Washington - Partly cloudy and humid, highs in 90s, lows in 70s. Change of rain is 40 per cent today, 30 per cent tonight. Wednesday - Partly cloudy and humid with chance of afternoon or evening showers, highs in 90s.

Maryland and Virginia: Today and Wednesday - Humid with highs in mid 60s to 70s. Chance of afternoon and evening showers.

Lower Potomac and Chesapeake Bay: Today - Fair skies with chance of afternoon and evening showers with fair to poor visibility through tonight. Winds should be variable at about 5 knots this morning becoming southwesterly at 10 to 15 knots this afternoon and evening.

Extended Area Outlook: For Thursday through Saturday - Slight chance of rain each day with highs in 90s and lows in 70s, Washington's normal temperature should range from low to mid 70s north to upper 70s to near 80 in south.

West Virginia: Today and Wednesday - Humid, highs in mid 80s ato mid 90s, lows tonight in mid 60s to mid 70s. Chance of afternoon or evening showers.

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 105 for the pollutant, photochemical oxidants. Index values between 100 to 200 indicate very unhealthy air quality. When the index exceeds 100 the air becomes hazardous and persons with lung, heart and eye problems should restrict their activity. The National Weather Service forecast's that the Potomac Riverstage at Little Falls will remain near 2.9 feet today.

The National Weather Forecast For Today - Thundershowers will be scattered across the Gulf of Mexico and south Atlantic Coast States through the Tennessee and Upper Ohio Valleys and the lower [WORD ILLEGIBLE] thirds of the Appalachians. Showers will extend over eastern portions of the Dakotas, also from the southern Rockies into East portions of the southern plateau region. Temperatures will be very hot from the middle Missouri Valley across the north half of the Mississippi Valley and Great Lakes through the central Atlantic Coast. Elsewhere temperatures will be unseasonably warm to hot.

Washington data at 8 p.m. (EDT) yesterday: Highest temperature since 8 a.m. yesterday, 92 degrees at 3:50 p.m. Lowest temperature since midnight, 75 degrees at 3:30 a.m. Excess of temperature since July 1, 90 degrees. Excess of temperature since Jan. 1, 296 degrees. Record high temperature for today, 102 degrees in 1930. Record low temperature for today, 56 degrees in 1911. Relative humidity: Maximum, 97 per cent at midnight; Minimum, 58 per cent at 2 p.m. 24 hour precipitation, .24 inches. Excess of precipitation since July 1, .72 inches. Deficiency of precipitation since Jan. 1, 5.70 inches. Highest observed wind since 8 a.m. 15 miles per hour from the N.W. at 1:23 p.m.

