Washington: Today - Rain, high near 70, low near 50. Chance of rain, 80 per cent today, 40 per cent tonight. Monday - Partly cloudy, high in low 60s.

Maryland and Virginia: Today - Rain, highs in 60s to mid 70s, lows in low 40s to mid 50s. Monday - Partly cloudy with chance of rain, highs in upper 50s to mid 60s.

Lower Potomac and Chesapeake Bay: Today - Rain, visibility ranging from good to poor. Winds should be southwesterly at 15 to 25 knots this morning, becoming westerly this afternoon at 15 to 25 knots and decreasing to 10 to 20 knots tonight.

Extended Area Outlook: For Tuesday through Thursday - Partly cloudy, skies through period with chance of rain, Thursday. Highs should average in 60s to low 70s, lows in 40s to near 50. Washington's normal temperature range for this time of year is from 71 to 49.

The National Weather Forecast for Today - Showers and occasional thunderstorms will extend from the Tennessee and Ohio Valley eastward through the Atlantic coastal states from Florida to northern Maine. Elsewhere, skies will be sunny or mostly sunny. Temperatures will be cool from the Plains through the Mississippi Valley and eastward over the Appalachians across New England. It will be warm over the Pacific Coast states and mild over the intermountain region and the Rockies.

Almanac data for April 24, 1977: Sun rises 6:20 a.m., sets 7:54 p.m.; moon rises 10:48 a.m.

Tides: High 12:43 p.m., low 7:10 a.m. and 7:55 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 Lightbouse (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).

The Council of Governments' Air Quality Index for yesterday showed the high reading in the Washington area during the 9 to 10 a.m. period was 28 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 remain about the same.

