Washington: Today - partly cloudy, high near 80, low near 60. Chance of rain is 10 per cent today, 20 per cent tonight. Sunday partly cloudy, high near 80.

Maryland and Virginia: Today - partly cloudy, high near 60, low in 50. Chance of rain tonight and Sunday. Sunday - partly cloudy with chance of rain, highs near 80.

Lower Potomac and Chesapeake Bay: Today - partly cloudy skies with variable winds at less than 8 knots throught tonight. Visibility should be 5 miles or more today, decreasing to 2 miles, or less during possible rain tonight.

Extended Area Outlook: For Sunday through Wednesday - partly cloudy skies with chance of rain each day. Highs should average in 80s, lows in 60s. It should be slight cooler in moutains. Washington normal temperature range for this time of year is from 86 to 67.

West Virginia: Today - partly cloudy with chance of rain, highs to 70s, lows in upper 40s to upper 60s. Sunday - partly cloudy, highs in mid 70s to low 80s.

Atlantic Ocean Beaches from Cape May through Maryland: Today - Partly cloudy, high near 80. Sunday - partly cloudy with chance of rain, high near 80. Water temperatures should range from low to mid 70s both days.

Atlantic Ocean Beaches from Cane Hatteras through Virginia: Partly cloudy with chance of rain, high near 80. Sunday - Cloudy with rain spreading, high near 80. Water temperature should be near 80 both days.

The National Weather Forecast for Today Rain and showers will occur in Southern Appalanchians and south Atlantic states through Virginia. Scattered showers and thundershowers can be expected along the Gulf Coast, lower Missippi Valley, central Rockies and eastern portions of the southern Plains. Slightly cooler temperatures are expected from eastern Washington to Dakota while inland California through the Great Basin will be warmer. Otherwise, little change from yesterday.

Almanac Data for Aug. 20, 1977: Sun, rises 6:26 a.m., sets 7:55 p.m., moon rises 12:28 p.m., sets 11:21 p..m. Tides: High 12:38 p.m. and low 7:12 a.m. and 7:15 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 Peach (6); Norfolk (1 1/2); Virginia Beach (1); Solomons Island (6 1/2); Point Lockout (7). Pollen count: 13 Ragweed (note: 7 or higher is considered undesirable.)

The Council of Government's Air Quality Index for yesterday showed the high reading in the Washington Area during the 2 to 3 p.m. period was 75 for the pollutant zone. Index values between 50 and 99 indicate unhealthy air quality. When the index exceeds 110, the air is considered hazardous and individuals with lung, heart and eye ailments are urged to restrict their activity.

The National Weather Service forecasts the Potomac River stage at Little Falls will be near 3 feet today.

Washington data at 8 p.m. (EDT) yesterday: Highest temperature since 8 a.m. yesterday, 80 degrees at 2:25 p.m. Lowest temperature since midnight, 62 degrees at 6:30 a.m. Excess of temperature since Aug. 1, 54 degrees. Excess of temperature since Jan. 1, 331 degrees. Record high temperature for today, 100 degrees in 1874. Record low temperature for today, 50 degrees in 1896. Relative humidity; Maximum, 78 per cent at 7 a.m.; Minimum, 42 per cent at 1 p.m. 24-hour precipitation, none. Excess of precipition since Aug. 1, 15 inches. Deficiency of preciptation since Jan. 1, 6:33 inches. Highest observed wind since 8 a.m. 7 miles per hour from the north at 9:53 a.m. Peak gust since 8 a.m., 12 miles per hour from the South at 3:08 p.m. Local Temp., Humidity

