Washington: Today - Partly cloudy, high in mid to uppper 70s, low in low to mid 50s. Chance of rain is 20 per cent through tonight. Wednesday - Partly cloudy with chance of rain late in day, highs in mid to upper 70s.

Maryland and Virginia: Today - Partly cloudy, highs in 70s to low 80s, lows ii 50s. Chance of rain in west through tonight. Wednesday - Partly cloudy with chance of rain, high in 70s to low 80s.

Lower Patomac and Chesapeake Bay: Today - Fair skies with good visibility through tonight. Winds should be near 15 knots this afternoon from the south, becoming southwesterly at 10 knots or less tonight.

Estended Area Outlook: For Thursday through Saturday - Humid with chance of afternoon aaand evening showers through period. Highs should be near 80, lows near 60. Washington's normal temperature range for this time of year is from 69 to 48.

Almanac Data for April 19, 1977: Sun rises 5:26 a.m., sets by 6:49 p.m.; moon rises 6:09 a.m., sets 8:08 p.m. Tides: High 8:42 a.m. and 9:05 p.m., low 3:03 a.m. and 3:54 p.m. High and low tides at the following locations can be obtained by subtracting the hours indicated from the lides 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).

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 75 for the pollutant, photochemical oxidants. Index values between 75 and 99 indicate unhealthy air quality. When the index exceeds 100 the air becomes hazardous and persons will lung, heart and eye problems should restrict their activity. The forecast for today indicates the air quality will improve slightly.

The National Weather Service forecasts that the Potomac River stage at Little Falls will fall to 4.0 feet by this morning.

