Washington: Today - Partly cloudy, high in low 80s, low in low to mid 60s. Chance of rain is 10 per cent today, 20 per cent tonight. Monday - Partly cloudy with chance of rain, high in low 80s.

Maryland and Virginia: Today - Partly cloudy highs in mid 70s to mid 80s, lows in 60s. Chance of rain tonight. Monday - Partly cloudy with chance of rain, highs in mid 70s to mid 80s.

Lower Potomac and Chesapeake Bay: Today - Partly cloudy with generally good visibility through tonight. Winds should be variable at less than 8 knots this morning, becoming southerly at about 12 knots this afternoon and evening.

Extended Area Outlook: For Tuesday through Thursday - partly cloudly with highs in 80s and lows in 60s through period. It should be slightly cooler in mountains. There is a chance of rain Wednesday, and Thursday. Washington's normal temperature range for this time of year is from 86 to 67.

West Virginia: Today - Partly cloudy with chance of rain, highs in 70s to near 80s, lows in 50s to low 60s. Monday - Partly cloudy with chance of rain, highs in 70s to near 80.

Atantic Ocean Beaches from Cape May through Maryland: Today - Partly cloudy, high near 80 Monday - partly cloudy with chance of rain, high near 80. Water temperatures should be in low to mid 80s both days.

Atlantic OCean Beaches from Cape Hateras through Virginia: Today - partly cloudy, high in low 80s. Monday - partly cloudy with chance of rain, high in low 80s. Water temperatures should be near 80 both days.

The National Weather Forecast for Today - Showers and thundershowers are likely from central Florida and southern Georgia along the Gulf Coast to central Louisiana and in eastern Michigan. Scattered showers and thundershowers are anticipated from the Virginia and Carolina coastal regions through the central Gulf Coast states to north and east Texas. Eastern Wyoming and the Great Lakes region also expect scattered showers and thundershowers. Somewhat cooler air will be pentrating the northern Plains and upper Mississippi Valley from Canada with little change in temperatures predicted elsewhere. The northern intermountain area will continue quite hot with slightly cooler for northeast Washington. The south will be seasonably warm while the midwest and east will continue mild.

The National Weather Service forecasts the Potomac River stage at Little Falls and be near 2.9 feet today.

