Washington: Today - Fair and warm, high in the low 90s, low near 70. The chance of rain is 10 per cent through tonight. Thursday - Partly cloudy, war and humid, high in the low 90s.

Maryland and Virginia: Today - Fair and continued warm, high in the low 90s, low in the upper 60s. Thursday - Partly cloudy, warm and humid, high near 90.

Lower Potomac and Chesapeake Bay: Today - Fair with fair visibility through tonight. Winds will become easterly near 10 knots by afternoon.

Extended Area Forecast for Friday through Sunday - Continued fair, warm and humid. Highs will average from the mid 80s to low 90s and the lows will be near 70. Normal Washington temperatures for the period are a high of 84 and a low of 65.

Atlantic Ocean Beaches from Cape May to Cape Hatteras: Today and Thursday - Partly cloudy, warm and humid, highs in the 80s. Water temperatures should range from the lower 70s in the north to near 80 in the south.

West Virginia: Today - Sunny, warm and humid, highs ranging from the mid 80s to low 90s and lows from the 60s to low 70s. Thursday - Continued warm and humid, high near 90.

The national weather forecast for today - Thundershowers will extend along the Gulf of Mexico, through the Louisiana Delta and into central Texas. Showers and thundershows will also be scattered from the lower Ohio Valley through the upper Great Lakes, the northern half of the Mississippi Valley, the northern Plains, eastern portions of the central Plains, the upper half of the Rockies and the upper Missouri Valley. Rain showers will also extend over the Pacific Northwest. Cool temperatures will extend from the west half of the central and northern Plains, across the northern half of the Rockies and eastern portions of the northern Intermountain region. Temperatures will be mid over the Pacific Coast, across the Southeast, to the northern Mississippi Valley. Elsewhere, temperatures will remain seasonably warm.

ALMANAC DATA FOR Aug. 31, 1977: Sun rises 6:36 a.m., sets 7:40 p.m.; moon rises 9:12 p.m., sets 9:26 a.m. Tides: High 10:40 a.m. and 11:00 p.m.; low 5:04 a.m. and 5:23 p.m. High and low tides at the following locations can be obtained by subtracting the hours indicated from the tides above. Annapolis (3 1/2); Bloody Point Lighthouse (4 1/2); Deale, Md. (4 1/2); Colonial Beach (6). Norfolk (1 1/2); Virginia Beach (6); Solomon Island (6 1/2); Point Lookout (7). Pollen count: 20 ragweed (note: 7 or higher is considered undesirable).

The Council of Governments' Air Quality Index for yesterday showed the high reading in the Washington areas during the 4 p.m. period was 120 for the pollutant, photochemcial oxidants. Index values between 100 and 249 indicate unhealthy 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 a pollution alert in effect as of 4 p.m. Tuesday.

The National Weather Service forecasts the Potomac River stage at Little Falls should remain near 2.7 feet today.