(TABLE) Time(COLUMN)T(COLUMN)73 12 mid.(COLUMN)67(COLUMN)73 1 a.m.(COLUMN)65(COLUMN)75 2 a.m.(COLUMN)64(COLUMN)70 4 a.m.(COLUMN)64(COLUMN)73 5 a.m.(COLUMN)65(COLUMN)68 6 a.m.(COLUMN)63(COLUMN)75 7 a.m.(COLUMN)62(COLUMN)78 8 a.m.(COLUMN)65(COLUMN)68 9 a.m.(COLUMN)68(COLUMN)65 10 a.m.(COLUMN)71(COLUMN)57 11 a.m.(COLUMN)74(COLUMN)52 12 noon(COLUMN)76(COLUMN)45 1 p.m.(COLUMN)77(COLUMN)42 2 p.m.(COLUMN)78(COLUMN)44 3 p.m.(COLUMN)78(COLUMN)47 4 P.m.(COLUMN)79(COLUMN)49 5 p.m.(COLUMN)77(COLUMN)50 6 P.m.(COLUMN)77(COLUMN)52(END TABLE) Temperatures ending 8 a.m. (EDT) yesterday.(TABLE) City(COLUMN)H.(COLUMN)L. Albany(COLUMN)74(COLUMN)43 Albuquerque(COLUMN)86(COLUMN)65 Amarillo(COLUMN)63(COLUMN)71 Anchorage(COLUMN)69(COLUMN)55 Ashville(COLUMN)78(COLUMN)62 Atlanta(COLUMN)85(COLUMN)64 Atlantic City(COLUMN)76(COLUMN)54 Austin(COLUMN)94(COLUMN)75 Baltimore(COLUMN)78(COLUMN)56 Billings(COLUMN)88(COLUMN)60 Birmingham(COLUMN)88(COLUMN)70 Bismarck(COLUMN)83(COLUMN)51 Boise(COLUMN)56(COLUMN)72 Boston(COLUMN)75(COLUMN)56 Brownsville(COLUMN)96(COLUMN)77 Bufflao(COLUMN)63(COLUMN)45 Burlington, Vt.(COLUMN)68(COLUMN)48 Casper(COLUMN)71(COLUMN)53 Charleton, S.C.(COLUMN)90(COLUMN)74 Charl'on W.Va.(COLUMN)75(COLUMN)52 Charlotte, N.C.(COLUMN)75$$(COLUMN)61 Chevenne(COLUMN)66(COLUMN)56 Chicago(COLUMN)71(COLUMN)54 Cinccinati(COLUMN)74(COLUMN)50 Cleveland(COLUMN)66(COLUMN)49 Columbia, S.C.(COLUMN)77(COLUMN)67 Columbus, Ohio(COLUMN)72(COLUMN)49 Del Ft. Worth(COLUMN)90(COLUMN)73 Deyton(COLUMN)74(COLUMN)52 Denver(COLUMN)80(COLUMN)60 Des Moines(COLUMN)74(COLUMN)60 Detroit(COLUMN)74(COLUMN)44 Duluth(COLUMN)69(COLUMN)42 El Paso(COLUMN)96(COLUMN)72 Fairbanks(COLUMN)81(COLUMN)57 Fargo(COLUMN)78 48 Flagstaff(COLUMN)79(COLUMN)52 Great Falls(COLUMN)90(COLUMN)53 Hartford(COLUMN)77(COLUMN)46 Helena(COLUMN)91(COLUMN)58 Honolulu(COLUMN)80(COLUMN)77 Houston(COLUMN)82(COLUMN)79 Indianapolis(COLUMN)76(COLUMN)56 Jackson, Miss(COLUMN)85(COLUMN)73 Jacksonville(COLUMN)95(COLUMN)76 Juneau(COLUMN)79(COLUMN)49 Kansas City(COLUMN)74(COLUMN)61 Lass Vegas(COLUMN)97(COLUMN)75 Little Rock(COLUMN)81(COLUMN)66 Los Angeles(COLUMN)83(COLUMN)69 Louisville(COLUMN)80(COLUMN)59 Memphis(COLUMN)86(COLUMN)66 Miami Beach(COLUMN)87(COLUMN)81 Midland(COLUMN)100(COLUMN)76 Milwaukee(COLUMN)67(COLUMN)50 Mpls. - St. Paul(COLUMN)72(COLUMN)55 Nashville(COLUMN)83(COLUMN)59 New Orleans(COLUMN)89(COLUMN)76 New York(COLUMN)77(COLUMN)59 Norfolk(COLUMN)74(COLUMN)65 North Platte(COLUMN)80(COLUMN)58 Oklahoma City(COLUMN)84(COLUMN)71 Omaha(COLUMN)72(COLUMN)62 Orlando(COLUMN)95(COLUMN)74 Philadelphia(COLUMN)78(COLUMN)56 Phoenix(COLUMN)103(COLUMN)87 Piittsburgh(COLUMN)68(COLUMN)43 Portland, Me(COLUMN)75(COLUMN)46 Portland, Ore(COLUMN)79(COLUMN)63 Providence(COLUMN)75(COLUMN)52 Raleigh(COLUMN)74(COLUMN)58 Rapid City(COLUMN)85 51 Reno(COLUMN)89(COLUMN)53 Richmond(COLUMN)80(COLUMN)61 St. Louis(COLUMN)76(COLUMN)56 St. Prhq.-Tampa(COLUMN)90(COLUMN)77 Salt Lake City(COLUMN)80(COLUMN)63 San Antonio(COLUMN)93(COLUMN)76 San Diego(COLUMN)78(COLUMN)69 San Francisco(COLUMN)66(COLUMN)57 San Juana, P.R.