ALMANAC DATA FOR Sunday, Aug. 21, 1977: Sun rises 6:27 a.m. sets 7:55 p.m.; moon rises 1:33 a.m., sets 12:07 a.m. Tides: High 1:10 a.m. and 1:31 p.m., low 8:10 a.m. and 8:16 p.m. High and low tides at the following location can be obtained by subtraction 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 (1); Solomons Island (6 1/2); Point Lookout (7). Local Temp., Humidity(TABLE) Time(COLUMN)T.(COLUMN)H. 12 mid.(COLUMN)70(COLUMN)66 1 a.m.(COLUMN)78(COLUMN)66 2 a.m.(COLUMN)69(COLUMN)73 3 a.m.(COLUMN)69(COLUMN)71 4 a.m.(COLUMN)70(COLUMN)68 5 a.m.(COLUMN)69(COLUMN)76 6 a.m.(COLUMN)69(COLUMN)76 7 a.m.(COLUMN)69(COLUMN)76 8 a.m.(COLUMN)69(COLUMN)76 9 a.m.(COLUMN)70(COLUMN)76 10 a.m.(COLUMN)72(COLUMN)54 11 a.m.(COLUMN)75(COLUMN)50 12 noon(COLUMN)76(COLUMN)46 1 p.m.(COLUMN)77(COLUMN)46 2 p.m.(COLUMN)79(COLUMN)47 3 p.m.(COLUMN)79(COLUMN)45 4 p.m.(COLUMN)73(COLUMN)45 5 p.m.(COLUMN)79(COLUMN)45(END TABLE) Temperatures ending 8 a.m. (EDT) Yesterday(TABLE) City(COLUMN)H.(COLUMN)L. Albany(COLUMN)70(COLUMN)50 Albuquerque(COLUMN)91(COLUMN)66 Amarillo(COLUMN)84(COLUMN)60 Anchorage(COLUMN)66(COLUMN)54 Asheville(COLUMN)77(COLUMN)58 Atlanta(COLUMN)81(COLUMN)63 Atlantic City(COLUMN)77(COLUMN)65 Austin(COLUMN)69(COLUMN)78 Baltimore(COLUMN)90(COLUMN)61 Billings(COLUMN)68(COLUMN)62 Birmingham(COLUMN)89(COLUMN)74 Bismarck(COLUMN)84(COLUMN)45 Boise(COLUMN)87(COLUMN)70 Boston(COLUMN)71(COLUMN)58 Brownsville(COLUMN)83(COLUMN)77 Buffalo(COLUMN)68(COLUMN)47 Burlington, Vt.(COLUMN)71(COLUMN)50 Capser(COLUMN)87(COLUMN)52 Charlt'n, S.C.(COLUMN)79(COLUMN)71 Charlton, W.Va.(COLUMN)76(COLUMN)52 Charlotte, N.C.(COLUMN)82(COLUMN)63 Cheyenne(COLUMN)76(COLUMN)53 Chicago(COLUMN)70(COLUMN)60 Cincinnati(COLUMN)76(COLUMN)55 Cleveland(COLUMN)70(COLUMN)52 Columbia, S.C.(COLUMN)81(COLUMN)65 Columbus, Ohio(COLUMN)73(COLUMN)50 Dal.Ft. Worth(COLUMN)89(COLUMN)70 Dayton(COLUMN)75(COLUMN)69 Denver(COLUMN)74(COLUMN)54 Des Moines(COLUMN)84(COLUMN)59 Detroit(COLUMN)76(COLUMN)48 Duluth(COLUMN)65(COLUMN)49 El Paso(COLUMN)98(COLUMN)70 Fairbanks(COLUMN)77(COLUMN)55 Fargo(COLUMN)79(COLUMN)53 Flagstaff(COLUMN)83(COLUMN)55 Great Falls(COLUMN)86(COLUMN)53 Hartford(COLUMN)78(COLUMN)50 Helena(COLUMN)53(COLUMN)55 Honolulu(COLUMN)89(COLUMN)77 Houston(COLUMN)87(COLUMN)79 Indianapolis(COLUMN)77(COLUMN)62 Jackson, Miss.(COLUMN)87(COLUMN)70 Jacksonville(COLUMN)89(COLUMN)77 Juneau(COLUMN)80(COLUMN)50 Kansas City(COLUMN)79(COLUMN)65 Las Vegas(COLUMN)100(COLUMN)79 Little Rock(COLUMN)80(COLUMN)65 Los Angeles(COLUMN)86(COLUMN)70 Louisville(COLUMN)80(COLUMN)58 Memphis(COLUMN)82(COLUMN)70 Miami Beach(COLUMN)90(COLUMN)79 Midland(COLUMN)103(COLUMN)79 Milwaukee(COLUMN)63(COLUMN)52 Mpls-St. Paul(COLUMN)74(COLUMN)52 Nashville(COLUMN)70(COLUMN)64 New Orleans(COLUMN)90(COLUMN)77 New York(COLUMN)76(COLUMN)64 Norfolk(COLUMN)79(COLUMN)64 Nort Platte(COLUMN)86(COLUMN)53 Oklahoma City(COLUMN)73(COLUMN)63 Omaha(COLUMN)53(COLUMN)57 Orlando(COLUMN)94(COLUMN)75 Philadelphia(COLUMN)78(COLUMN)61 Phoenix(COLUMN)107(COLUMN)87 Pittsburgh(COLUMN)68(COLUMN)46 Portland, Me.(COLUMN)70(COLUMN)52 Portland, Ore.