Washington data at 7 p.m. (EST) yesterday: Highest temperature since 7 a.m. yesterday, 79 degrees at 2:40 p.m. Lowest temperature since midnight, 50 degrees at 4:40 a.m. Excess of temperature since April 1, 64 degrees. Excess of temperature since Jan. 1, 45 degrees. Record high temperature for today, 93 degrees in 1976. Record low temperature for today, 22 degrees in 1876. Relative humidity: Maximum, 74 per cent at 5 a.m.; Minimum, 31 per cent at 4 p.m. 24-hour precipitation, none. Deficiency of precipitation since April 1, 46 inch. Deficiency of precipitation since Jan. 1, 4.53 inches. Highest observed wind since 7 a.m. 13 miles per hour from the south at 11:53 a.m. Peak aust since 7 a.m., 21 miles per hour from the S.W. at 10:24 a.m. Local Temp., Humidity(TABLE) Time(COLUMN)T.(COLUMN)H. 12 mid(COLUMN)57(COLUMN)53 1 a.m.(COLUMN)56(COLUMN)55 2 a.m.(COLUMN)55(COLUMN)62 3 a.m.(COLUMN)53(COLUMN)69 4 a.m.(COLUMN)52(COLUMN)69 5 a.m.(COLUMN)50(COLUMN)74 6 a.m.(COLUMN)51(COLUMN)71 7 a.m.(COLUMN)53(COLUMN)69 8 a.m.(COLUMN)59(COLUMN)53 9 a.m.(COLUMN)65(COLUMN)43 10 a.m.(COLUMN)67(COLUMN)44 11 a.m.(COLUMN)72(COLUMN)33 12 noon(COLUMN)74(COLUMN)37 1 p.m.(COLUMN)76(COLUMN)37 2 p.m.(COLUMN)78(COLUMN)34 3 p.m.(COLUMN)79(COLUMN)33 4 p.m.(COLUMN)78(COLUMN)31 5 p.m.(COLUMN)78(COLUMN)34 6 p.m.(COLUMN)77(COLUMN)32(END TABLE) Temperatures ending 7 a.m. (EST) yesterday:(TABLE) City(COLUMN)H(COLUMN)L Albany(COLUMN)68(COLUMN)32 Albuquerque(COLUMN)77(COLUMN)47 Amarillo(COLUMN)63(COLUMN)51 Anchorage(COLUMN)39(COLUMN)27 Asheville(COLUMN)81(COLUMN)47 Atlanta(COLUMN)85(COLUMN)56 Atlantic City(COLUMN)60(COLUMN)45 Austin(COLUMN)74(COLUMN)42 Baltimore(COLUMN)74(COLUMN)42 Billings(COLUMN)54(COLUMN)25 Burlington, Vt.(COLUMN)62(COLUMN)32 Blsmarck(COLUMN)67(COLUMN)47 Boise(COLUMN)57(COLUMN)23 Boston(COLUMN)59(COLUMN)48 Brownsville(COLUMN)75(COLUMN)65 Buffalo(COLUMN)67(COLUMN)48 Burlington, Vt.(COLUMN)62(COLUMN)32 Casper(COLUMN)60(COLUMN)30 Charlton, S.C.(COLUMN)78(COLUMN)65 ch'lton, WVa(COLUMN)79(COLUMN)54 Charlotte, N.C.(COLUMN)82(COLUMN)55 Cheyenne(COLUMN)60(COLUMN)30 Chicago(COLUMN)85(COLUMN)59 Cincianati(COLUMN)79(COLUMN)52 Cleveland(COLUMN)71(COLUMN)52 Columbia, S.C.(COLUMN)88(COLUMN)56 Colu'bus, Ohio(COLUMN)76(COLUMN)52 Dal. Ft. Worth(COLUMN)76(COLUMN)61 Dayton(COLUMN)80(COLUMN)56 Denver(COLUMN)68(COLUMN)41 Des Moines(COLUMN)84(COLUMN)54 Detriot(COLUMN)67(COLUMN)46 Duluth(COLUMN)64(COLUMN)43 El Paso(COLUMN)81(COLUMN)52 Fairbanks(COLUMN)40(COLUMN)24 Fargo(COLUMN)81(COLUMN)49 Flagstaff(COLUMN)71(COLUMN)31 Great Falls(COLUMN)50(COLUMN)23 Hartford(COLUMN)67(COLUMN)37 HELEna(COLUMN)53(COLUMN)23 Honolulu(COLUMN)82(COLUMN)71 Houston(COLUMN)78(COLUMN)66 Indianapolis(COLUMN)85(COLUMN)58 Jackson, Miss.(COLUMN)84(COLUMN)62 Jacksonville(COLUMN)87(COLUMN)54 Juneau(COLUMN)44(COLUMN)35 Kansas City(COLUMN)78(COLUMN)56 Las Vegas(COLUMN)90(COLUMN)60 Little Rock(COLUMN)85(COLUMN)59 Los Angeles(COLUMN)73(COLUMN)57 Louisville(COLUMN)85(COLUMN)58 Memphis(COLUMN)87(COLUMN)66 Midland(COLUMN)72(COLUMN)48 Mitwaukee(COLUMN)63(COLUMN)44 Mpls. St. Paul(COLUMN)66(COLUMN)57 Nashville(COLUMN)87(COLUMN)63 New Orleans(COLUMN)81(COLUMN)67 New York(COLUMN)71(COLUMN)48 Norfolk(COLUMN)68(COLUMN)48 North Platte(COLUMN)69(COLUMN)53 Okla. City(COLUMN)73(COLUMN)57 Omaha(COLUMN)80(COLUMN)56 Oriando(COLUMN)87(COLUMN)58 Philadelphia(COLUMN)75(COLUMN)46 Phoenix(COLUMN)93(COLUMN)63 Pittsburgh(COLUMN)71(COLUMN)42 Portland, Me.