Washington data at 8 p.m. (EDT) yesterday: Highest temperature since 8 a.m. yesterday, 92 degrees at 2:30 p.m. Lowest temperature since midnight, 73 degrees at 5:35 a.m. Excess of temperature since August 1, 53 degrees. Excess of temperature since Jan. 1, 330 degrees. Record high temperature for today, 100 degrees in 1953. Record low temperature for today, 49 degrees in 1934. Relative humidity: Maximum, 97 per cent at 6 a.m.; Minimum, 56 per cent at 3 p.m. 24 hour precipitation, 40 inches. Excess of precipitation since Aug. 1, 20 inches. Deficiency/Excess of precipitation since Jan. 1, 6.28 inches. Highest observed wind since 8 a.m. 15 miles per hour from the southeast at 6 p.m. Peak gust since 8 a.m., 51 miles per hour from the southeast at 5:38 p.m. Local Temp., Humidity(TABLE) Time(COLUMN)T.(COLUMN)H. 12 mid.(COLUMN)78(COLUMN)88 1 a.m.(COLUMN)77(COLUMN)91 2 a.m.(COLUMN)76(COLUMN)91 3 a.m.(COLUMN)76(COLUMN)91 4 a.m.(COLUMN)75(COLUMN)94 5 a.m.(COLUMN)75(COLUMN)94 6 a.m.(COLUMN)74(COLUMN)97 7 a.m.(COLUMN)74(COLUMN)97 8 a.m.(COLUMN)76(COLUMN)91 9 a.m.(COLUMN)78(COLUMN)88 10 a.m.(COLUMN)81(COLUMN)80 11 a.m.(COLUMN)84(COLUMN)72 12 noon(COLUMN)86(COLUMN)68 1 p.m.(COLUMN)89(COLUMN)62 2 p.m.(COLUMN)91(COLUMN)58 3 p.m.(COLUMN)91(COLUMN)58 4 p.m.(COLUMN)91(COLUMN)56 5 p.m.(COLUMN)90(COLUMN)56 6 p.m.(COLUMN)76(COLUMN)86 7 p.m.(COLUMN)77(COLUMN)82(END TABLE) Temperatures ending 8 a.m. (EDT) yesterday.(TABLE) City(COLUMN)H.(COLUMN)L. Albany(COLUMN)92(COLUMN)67 Albuquerque(COLUMN)90(COLUMN)67 Amarillo(COLUMN)78(COLUMN)68 Anchorage(COLUMN)69(COLUMN)98 Asheville(COLUMN)84(COLUMN)62 Atlanta(COLUMN)86(COLUMN)70 Atlantic City(COLUMN)79(COLUMN)71 Austin(COLUMN)94(COLUMN)76 Baltimore(COLUMN)92(COLUMN)71 Billings(COLUMN)81(COLUMN)52 Birmingham(COLUMN)91(COLUMN)76 Bismarck(COLUMN)84(COLUMN)58 Boise(COLUMN)75(COLUMN)57 Boston(COLUMN)95(COLUMN)74 Brownsville(COLUMN)93(COLUMN)73 Buffalo(COLUMN)83(COLUMN)62 Burlington, VT.(COLUMN)92(COLUMN)64 Casper(COLUMN)81(COLUMN)45 Charleston, S.C.(COLUMN)88(COLUMN)75 Charleston, W.V.(COLUMN)88(COLUMN)70 Charlotte(COLUMN)91(COLUMN)70 Cheyenne(COLUMN)76(COLUMN)48 Chicago(COLUMN)76(COLUMN)58 Cincinnati(COLUMN)82(COLUMN)71 Cleveland(COLUMN)79(COLUMN)64 Columbia, S.C.(COLUMN)90(COLUMN)69 Columbus(COLUMN)84(COLUMN)70 Dal.-Ft. Worth(COLUMN)91(COLUMN)71 Dayton(COLUMN)78(COLUMN)69 Denver(COLUMN)84(COLUMN)58 Des Monies(COLUMN)78(COLUMN)64 Detroit(COLUMN)79(COLUMN)64 Duluth(COLUMN)72(COLUMN)58 El Paso(COLUMN)93(COLUMN)68 Fairbanks(COLUMN)53(COLUMN)45 Fargo(COLUMN)79(COLUMN)62 Flagstaff(COLUMN)83(COLUMN)47 Great Falls(COLUMN)70(COLUMN)50 Hartford(COLUMN)95(COLUMN)70 Helena(COLUMN)70(COLUMN)45 Honolulu(COLUMN)89(COLUMN)75 Houston(COLUMN)88(COLUMN)74 Indianapolis(COLUMN)76(COLUMN)69 Jackson(COLUMN)90(COLUMN)72 Jacksonville(COLUMN)90(COLUMN)72 Juneau(COLUMN)57(COLUMN)41 Kansas City(COLUMN)78(COLUMN)65 Las Vegas(COLUMN)105(COLUMN)76 Little Rock(COLUMN)87(COLUMN)71 Los Angeles(COLUMN)82(COLUMN)69 Louisville(COLUMN)87(COLUMN)73 Memphis(COLUMN)90(COLUMN)72 Miami Beach(COLUMN)84(COLUMN)71 Midland(COLUMN)92(COLUMN)70 Milwaukee(COLUMN)68(COLUMN)52 Mpls.-St. Paul(COLUMN)76(COLUMN)62 Naashville(COLUMN)92(COLUMN)70 New Orleans(COLUMN)86(COLUMN)75 New York(COLUMN)87(COLUMN)73 Norfolk(COLUMN)88(COLUMN)72 North Platte(COLUMN)75(COLUMN)66 Oklahoma City(COLUMN)86(COLUMN)20 Omaha(COLUMN)79(COLUMN)59 Orlando(COLUMN)83(COLUMN)73 Philadelphia(COLUMN)90(COLUMN)72 Phoenix(COLUMN)107(COLUMN)81 Pittsburgh(COLUMN)86(COLUMN)66 Portland, Me.