Washington: Today - Partly cloudy, high near 80; low in mid to under 50s. Chance of rain is 30 per cent today, 40 per cent night. Saturday - Partly cloudy with chance of rain, high near 80.

Maryland and Virginia: Today - Humid, highs in 70s to low 80s, lows in mid to upper 50s. Chance of afternoon or evening showers, Saturday - Humid with chance of rain, highs in 70s to low 80s.

Lower Potomac and Chesapeake Bay: Today - Chance of rain, mainly in afternoon and evening, with good visibility today and poor visibility late today and tonight. Winds should be southerly at about 10 knots today, becoming southwesterly at less than 10 knots tonight.

Extended Area Outlook: For Sunday through Tuesday - Partly cloudy skies with periods of showers likely through period. Highs should average in 70s, lows in 50s through period. Washington's normal temperature range for this time of year is from 71 to 49.

The National Weather Forecast for Today - Showers and occasional thundershowers will extend from eastern Texas northward throughout the lower Mississippi and the Ohio Valley through the lower Great Lakes and New England and eastward across the south and mid-Atlantic Coast states. The rest of the nation will have sunny or mostly sunny skies.Mild temperatures will continue from the Appalachians through the Atlantic Coast states and from the Rockies to the west coast. It will be cooler over most of the Great Lakes. Elsewhere, near seasonal temperatures will prevail.

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 40 for the pollutant, photochemical oxidants. Index values between 25 and 49 indicate fair air quality. When the index exceeds 100 the air becomes hazardous and persons with lung, heart and eye problems should restrict their activity. The forecast for today indicates the air quality will improve.

The National Weather Service forecasts that the Potomac River stage at Little Falls will remain near 3.9 feet through this morning.

