 North Platte(COLUMN)80(COLUMN)40 Oklahoma City(COLUMN)96(COLUMN)69 Omaha(COLUMN)77(COLUMN)52 Philadelphia(COLUMN)68(COLUMN)57 Phoenix(COLUMN)96(COLUMN)71 Pittsburgh(COLUMN)62(COLUMN)55 Portland, Me.(COLUMN)45(COLUMN)37 Portland, Ore.(COLUMN)67(COLUMN)43 Providence(COLUMN)54(COLUMN)46 Raleigh(COLUMN)80(COLUMN)54 Rapid City(COLUMN)66(COLUMN)38 Reno(COLUMN)75(COLUMN)86 Richmond(COLUMN)81(COLUMN)58 St. Louis(COLUMN)68(COLUMN)57 Salt Lake City(COLUMN)46(COLUMN)50 San Antonio(COLUMN)70(COLUMN)71 San Diego(COLUMN)75(COLUMN)66 San Francisco(COLUMN)74(COLUMN)56 St. Ste. Marie(COLUMN)54(COLUMN)50 Seattle(COLUMN)63(COLUMN)46 Shreveport(COLUMN)88(COLUMN)60 Spokane(COLUMN)55(COLUMN)33 Syracuse(COLUMN)58(COLUMN)55 Topeka(COLUMN)83(COLUMN)55 Tucson(COLUMN)94(COLUMN)68 Washington(COLUMN)77(COLUMN)62 Wichita(COLUMN)93(COLUMN)62(END TABLE) Temperatures Abroad Yesterday(TABLE) City(COLUMN)Weather(COLUMN)Time(COLUMN)Temp. Aberdeen(COLUMN)cloudy(COLUMN)1 p.m.(COLUMN)52 Amsterdam(COLUMN)cloudy(COLUMN)2 p.m.(COLUMN)59 Ankara(COLUMN)clear(COLUMN)3 p.m.(COLUMN)86 Athens(COLUMN)clear(COLUMN)3 p.m.(COLUMN)85 Auckland(COLUMN)clear(COLUMN)midnight(COLUMN)52 Berlin(COLUMN)cloudy(COLUMN)1 p.m.(COLUMN)54 Birmingham(COLUMN)cloudy(COLUMN)1 p.m.(COLUMN)52 Brussels(COLUMN)cloudy(COLUMN)1 p.m.(COLUMN)55 Cairo(COLUMN)clear(COLUMN)2 p.m.(COLUMN)93 Casablanca(COLUMN)pt. cldy(COLUMN) noon(COLUMN)72 Copenhagen(COLUMN)1 p.m.(COLUMN)63 Dublin(COLUMN)cloudy(COLUMN)1 p.m.(COLUMN)54 Geneva(COLUMN)clear(COLUMN)1 p.m.(COLUMN)55 Hong Kong(COLUMN)cloudy(COLUMN)8 p.m.(COLUMN)75 Lisbon(COLUMN)cloudy(COLUMN)noon(COLUMN)72 London(COLUMN)cloudy(COLUMN)1 p.m.(COLUMN)57 Madrid(COLUMN)pt. cldy(COLUMN)1 p.m.(COLUMN)64 Malta(COLUMN)clear(COLUMN)1 p.m.(COLUMN)81 Manila(COLUMN)pt. cldy(COLUMN)8 p.m.(COLUMN)82 Moscow(COLUMN)rain(COLUMN)3 p.m.(COLUMN)48 New Delhi(COLUMN)clear(COLUMN)5 p.m.(COLUMN)91 Nice(COLUMN)cloudy(COLUMN)1 p.m.(COLUMN)59 Oslo(COLUMN)clear(COLUMN)1 p.m.(COLUMN)61 Paris(COLUMN)cloudy(COLUMN)1 p.m.(COLUMN)55 Peking(COLUMN)clear(COLUMN)8 p.m.(COLUMN)63 Rome(COLUMN)rain(COLUMN)8 p.m.(COLUMN)59 Saigon pt. cldy(COLUMN)8 p.m.(COLUMN)81 Sofia(COLUMN)pt. cldy(COLUMN)2 p.m.(COLUMN)72 Stockholm(COLUMN)cloudy(COLUMN)1 p.m.(COLUMN)55 Sydney(COLUMN)clear(COLUMN)10 p.m.(COLUMN)64 Tel Aviv(COLUMN)clear(COLUMN)2 p.m.(COLUMN)86 Tokyo(COLUMN)cloudy(COLUMN)9 p.m.(COLUMN)63 Tunis(COLUMN)pt. cldy(COLUMN)1 p.m.(COLUMN)84 Vienna(COLUMN)pt. cldy(COLUMN)1 p.m.(COLUMN)57 Warsaw(COLUMN)rain(COLUMN)1 p.m.(COLUMN)50(END TABLE) Temperatures (Western Henmisphere)(TABLE) City(COLUMN)Weather(COLUMN)High(COLUMN)Low Acapulco(COLUMN)pt. cldy(COLUMN)87(COLUMN)79 Barbados(COLUMN)pt. cldy(COLUMN)87(COLUMN)84 Bermuda(COLUMN)cloudy(COLUMN)86(COLUMN)75 Bogota(COLUMN)cloudy(COLUMN)66(COLUMN)41 Calgary(COLUMN)cloudy(COLUMN)52(COLUMN)37 Culiacan(COLUMN)pt. cldy(COLUMN)93(COLUMN)78 Edmonton(COLUMN)cloudy(COLUMN)59(COLUMN)45 Havana(COLUMN)cloudy(COLUMN)91(COLUMN)77 Kingston(COLUMN)pt. cldy(COLUMN)90(COLUMN)79 Montego Bay(COLUMN)pt. cldy(COLUMN)90(COLUMN)74 Mexico City(COLUMN)pt. cldy(COLUMN)74(COLUMN)53 Monterrey(COLUMN)pt. cldy(COLUMN)92(COLUMN)74 Montreal(COLUMN)cloudy(COLUMN)50(COLUMN)41 Nassau(COLUMN)pt. cldy(COLUMN)89(COLUMN)74 Ottawa(COLUMN)cloudy(COLUMN)48(COLUMN)45 Regina(COLUMN)clear(COLUMN)68(COLUMN)45 St. Kitts(COLUMN)cloudy(COLUMN)84(COLUMN)63 Toronto cloudy(COLUMN)54(COLUMN)48 Vancouver(COLUMN)clear(COLUMN)59(COLUMN)41 Veracruz(COLUMN)pt. cldy(COLUMN)86(COLUMN)73 Winnipeg(COLUMN)rain(COLUMN)66(COLUMN)52 (END TABLE)