(COLUMN)59(COLUMN)31 Portland, Ore.(COLUMN)57(COLUMN)38 Providence(COLUMN)65(COLUMN)43 Raleigh(COLUMN)81(COLUMN)54 Rapid City(COLUMN)64(COLUMN)42 Reno(COLUMN)65(COLUMN)28 Richmond(COLUMN)78(COLUMN)48 St. Louis(COLUMN)88(COLUMN)57 St. Prbg-Tam(COLUMN)87(COLUMN)62 Salt Lake City(COLUMN)63(COLUMN)44 San Antonio(COLUMN)77(COLUMN)53 san Diego(COLUMN)66(COLUMN)58 San Fran.(COLUMN)67(COLUMN)51 San Juan, P.R.(COLUMN)94(COLUMN)76 St. Ste. Marie(COLUMN)67(COLUMN)44 Seattle(COLUMN)55(COLUMN)38 Shreveport(COLUMN)80(COLUMN)59 Sioux Falls(COLUMN)72(COLUMN)62 Spokane(COLUMN)53(COLUMN)28 Syracuse(COLUMN)64 35 Topeka(COLUMN)76(COLUMN)57 Tuscon(COLUMN)85(COLUMN)58 Tulsa(COLUMN)73(COLUMN)60 Washington(COLUMN)75(COLUMN)50 Wichita(COLUMN)73(COLUMN)58(END TABLE) Temperatures Abroad Yesterday(TABLE) City(COLUMN)Weather(COLUMN)Time(COLUMN)Temp. Aberdeen(COLUMN)pt. cldy(COLUMN)1 p.m.(COLUMN)43 Amsterdam(COLUMN)pt. cldy(COLUMN)1 p.m.(COLUMN)45 Ankara(COLUMN)pt cldy(COLUMN)3 p.m.(COLUMN)46 Athens(COLUMN)clear(COLUMN)2 p.m.(COLUMN)63 Auckland(COLUMN)pt cldy(COLUMN)midn't(COLUMN)61 Berlin(COLUMN)pt cldy(COLUMN)1 p.m.(COLUMN)45 Birmingham(COLUMN)cloudy(COLUMN)1 p.m.(COLUMN)43 Brussels(COLUMN)pt cldy(COLUMN)1 p.m.(COLUMN)43 Catro(COLUMN)clear(COLUMN)2 p.m.(COLUMN)77 Casablanca(COLUMN)pt cldy(COLUMN)noon(COLUMN)64 Copenhagen(COLUMN)pt cldy(COLUMN)1 p.m.(COLUMN)41 Dublin(COLUMN)rain(COLUMN)1 p.m.(COLUMN)43 Geneva(COLUMN)clear(COLUMN)1 p.m.(COLUMN)59 Hong Kong(COLUMN)cloudy(COLUMN)8 p.m.(COLUMN)72 Lisbon(COLUMN)clear(COLUMN)noon(COLUMN)63 Lordon(COLUMN)cluidy(COLUMN)1 p.m.(COLUMN)63 London(COLUMN)cloudy(COLUMN)1 p.m.(COLUMN)46 Madrid(COLUMN)pt. cldy(COLUMN)1 p.m.(COLUMN)54 Malta(COLUMN)clear(COLUMN)1 p.m.(COLUMN)61 Manila(COLUMN)clear(COLUMN)8 p.m.(COLUMN)84 Moscow(COLUMN)cloudy(COLUMN)3 p.m.(COLUMN)57 New Delhi(COLUMN)clear(COLUMN)5 p.m.(COLUMN)88 Nice(COLUMN)pt. cldy(COLUMN)61 Oslo(COLUMN)pt. cldy(COLUMN)1 p.m.(COLUMN)45 Paris(COLUMN)cloudy(COLUMN)1 p.m.(COLUMN)50 Peking(COLUMN)clear(COLUMN)8 p.m.(COLUMN)68 Rome(COLUMN)pt. cldy(COLUMN)1 p.m.(COLUMN)63 Saigon(COLUMN)clear(COLUMN)8 p.m.(COLUMN)84 Sofia(COLUMN)clear(COLUMN)2 p.m.(COLUMN)52 Stockholm(COLUMN)pt. cldy(COLUMN)1 p.m.(COLUMN)41 Sydney(COLUMN)clear(COLUMN)10 p.m.(COLUMN)72 Tel Aviv(COLUMN)clear(COLUMN)2 p.m.(COLUMN)68 Tokyo(COLUMN)pt. cldy(COLUMN)9 p.m.(COLUMN)57 Tunis(COLUMN)cloudy(COLUMN)1 p.m.(COLUMN)63 Vienna(COLUMN)pt. cldy(COLUMN)1 p.m.(COLUMN)64 Warsaw(COLUMN)cloudy(COLUMN)1 p.m.(COLUMN)46(END TABLE) Temperature (Western Hemisphere)(TABLE) City(COLUMN)Weather(COLUMN)High(COLUMN)Low Acapulco(COLUMN)sunny(COLUMN)90(COLUMN)70 Barbados(COLUMN)pt. cldy(COLUMN)84(COLUMN)79 Bermuda(COLUMN)pt. cldy(COLUMN)70(COLUMN)59 Calgary(COLUMN)pt. cldy(COLUMN)48(COLUMN)21 Culican(COLUMN)cloudy(COLUMN)91(COLUMN)61 Edmonton(COLUMN)clear(COLUMN)52(COLUMN)21 Havana(COLUMN)pt. cldy(COLUMN)82(COLUMN)68 Kingston(COLUMN)pt. cldy HMontego Bay(COLUMN)sunny(COLUMN)86(COLUMN)75 Mexico City(COLUMN)sunny(COLUMN)77(COLUMN)50 Monterrey(COLUMN)pt. cldy(COLUMN)79(COLUMN)61 Montreal(COLUMN)pt. cldy(COLUMN)63(COLUMN)34 Ottawa(COLUMN)pt. cldy(COLUMN)64(COLUMN)36 Regina(COLUMN)clear(COLUMN)59(COLUMN)28 St. Kitts(COLUMN)cloudy(COLUMN)88(COLUMN)74 St. Thomas(COLUMN)pt. cldy(COLUMN)85(COLUMN)74 Toronto(COLUMN)cloudy(COLUMN)63(COLUMN)39 Cancouver(COLUMN)rain(COLUMN)50(COLUMN)41 Veracruz(COLUMN)pt. cldy(COLUMN)86(COLUMN)73 Winnipeg(COLUMN)cloudy(COLUMN)79(COLUMN)46(END TABLE)