Washington data of 7 p.m. (EST) yesterday: Highest temperature since 7 a.m. yesterday, 80 degrees at 3:30 p.m. Lowest temperature since midnihgt, 55 degrees at 3:30 a.m. Excess of temperatures since April 1, 93 degrees. Excess of temperature since Jan. 1, 74 degrees. Record high temperature for today, 89 degrees in 1972. Record low temperature for today, 30 degrees in 1875. Relative humidity: Maximum, 96 per cent at 5 a.m.; Minimum, 60 per cent at 11:53 a.m. 24 hour precipitates, none. Deficiency of precipitation since April 1, 73 inches. Deficiency of precipitation since Jan. 1, 4.00 inches. Highest observed wind since 7 a.m. 12 miles per hour from the south at 2 p.m. Peak gust since 7 a.m., 16 miles per hour from the S.W. at 12:30 p.m.(TABLE) Time(COLUMN)T.(COLUMN)H. 12 mid.(COLUMN)60(COLUMN)78 1 a.m.(COLUMN)59(COLUMN)83 2 a.m.(COLUMN)57(COLUMN)90 3 a.m.(COLUMN)57(COLUMN)90 4 a.m.(COLUMN)57(COLUMN)93 5 a.m.(COLUMN)56(COLUMN)96 6 a.m.(COLUMN)56(COLUMN)96 7 a.m.(COLUMN)58(COLUMN)93 8 a.m.(COLUMN)61(COLUMN)84 9 a.m.(COLUMN)65(COLUMN)78 10 a.m.(COLUMN)68(COLUMN)63 11 a.m.(COLUMN)73(COLUMN)62 12 a.m.(COLUMN)75(COLUMN)60 1 p.m.(COLUMN)77(COLUMN)62 2 p.m.(COLUMN)79(COLUMN)60 3 p.m.(COLUMN)79(COLUMN)60 4 p.m.(COLUMN)78(COLUMN)62 5 p.m.(COLUMN)78(COLUMN)62 6 p.m.(COLUMN)76(COLUMN)69(END TABLE) Temperatures ending 7 a.m. (EST) yesterday:(TABLE) City(COLUMN)H.(COLUMN)L. Albany(COLUMN)70(COLUMN)52 Albuquerque(COLUMN)57(COLUMN)39 Amarillo(COLUMN)57(COLUMN)42 Anchorage(COLUMN)48(COLUMN)42 Asheville(COLUMN)75(COLUMN)56 Atlanta(COLUMN)77(COLUMN)59 Atlantic City(COLUMN)58(COLUMN)49 Austin(COLUMN)74(COLUMN)60 Baltimore(COLUMN)71(COLUMN)48 Billings(COLUMN)52(COLUMN)27 Birmingham(COLUMN)83(COLUMN)69 Bismarck(COLUMN)58(COLUMN)32 Boise(COLUMN)68(COLUMN)50 Bouston(COLUMN)69(COLUMN)53 Brownsville(COLUMN)90(COLUMN)71 Buffalo(COLUMN)79(COLUMN)61 Burlington, Vt.(COLUMN)74(COLUMN)60 Casper(COLUMN)80(COLUMN)32 Charlton, S.C.(COLUMN)80(COLUMN)69 Charltn, W.Va.(COLUMN)84(COLUMN)69 Charlotte, N.C.(COLUMN)80(COLUMN)58 Cheyenne(COLUMN)50(COLUMN)30 Chicago(COLUMN)81(COLUMN)59 Cincinnati(COLUMN)80(COLUMN)61 Cleveland(COLUMN)82(COLUMN)61 Columbia, S.C.(COLUMN)85(COLUMN)54 Columbus, Ohio(COLUMN)81(COLUMN)64 Dal. Ft. Worth(COLUMN)75(COLUMN)60 Dayton(COLUMN)81(COLUMN)60 Denver(COLUMN)49(COLUMN)34 Des Moines(COLUMN)79(COLUMN)50 Detroit(COLUMN)79(COLUMN)55 Duluth(COLUMN)49(COLUMN)42 El Paso(COLUMN)71(COLUMN)41 Fairbanks(COLUMN)50(COLUMN)29 Fargo(COLUMN)53(COLUMN)31 Flagstaff(COLUMN)60(COLUMN)22 Great Falls(COLUMN)42(COLUMN)31 Hartford(COLUMN)75(COLUMN)47 Helena(COLUMN)52(COLUMN)30 Honolulu(COLUMN)81(COLUMN)73 Houston(COLUMN)81(COLUMN)64 Indianapolis(COLUMN)79(COLUMN)63 Jackson, Miss(COLUMN)70(COLUMN)66 Jacksonville(COLUMN)80(COLUMN)67 Juneau(COLUMN)50(COLUMN)32 Kansas City(COLUMN)72(COLUMN)53 Las Vegas(COLUMN)82(COLUMN)50 Little Rock(COLUMN)67(COLUMN)64 Los Angeles(COLUMN)80(COLUMN)55 Louisville(COLUMN)83(COLUMN)63 Memphis(COLUMN)79(COLUMN)65 Miami Beach(COLUMN)81(COLUMN)75 Midland(COLUMN)76(COLUMN)46 Milwaukee(COLUMN)69(COLUMN)56 Mpls. St. Paul(COLUMN)58(COLUMN)43 Nashville(COLUMN)85(COLUMN)69 New Orleans(COLUMN)77(COLUMN)66 New York(COLUMN)63(COLUMN)51 Norfolk(COLUMN)68(COLUMN)56 North Platte(COLUMN)45(COLUMN)30 Oklahoma City(COLUMN)75(COLUMN)52 Omaha(COLUMN)71(COLUMN)48 Orlando(COLUMN)85(COLUMN)68 Phildelphia(COLUMN)77(COLUMN)51 Phoenix(COLUMN)86(COLUMN)57 Pittsburgh(COLUMN)80(COLUMN)58 Portland, Me.(COLUMN)50(COLUMN)42 Portland, Ore.