The National Weather Service forecasts that the Potomac River stage at Little Falls will remain near 3.9 feet through Tuesday. Local Temp., Humidity(TABLE) Time(COLUMN)T.(COLUMN)H. 12 mid.(COLUMN)73(COLUMN)69 1 a.m.(COLUMN)72(COLUMN)71 2 a.m.(COLUMN)72(COLUMN)73 3 a.m.(COLUMN)71(COLUMN)76 4 a.m.(COLUMN)70(COLUMN)76 5 a.m.(COLUMN)69(COLUMN)81 6 a.m.(COLUMN)68(COLUMN)84 7 a.m.(COLUMN)69(COLUMN)81 8 a.m.(COLUMN)71(COLUMN)76 9 a.m.(COLUMN)73(COLUMN)71 10 a.m.(COLUMN)76(COLUMN)69 11 a.m.(COLUMN)78(COLUMN)67 12 noon(COLUMN)80(COLUMN)60 1 p.m.(COLUMN)79(COLUMN)60 2 p.m.(COLUMN)80(COLUMN)56 3 p.m.(COLUMN)79(COLUMN)58 4 p.m.(COLUMN)79(COLUMN)56 5 p.m.(COLUMN)79(COLUMN)56(END TABLE) Temperatures ending 7 a.m. (EST) yesterday:(TABLE) City(COLUMN)H.(COLUMN)L. Albany(COLUMN)83(COLUMN)48 Albuquerque(COLUMN)74(COLUMN)48 Amarillo(COLUMN)63(COLUMN)40 Anchorage(COLUMN)48(COLUMN)33 Asheville(COLUMN)74(COLUMN)59 Atlanta(COLUMN)72(COLUMN)61 Atlantic City(COLUMN)68(COLUMN)57 Austin(COLUMN)78(COLUMN)55 Baltimore(COLUMN)88(COLUMN)67 Billings(COLUMN)75(COLUMN)41 Birmingham(COLUMN)70(COLUMN)65 Bismarck(COLUMN)71(COLUMN)33 Boise(COLUMN)85(COLUMN)56 Boston(COLUMN)88(COLUMN)51 Brownsville(COLUMN)83(COLUMN)59 Buffalo(COLUMN)66(COLUMN)45 Burlington, Vt.(COLUMN)72(COLUMN)47 Casper(COLUMN)71(COLUMN)32 Charleston, S.C.(COLUMN)80(COLUMN)68 Ch'leston, W.V.(COLUMN)74(COLUMN)62 Charlotte, N.C.(COLUMN)80(COLUMN)60 Cheyenne(COLUMN)68(COLUMN)36 Chicago(COLUMN)52(COLUMN)48 Cincinnati(COLUMN)68(COLUMN)61 Cleveland(COLUMN)67(COLUMN)49 Columbia, S.C.(COLUMN)83(COLUMN)62 Columbus, Ohio(COLUMN)70(COLUMN)61 Dal.-Ft. Worth(COLUMN)70(COLUMN)55 Dayton(COLUMN)68(COLUMN)60 Denver(COLUMN)72(COLUMN)41 Des Moines(COLUMN)65(COLUMN)48 Detroit(COLUMN)66(COLUMN)47 Duluth(COLUMN)59(COLUMN)35 El Paso(COLUMN)80(COLUMN)50 Fairbanks(COLUMN)44(COLUMN)35 Fargo(COLUMN)73(COLUMN)38 Flagstaff(COLUMN)71(COLUMN)33 Great Falls(COLUMN)70(COLUMN)36 Hartford(COLUMN)90(COLUMN)63 Helena(COLUMN)73(COLUMN)35 Honolulu(COLUMN)83(COLUMN)69 Houston(COLUMN)79(COLUMN)61 Indianapolis(COLUMN)67(COLUMN)53 Jackson, Miss(COLUMN)80(COLUMN)62 Jacksonville(COLUMN)84(COLUMN)68 Juneau(COLUMN)62(COLUMN)41 Kansas City(COLUMN)57(COLUMN)51 Las Vegas(COLUMN)88(COLUMN)58 Little Rock(COLUMN)77(COLUMN)55 Los Angeles(COLUMN)85(COLUMN)60 Louisville(COLUMN)69(COLUMN)63 Memphis(COLUMN)79(COLUMN)61 Miami Beach(COLUMN)80(COLUMN)75 Midland(COLUMN)75(COLUMN)49 Milwaukee(COLUMN)51(COLUMN)40 Mpls.-St. Paul(COLUMN)67(COLUMN)48 Nashville(COLUMN)71(COLUMN)63 New Orleans(COLUMN)81(COLUMN)65 New York(COLUMN)83(COLUMN)69 Norfolk(COLUMN)86(COLUMN)63 North Platte(COLUMN)66(COLUMN)31 Oklahoma City(COLUMN)59(COLUMN)50 Omaha(COLUMN)69(COLUMN)43 Orlando(COLUMN)85(COLUMN)68 Philadelphia(COLUMN)87(COLUMN)68 Phoenix(COLUMN)95(COLUMN)72 Pittsburgh(COLUMN)71(COLUMN)58 Portland, Me.(COLUMN)82(COLUMN)46 Portland, Ore.(COLUMN)79(COLUMN)48 Providence(COLUMN)86(COLUMN)56 Raleigh(COLUMN)81(COLUMN)60 Rapid City(COLUMN)74(COLUMN)44 Reno(COLUMN)79(COLUMN)38 Richmond(COLUMN)87(COLUMN)65 St. Louis(COLUMN)64(COLUMN)50 St. Prbg.