(COLUMN)91(COLUMN)77 ST.Ste. Marie(COLUMN)64(COLUMN)47 Seattle(COLUMN)76(COLUMN)59 Shreveport(COLUMN)78(COLUMN)67 Sioux Falls(COLUMN)70(COLUMN)55 Spokane(COLUMN)100(COLUMN)65 Syracuse(COLUMN)66(COLUMN)46 Topeka(COLUMN)80(COLUMN)64 Tucson(COLUMN)96(COLUMN)79 Tuisa(COLUMN)85(COLUMN)70 Washington(COLUMN)78(COLUMN)62 Wichita(COLUMN)77(COLUMN)62(END TABLE) Temperatures Abroad Yesterday(TABLE) City(COLUMN)WeatherWeather(COLUMN)Time(COLUMN)Temp. Aberdeen(COLUMN)cloudy(COLUMN)1 p.m.(COLUMN)61 Amsterdam(COLUMN)cloudy(COLUMN)1 p.m.(COLUMN)64 Ankara(COLUMN)clear(COLUMN)3 p.m.(COLUMN)81 Athens(COLUMN)clear(COLUMN)2 p.m.(COLUMN)84 Auckland(COLUMN)clear(COLUMN)midnight(COLUMN)52 Berlin(COLUMN)cloudy(COLUMN)1 p.m.(COLUMN)64 Birmingham(COLUMN)drizzle(COLUMN)1 p.m.(COLUMN)54 Brussels(COLUMN)cloudy(COLUMN)1 p.m.(COLUMN)59 Cairo(COLUMN)clear(COLUMN)2 p.m.(COLUMN)91 Casablanca(COLUMN)pt. cldy(COLUMN)noon(COLUMN)73 Brenhagen(COLUMN)cloudy(COLUMN)1 p.m.(COLUMN)63 Dublin(COLUMN)cloudy(COLUMN)1 p.m.(COLUMN)61 Geneva(COLUMN)pt.cldy(COLUMN)1 p.m.(COLUMN)63 Hong Kong(COLUMN)pt.cldy(COLUMN)8 p.m.(COLUMN)84 Lisbon(COLUMN)cloudy(COLUMN)noon(COLUMN)70 London(COLUMN)rain(COLUMN)1 p.m.(COLUMN)57 Madrid(COLUMN)cloudy(COLUMN)1 p.m.(COLUMN)72 Maita(COLUMN)clear(COLUMN)1 p.m.(COLUMN)83 Manila(COLUMN)rain(COLUMN)8 p.m.(COLUMN)77 Moscow(COLUMN)pt.cldy(COLUMN)3 p.m.(COLUMN)52 New Delhi(COLUMN)pt.cldy(COLUMN)5 p.m.(COLUMN)91 Nice(COLUMN)clear(COLUMN)1 p.m.(COLUMN)77 Oslo(COLUMN)cloudy(COLUMN)1 p.m.(COLUMN)59 Paris(COLUMN)cloudy(COLUMN)1 p.m.(COLUMN)64 Peking(COLUMN)cloudy(COLUMN)8 p.m.(COLUMN)75 Rome(COLUMN)pt.cldy(COLUMN)1 p.m.(COLUMN)79 Saigon(COLUMN)storm(COLUMN)8 p.m.(COLUMN)79 Sofia(COLUMN)clear(COLUMN)9 p.m.(COLUMN)79 Stockholm(COLUMN)cloudy(COLUMN)1 p.m.(COLUMN)57 Sydney(COLUMN)clear(COLUMN)10 p.m.(COLUMN)61 Tel Aviv(COLUMN)clear(COLUMN)2 p.m.(COLUMN)83 Tokyo(COLUMN)rain(COLUMN)9 p.m.(COLUMN)70 Tunis(COLUMN)rain(COLUMN)1 p.m.(COLUMN)97 Vienna(COLUMN)cloudy(COLUMN)1 p.m.(COLUMN)66 Warsaw(COLUMN)rain(COLUMN)1 p.m.(COLUMN)55(END TABLE) Temperatures (Western Hemisphere)(TABLE) City(COLUMN)Weather(COLUMN)H.(COLUMN)L. Acapulco(COLUMN)cloudy(COLUMN)90(COLUMN)77 Bermuda(COLUMN)rain(COLUMN)68(COLUMN)77 Bogota(COLUMN)pt.cldy(COLUMN)66(COLUMN)35 Calgary(COLUMN)clear(COLUMN)25(COLUMN) Caliacan(COLUMN)fair(COLUMN)97(COLUMN)77 Edmonton(COLUMN)pt.cldy(COLUMN)75(COLUMN)45 Kingston(COLUMN)cloudy(COLUMN)90(COLUMN)79 Montego Bay(COLUMN)pt.cldy(COLUMN)90(COLUMN)77 Mexico City(COLUMN)pt.cldy(COLUMN)77(COLUMN)54 Monterrey(COLUMN)sunny(COLUMN)95(COLUMN)73 Montreal(COLUMN)clear(COLUMN)66(COLUMN)45 Nassau(COLUMN)pt.cldy(COLUMN)90(COLUMN)73 Ottawa(COLUMN)clear(COLUMN)66(COLUMN)45 Regina(COLUMN)clear(COLUMN)79(COLUMN)45 St. Kitts(COLUMN)pt.cldy(COLUMN)88(COLUMN)79 St. Thomas(COLUMN)fair(COLUMN)90(COLUMN)83 Toronto(COLUMN)clear(COLUMN)66(COLUMN)43 Vancouver(COLUMN)clear(COLUMN)73(COLUMN)57 Veracruz(COLUMN)pt.cldy(COLUMN)90(COLUMN)72 Winnipeg(COLUMN)cloudy(COLUMN)72(COLUMN)45(END TABLE)