(COLUMN)78(COLUMN)61 Providence(COLUMN)75(COLUMN)59 Raleigh(COLUMN)82(COLUMN)59 Rapid City(COLUMN)84(COLUMN)58 Reno(COLUMN)93(COLUMN)58 RIchmond(COLUMN)91(COLUMN)61 St. Louis(COLUMN)82(COLUMN)63 St. Prbg-Tampa(COLUMN)91(COLUMN)60 Salt Lake City(COLUMN)86(COLUMN)62 San Antonio(COLUMN)94(COLUMN)74 San Diego(COLUMN)79(COLUMN)10 San Francisco(COLUMN)66(COLUMN)56 San Juan, P.R.(COLUMN)80(COLUMN)76 St. Ste Marie(COLUMN)60(COLUMN)38 Seattle(COLUMN)73(COLUMN)57 Shreveport(COLUMN)89(COLUMN)71 Sioux Falls(COLUMN)78(COLUMN)51 Spokane(COLUMN)97(COLUMN)61 Syracuse(COLUMN)79(COLUMN)50 Topeka(COLUMN)80(COLUMN)69 Tucson(COLUMN)99(COLUMN)71 Tulsa(COLUMN)78(COLUMN)60 Washington(COLUMN)80(COLUMN)61 Wichita(COLUMN)71(COLUMN)67(END TABLE) Temperatures Abroad Yesterday(TABLE) City(COLUMN)Weather(COLUMN)Time(COLUMN)Temp. Aberdeen(COLUMN)cloudy(COLUMN)1 p.m.(COLUMN)59 Amsterdam(COLUMN)cloudy(COLUMN)1 p.m.(COLUMN)63 Ankara(COLUMN)clear(COLUMN)3 p.m.(COLUMN)90 Athens(COLUMN)clear(COLUMN)2 p.m.(COLUMN)91 Auckland(COLUMN)cloudy(COLUMN)midnight(COLUMN)48 Berlin(COLUMN)drizzle(COLUMN)1 p.m.(COLUMN)57 Birmingham(COLUMN)cloudy(COLUMN)1 p.m.(COLUMN)63 Brussels(COLUMN)pt. cldy(COLUMN)1 p.m.(COLUMN)64 Cairo(COLUMN)clear(COLUMN)2 p.m.(COLUMN)93 Casablanca(COLUMN)clear(COLUMN)noon(COLUMN)75 Copenhagan(COLUMN)pt. cldy(COLUMN)1 p.m.(COLUMN)66 Dublin(COLUMN)drizzle(COLUMN)1 p.m.(COLUMN)57 Geneva(COLUMN)cloudy(COLUMN)1 p.m.(COLUMN)64 Hong Kong(COLUMN)cloudy(COLUMN)8 p.m.(COLUMN)86 Lisbon(COLUMN)pt. cldy(COLUMN)noon(COLUMN)72 London(COLUMN)pt. cldy(COLUMN)1 p.m.(COLUMN)64 Madrid(COLUMN)rain(COLUMN)1 p.m.(COLUMN)66 Malta(COLUMN)clear(COLUMN)1 p.m.(COLUMN)64 Manila(COLUMN)rain(COLUMN)8 p.m.(COLUMN)72 Moscow(COLUMN)pt. cldy(COLUMN)3 p.m.(COLUMN)57 New Delhi(COLUMN)pt. cldy(COLUMN)5 p.m.(COLUMN)91 Nice(COLUMN)cloudy(COLUMN)1 p.m.(COLUMN)63 Oslo(COLUMN)rain(COLUMN)1 p.m.(COLUMN)51 Paris(COLUMN)cloudy(COLUMN)1 p.m.(COLUMN)54 Peking(COLUMN)cloudy(COLUMN)1 p.m.(COLUMN)59 Rome(COLUMN)pt. cldy(COLUMN)1 p.m.(COLUMN)81 Saigon(COLUMN)storm(COLUMN)8 p.m.(COLUMN)79 Sofia(COLUMN)pt. cldy(COLUMN)2 p.m.(COLUMN)79 Stockholm(COLUMN)cloudy(COLUMN)1 p.m.(COLUMN)57 Sydney(COLUMN)clear(COLUMN)10 p.m.(COLUMN)57 Tel Aviv(COLUMN)clear(COLUMN)2 p.m.(COLUMN)91 Tokyo(COLUMN)cloudy(COLUMN)9 p.m.(COLUMN)72 Tunis(COLUMN)clear(COLUMN)1 p.m.(COLUMN)91 Vienna(COLUMN)cloudy(COLUMN)1 p.m.(COLUMN)72 Warsaw(COLUMN)pt. cldy(COLUMN)1 p.m.(COLUMN)64(END TABLE) Temperatures (Western Hemisphere)(TABLE) City(COLUMN)Weather(COLUMN)High(COLUMN)Low Acapuclo(COLUMN)pt. cldy(COLUMN)88(COLUMN)77 Barbados(COLUMN)pt. cldy(COLUMN)86(COLUMN)80 Bermuda(COLUMN)pt. cldy(COLUMN)85(COLUMN)74 Calgary(COLUMN)pt. cldy(COLUMN)75(COLUMN)52 Edmonton(COLUMN)clear(COLUMN)73(COLUMN)52 Havana(COLUMN)cloudy(COLUMN)92(COLUMN)77 Kingston(COLUMN)pt. cldy(COLUMN)90(COLUMN)79 Montego Bay(COLUMN)pt. cldy(COLUMN)92(COLUMN)77 Mexico City(COLUMN)haze(COLUMN)75(COLUMN)55(END TABLE)(TABLE) pt. cldy(COLUMN)97(COLUMN)74 Montreal(COLUMN)cloudy(COLUMN)70(COLUMN)54 Nassau(COLUMN)pt. cldy.(COLUMN)90(COLUMN)72 Ottawa(COLUMN)cloudy(COLUMN)68(COLUMN)48 Regina(COLUMN)pt. Cldy(COLUMN)79(COLUMN)50 St. Kitts(COLUMN)cloudy(COLUMN)89(COLUMN)79 St. Thomas(COLUMN)pt. cldy(COLUMN)92(COLUMN)80 Toronto(COLUMN)clear(COLUMN)70(COLUMN)43 Vancouver(COLUMN)clear(COLUMN)75 61 Veracruz(COLUMN)pt. cldy(COLUMN)99(COLUMN)74 Winnipeg(COLUMN)pt. cldy(COLUMN)77(COLUMN)48 (END TABLE)