(COLUMN)66(COLUMN)50 Providence(COLUMN)62(COLUMN)47 Raleigh(COLUMN)81(COLUMN)61 Rapid City(COLUMN)57(COLUMN)34 Reno(COLUMN)73(COLUMN)31 Richmond(COLUMN)80(COLUMN)52 St. Louis(COLUMN)79(COLUMN)60 St. Prbg.-Tampa(COLUMN)85(COLUMN)69 Salt Lake City(COLUMN)61(COLUMN)34 San Antonio(COLUMN)80(COLUMN)61 San Diego(COLUMN)71(COLUMN)56 San Francisco(COLUMN)55(COLUMN)44 San Juan, P.R.(COLUMN)88(COLUMN)71 St. Ste. Marie(COLUMN)56(COLUMN)50 Seattle(COLUMN)65(COLUMN)53 Shreveport(COLUMN)72(COLUMN)55 Sioux Falls(COLUMN)52(COLUMN)39 Spokane(COLUMN)57(COLUMN)44 Syracuse(COLUMN)78(COLUMN)58 Topeka(COLUMN)73(COLUMN)52 Tucson(COLUMN)77(COLUMN)50 Tulsa(COLUMN)68(COLUMN)58 Washington(COLUMN)75(COLUMN)55 Wilchita(COLUMN)71(COLUMN)48(END TABLE) Temperatures Abroad Yesterday(TABLE) City(COLUMN)Weather(COLUMN)Time(COLUMN)Temp. Aberdeen(COLUMN) cloudy(COLUMN) 1 p.m.(COLUMN) 57 Amsterdam(COLUMN) cloudy(COLUMN) 1 p.m.(COLUMN) 55 Ankara(COLUMN) rain(COLUMN) 3 p.m.(COLUMN) 50 Athens(COLUMN) rain(COLUMN) 2 p.m.(COLUMN) 54 Auckland(COLUMN) clear(COLUMN) midnight(COLUMN) 52 Berlin(COLUMN) drizzle(COLUMN) 1 p.m.(COLUMN) 46 Birmingham(COLUMN) rain(COLUMN) 1 p.m.(COLUMN) 55 Brussels(COLUMN) cloudy(COLUMN) 1 p.m.(COLUMN) 52 Cairo(COLUMN) pt. cldy.(COLUMN) 2 p.m.(COLUMN) 86 Copenhagen(COLUMN) cloudy(COLUMN) 1 p.m.(COLUMN) 46 Dublin(COLUMN) cloudy(COLUMN) 1 p.m.(COLUMN) 55 Geneva(COLUMN) pt. cldy.(COLUMN) 1 p.m.(COLUMN) 57 Hong Kong(COLUMN) cloudy(COLUMN) 1 p.m.(COLUMN) 75 Lisbon(COLUMN) clear(COLUMN) noon(COLUMN) 73 London(COLUMN) cloudy(COLUMN) 1 p.m.(COLUMN) 55 Madrid(COLUMN) clear(COLUMN) 1 p.m.(COLUMN) 66 Malta(COLUMN) rain(COLUMN) 1 p.m.(COLUMN) 57 Manila(COLUMN) clear(COLUMN) 8 p.m.(COLUMN) 82 Moscow(COLUMN) pt. cldy.(COLUMN) 3 p.m.(COLUMN) 43 New Delhi(COLUMN) clear(COLUMN) 5 p.m.(COLUMN) 91 Nice(COLUMN) clear(COLUMN) 1 p.m.(COLUMN) 63 Oslo(COLUMN) cloudy(COLUMN) 1 p.m.(COLUMN) 45 Paris(COLUMN) pt. cldy.(COLUMN) 1 p.m.(COLUMN) 61 Peking(COLUMN) clear(COLUMN) 8 p.m.(COLUMN) 61 Rome(COLUMN) clear(COLUMN) 1 p.m.(COLUMN) 68 Saigon(COLUMN) clear(COLUMN) 8 p.m.(COLUMN) 82 Sofia(COLUMN) pt. cldy.(COLUMN) 2 p.m.(COLUMN) 46 Stockholm(COLUMN) cloudy(COLUMN) 1 p.m.(COLUMN) 45 Sydney(COLUMN) pt. cldy.(COLUMN) 10 p.m.(COLUMN) 61 Tel Aviv(COLUMN) cloudy(COLUMN) 2 p.m.(COLUMN) 77 Tokyo(COLUMN) pt. cldy.(COLUMN) 9 p.m.(COLUMN) 55 Tunis(COLUMN) rain(COLUMN) 1 p.m.(COLUMN) 59 Vienna(COLUMN) clear(COLUMN) 1 p.m.(COLUMN) 59 Warsaw(COLUMN) pt. cldy.(COLUMN) 1 p.m.(COLUMN) 75(END TABLE) Temperatures (Western Hemisphere)(TABLE) City(COLUMN)Weather(COLUMN)High(COLUMN)Low Acapulco(COLUMN) cloudy(COLUMN) 28(COLUMN) 72 Barbados(COLUMN) pt. cldy(COLUMN) 82(COLUMN) 77 Bermuda(COLUMN) clear(COLUMN) 69(COLUMN) 61 Bogota(COLUMN) pt. cldy.(COLUMN) 65(COLUMN) 51 Clagary(COLUMN) cloudy(COLUMN) 45(COLUMN) 16 Culiacan(COLUMN) clear(COLUMN) 38(COLUMN) 59 Edmonton(COLUMN) clear(COLUMN) 38(COLUMN) 16 Havana(COLUMN) pt. cldy.(COLUMN) 82(COLUMN) 72 Kingston(COLUMN) cloudy(COLUMN) 88(COLUMN) 76 Montego Bay(COLUMN) clear(COLUMN) 38(COLUMN) 77 Mexico City(COLUMN) cloudy(COLUMN) 63(COLUMN) 53 Monterrey(COLUMN) cloudy(COLUMN) 91(COLUMN) 65 Montreal(COLUMN) cloudy(COLUMN) 75(COLUMN)54 Nassau(COLUMN) clear(COLUMN) 82(COLUMN) 71 Ottawa(COLUMN) cloudy(COLUMN) 75(COLUMN) 57 Regina(COLUMN) pt. cldy.(COLUMN) 50(COLUMN)25 St. Kitts(COLUMN) pt. cldy.(COLUMN) 86(COLUMN) 69 St. Thomas(COLUMN) clear(COLUMN) 85(COLUMN) 71 Toronto(COLUMN) pt. cldy.(COLUMN) 68(COLUMN) 50 Vancouver(COLUMN) cloudy(COLUMN) 54(COLUMN) 41 Veracruz(COLUMN) smoke(COLUMN) 86(COLUMN) 77 Winnipeg(COLUMN) rain(COLUMN) 61(COLUMN) 30(END TABLE).