(COLUMN)93(COLUMN)69 Portland, Or.(COLUMN)67(COLUMN)55 Providence(COLUMN)90(COLUMN)71 Raleigh(COLUMN)88(COLUMN)68 Rapid City(COLUMN)84(COLUMN)52 Reno(COLUMN)89(COLUMN)46 Richmond(COLUMN)90(COLUMN)68 St. Louis(COLUMN)79(COLUMN)64 St. Prbg.-Tampa(COLUMN)89(COLUMN)76 Salt Lake City(COLUMN)84(COLUMN)60 San Antonio(COLUMN)94(COLUMN)75 San Diego(COLUMN)77(COLUMN)69 San Francisco(COLUMN)83(COLUMN)62 San Juan(COLUMN)87(COLUMN)75 St. Ste. Marie(COLUMN)65(COLUMN)45 Seattle(COLUMN)63(COLUMN)53 Shreveport(COLUMN)90(COLUMN)70 Sioux Falls(COLUMN)79(COLUMN)60 Spokane(COLUMN)68(COLUMN)50 Syracuse(COLUMN)90(COLUMN)66 Topeka(COLUMN)85(COLUMN)65 Tucson(COLUMN)102(COLUMN)75 Tulsa(COLUMN)82(COLUMN)72 Washington(COLUMN)91(COLUMN)73 Wichita(COLUMN)80(COLUMN)69(END TABLE) Temperatures Abroad Yesterday(TABLE) City(COLUMN)Weather(COLUMN)Time(COLUMN)Temp. Aberdeen(COLUMN)rain(COLUMN)1 p.m.(COLUMN)54 Amsterdam(COLUMN)clear(COLUMN)1 p.m.(COLUMN)70 Ankara(COLUMN)clear(COLUMN)3 p.m.(COLUMN)79 Athens(COLUMN)clear(COLUMN)2 p.m.(COLUMN)95 Auckland(COLUMN)cloudy(COLUMN)midnight(COLUMN)50 Berlin(COLUMN)clear(COLUMN)2 p.m.(COLUMN)86 Birmingham(COLUMN)cloudy(COLUMN)1 p.m.(COLUMN)61 Brussels(COLUMN)cloudy(COLUMN)1 p.m.(COLUMN)63 Cairo(COLUMN)clear(COLUMN)2 p.m.(COLUMN)90 Casablanca(COLUMN)clear(COLUMN)noon(COLUMN)77 Copenhagen(COLUMN)clear(COLUMN)1 p.m.(COLUMN)70 Dublin(COLUMN)cloudy(COLUMN)1 p.m.(COLUMN)52 Geneva(COLUMN)pt. cldy(COLUMN)1 p.m.(COLUMN)70 Hong Kong(COLUMN)cloudy(COLUMN)6 p.m.(COLUMN)82 Lisbon(COLUMN)clear(COLUMN)noon(COLUMN)79 London(COLUMN)pt. cldy(COLUMN)1 p.m.(COLUMN)64 Madrid(COLUMN)clear(COLUMN)1 p.m.(COLUMN)73 Malta(COLUMN)clear(COLUMN)1 p.m.(COLUMN)84 Manila(COLUMN)cloudy(COLUMN)8 p.m.(COLUMN)81 Moscow(COLUMN)pt. cldy(COLUMN)3 p.m.(COLUMN)68 New Delhi(COLUMN)pt. cldy(COLUMN)5 p.m.(COLUMN)86 Nice(COLUMN)rain(COLUMN)1 p.m.(COLUMN)63 Oslo(COLUMN)pt. cldy(COLUMN)1 p.m.(COLUMN)66 Paris(COLUMN)clear(COLUMN)1 p.m.(COLUMN)68 Peking(COLUMN)rain(COLUMN)8 p.m.(COLUMN)72 Rome(COLUMN)rain(COLUMN)1 p.m.(COLUMN)77 Saigon(COLUMN)rain(COLUMN)8 p.m.(COLUMN)79 Stockholm(COLUMN)cloudy(COLUMN)1 p.m.(COLUMN)64 Sydney(COLUMN)rain(COLUMN)10 p.m.(COLUMN)59 Tel Aviv(COLUMN)clear(COLUMN)2 p.m.(COLUMN)91 Tokyo(COLUMN)cloudy(COLUMN)9 p.m.(COLUMN)77 Tunis(COLUMN)pt. cldy(COLUMN)1 p.m.(COLUMN)79 Vienna(COLUMN)clear(COLUMN)1 p.m.(COLUMN)77 Warsaw(COLUMN)clear(COLUMN)10 p.m.(COLUMN)75(END TABLE) Temperatures (Western Hemisphere)(TABLE) City(COLUMN)Weather(COLUMN)High(COLUMN)Low Acapulco(COLUMN)pt. cldy(COLUMN)91(COLUMN)77 Barbados(COLUMN)pt. cldy(COLUMN)87(COLUMN)81 Bermuda(COLUMN)pt. cldy(COLUMN)87(COLUMN)78 Calgary(COLUMN)cloudy(COLUMN)57(COLUMN)43 Culiacan(COLUMN)cloudy(COLUMN)91(COLUMN)75 Edmonton(COLUMN)rain(COLUMN)55(COLUMN)48 Kingston(COLUMN)clear(COLUMN)90(COLUMN)78 Montego Bay(COLUMN)clear(COLUMN)91(COLUMN)77 Mexico City(COLUMN)haze(COLUMN)72(COLUMN)57 Monterrey(COLUMN)cloudy(COLUMN)81(COLUMN)51 Montreal(COLUMN)cloudy(COLUMN)88(COLUMN)59 Nassau(COLUMN)cloudy(COLUMN)87(COLUMN)75 Ottawa(COLUMN)cloudy(COLUMN)88(COLUMN)59 Regina(COLUMN)pt. cldy(COLUMN)73(COLUMN)46 St. Kitts(COLUMN)pt. cldy(COLUMN)89(COLUMN)75 Toronto(COLUMN)clear(COLUMN)79(COLUMN)50 Vancouver(COLUMN)clear(COLUMN)68(COLUMN)46 Winnipeg(COLUMN)cloudy(COLUMN)73(COLUMN)55(END TABLE)