-T'mpa(COLUMN)89(COLUMN)72 Salt Lake City(COLUMN)79(COLUMN)44 San Antonio(COLUMN)80(COLUMN)54 San Diego(COLUMN)75(COLUMN)57 San Francisco(COLUMN)69(COLUMN)49 San Juan, P.R.(COLUMN)85(COLUMN)77 St. Ste. Marie(COLUMN)59(COLUMN)33 Seattle(COLUMN)78(COLUMN)51 Shreveport(COLUMN)78(COLUMN)51 Sioux Falls(COLUMN)68(COLUMN)41 Spokane(COLUMN)77(COLUMN)54 Syracuse(COLUMN)74(COLUMN)52 Topeka(COLUMN)60(COLUMN)50 Tucson(COLUMN)88(COLUMN)62 Tulsa(COLUMN)66(COLUMN)55 Washington(COLUMN)85(COLUMN)68 Wichita(COLUMN)64(COLUMN)52(END TABLE) Temperatures Abroad Yesterday(TABLE) City(COLUMN)Weather(COLUMN)Time(COLUMN)Temp. Aberdeen(COLUMN)rain(COLUMN)1 p.m.(COLUMN)50 Amsterdam(COLUMN)pt. cldy(COLUMN)1 p.m.(COLUMN)54 Ankara(COLUMN)cloudy(COLUMN)3 p.m.(COLUMN)45 Athens(COLUMN)clear(COLUMN)2 p.m.(COLUMN)68 Auckland(COLUMN)clear(COLUMN)midnight(COLUMN)54 Berlin(COLUMN)rain(COLUMN)1 p.m.(COLUMN)57 B'ham(COLUMN)pt. cldy(COLUMN)1 p.m.(COLUMN)54 Brussels(COLUMN)cloudy(COLUMN)1 p.m.(COLUMN)54 Cairo(COLUMN)dust(COLUMN)2 p.m.(COLUMN)70 Casablanca(COLUMN)clear(COLUMN)noon(COLUMN)68 Copenhagen(COLUMN)rain(COLUMN)1 p.m.(COLUMN)48 Dublia(COLUMN)cloudy(COLUMN)1 p.m.(COLUMN)48 Geneva(COLUMN)rain(COLUMN)1 p.m.(COLUMN)59 Hong Kong(COLUMN)pt. cldy(COLUMN)8 p.m.(COLUMN)79 Lisbon(COLUMN)pt. cldy(COLUMN)noon(COLUMN)68 London(COLUMN)pt. cldy(COLUMN)1 p.m.(COLUMN)55 Madrid(COLUMN)pt. cldy(COLUMN)1 p.m.(COLUMN)75 Malta(COLUMN)clear(COLUMN)1 p.m.(COLUMN)66 Manila(COLUMN)pt. cldy(COLUMN)8 p.m.(COLUMN)84 Moscow(COLUMN)cloudy(COLUMN)3 p.m.(COLUMN)50 New Delhi(COLUMN)cloudy(COLUMN)5 p.m.(COLUMN)100 Nice(COLUMN)pt. cldy(COLUMN)1 p.m.(COLUMN)61 Oslo(COLUMN)pt. cldy(COLUMN)1 p.m.(COLUMN)52 Paris(COLUMN)rain(COLUMN)1 p.m.(COLUMN)59 Peking(COLUMN)cloudy(COLUMN)8 p.m.(COLUMN)70 Rome(COLUMN)clear(COLUMN)1 p.m.(COLUMN)66 Saigon(COLUMN)clear(COLUMN)8 p.m.(COLUMN)82 Sofia(COLUMN)clear(COLUMN)2 p.m.(COLUMN)63 Stockholm(COLUMN)pt. cldy(COLUMN)1 p.m.(COLUMN)52 Sydney(COLUMN)pt. cldy(COLUMN)10 p.m.(COLUMN)64 Tel Aviv(COLUMN)cloudy(COLUMN)2 p.m.(COLUMN)64 Tokyo(COLUMN)clear(COLUMN)9 p.m.(COLUMN)66 Tunis(COLUMN)clear(COLUMN)1 p.m.(COLUMN)73 Vienna(COLUMN)rain(COLUMN)1 p.m.(COLUMN)61 Warsaw(COLUMN)cloudy(COLUMN)1 p.m.(COLUMN)55(END TABLE) Temperatures (Western Hemisphere)(TABLE) City(COLUMN)Weather(COLUMN)High(COLUMN)Low Acapulco(COLUMN)clear(COLUMN)88(COLUMN)73 Barbados(COLUMN)pt. cldy(COLUMN)84(COLUMN)75 Bermuda(COLUMN)clear(COLUMN)72(COLUMN)58 Calgary(COLUMN)clear(COLUMN)64(COLUMN)34 Culiacan(COLUMN)fair(COLUMN)95(COLUMN)65 Edmonton(COLUMN)clear(COLUMN)63(COLUMN)34 Havana(COLUMN)cloudy(COLUMN)86(COLUMN)73 Kingston(COLUMN)cloudy(COLUMN)86(COLUMN)75 Montego Bay(COLUMN)clear(COLUMN)84(COLUMN)73 Mexico City(COLUMN)cloudy(COLUMN)73(COLUMN)50 Monterrey(COLUMN)fair(COLUMN)82(COLUMN)59 Montreal(COLUMN)cloudy(COLUMN)64(COLUMN)45 Nassau(COLUMN)pt. cldy(COLUMN)82(COLUMN)66 Ottawa(COLUMN)cloudy(COLUMN)66(COLUMN)45 Regina(COLUMN)clear(COLUMN)66(COLUMN)23 St. Kitts(COLUMN)pt. cldy(COLUMN)80(COLUMN)69 St. Thomas(COLUMN)pt. cldy(COLUMN)80(COLUMN)70 Vancouver(COLUMN)cloudy(COLUMN)64(COLUMN)46 Veracruz(COLUMN)sunny(COLUMN)86(COLUMN)69 Winnipeg(COLUMN)clear(COLUMN)54(COLUMN)30(END TABLE)