ALMANAC DATA FOR July 19, 1977: Sun rises 5:58 a.m., sets 8:30 p.m.; moon rises 9:16 a.m. sets 10:16 p.m. Tides: High 10:44 a.m. and 11:13 p.m., low 5:19 a.m. and 5:42 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); Colinial beach (6); Norfolk (1 1/2); Vorginia Beach (1); Solomons Island (6 1/2); Point Lockout (7); Pollen count: 4 English Plaintain (note: 7 or higher is considered undesirable.) Local Temp., Humidity(TABLE) Time(COLUMN)T(COLUMN)T 12 mid.(COLUMN)78(COLUMN)97 1 a.m.(COLUMN)78(COLUMN)97 2 a.m.(COLUMN)77(COLUMN)88 3 a.m.(COLUMN)76(COLUMN)[WORD ILLEGIBLE] 4 a.m.(COLUMN)75(COLUMN)94 5 a.m.(COLUMN)75(COLUMN)91 6 a.m.(COLUMN)75(COLUMN)91 7 a.m.(COLUMN)76(COLUMN)91 8 a.m.(COLUMN)80(COLUMN)80 9 a.m.(COLUMN)83(COLUMN)70 10 a.m.(COLUMN)85(COLUMN)65 11 a.m.(COLUMN)87(COLUMN)64 12 noon(COLUMN)88(COLUMN)62 1 p.m.(COLUMN)89(COLUMN)60 2p.m.(COLUMN)90(COLUMN)58 3 p.m.(COLUMN)89(COLUMN)64 4 p.m.(COLUMN)92(COLUMN)58 5 p.m.(COLUMN)91(COLUMN)58 6 p.m.(COLUMN)90(COLUMN)58(END TABLE) Temperatures Abroad Yesterday(TABLE) City(COLUMN)Weather(COLUMN)Time(COLUMN)T Aberpeen(COLUMN)cloudy(COLUMN)1 p.m.(COLUMN)54 Amsterdam(COLUMN)cloudy(COLUMN)p.m.(COLUMN)63 Ankara(COLUMN)Pt. cldy(COLUMN)3 p.m.(COLUMN)81 Athens(COLUMN)clear(COLUMN)2 p.m.(COLUMN)88 Auckland(COLUMN)pt. cldy(COLUMN)midnight(COLUMN)55 Berlin(COLUMN)rain(COLUMN)1 p.m.(COLUMN)53 Birmingham(COLUMN)pt. cldy(COLUMN)1 p.m.(COLUMN)64 Byrssels(COLUMN)cloudy(COLUMN)1 p.m.(COLUMN)59 Cairo(COLUMN)clear(COLUMN)2 p.m.(COLUMN)97 Casablanca(COLUMN)pt. cldy(COLUMN)noon(COLUMN)73 Copenhagen(COLUMN)rain(COLUMN)1 p.m.(COLUMN)57 Dublin(COLUMN)drizzle(COLUMN)1 p.m.(COLUMN)57 Geneva(COLUMN)clear(COLUMN)1 p.m.(COLUMN)72 Hong Kong(COLUMN)pt. cldy(COLUMN)8 p.m.(COLUMN)88 Lisbon(COLUMN)clear(COLUMN)noon(COLUMN)75 London(COLUMN)clear(COLUMN)1 p.m.(COLUMN)70 Madrid(COLUMN)clear(COLUMN)1 p.m.(COLUMN)86 Malta(COLUMN)clear(COLUMN)1 p.m.(COLUMN)64 Manila(COLUMN)cloudy(COLUMN)8 p.m.(COLUMN)81 Moscow(COLUMN)pt. cldy(COLUMN)3 p.m.(COLUMN)70 New Dehli(COLUMN)rain(COLUMN)5 p.m.(COLUMN)84 Nice(COLUMN)clear(COLUMN)1 p.m.(COLUMN)75 Oslo(COLUMN)cloudy(COLUMN)1 p.m.(COLUMN)59 Paris(COLUMN)cloudy(COLUMN)1 p.m.(COLUMN)70 Peking(COLUMN)pt. cldy(COLUMN)8 p.m.(COLUMN)84 Rome(COLUMN)clear(COLUMN)1 p.m.(COLUMN)82 Saigon(COLUMN)storm(COLUMN)8 p.m.(COLUMN)75 Sofia(COLUMN)pt. cldy(COLUMN)2 p.m.(COLUMN)73 Stockholm(COLUMN)cloudy(COLUMN)1 p.m.(COLUMN)57 Sydney(COLUMN)pt. cldy(COLUMN)10 p.m.(COLUMN)54 Tel Aviv(COLUMN)clear(COLUMN)2 p.m.(COLUMN)90 Tokyo(COLUMN)clear(COLUMN)9 p.m.(COLUMN)79 Tunis(COLUMN)clear(COLUMN)1 p.m.(COLUMN)90 Viena(COLUMN)pt. cldy(COLUMN)75 Warsaw(COLUMN)cloudy(COLUMN)1 p.m.(COLUMN)64(END TABLE) Temperatures (Western Hemisphere)(TABLE) City(COLUMN)Weather(COLUMN)High(COLUMN)Low Acapulco(COLUMN)sunny(COLUMN)90(COLUMN)81 Barbados(COLUMN)fair(COLUMN)80(COLUMN)80 Bermuda(COLUMN)pt. cldy(COLUMN)86(COLUMN)79 Bogota(COLUMN)cloudy(COLUMN)63(COLUMN)38 Calgary(COLUMN)rain(COLUMN)73(COLUMN)46 Culiacan(COLUMN)pt. cldy(COLUMN)101(COLUMN)77 Edmonton(COLUMN)cloudy(COLUMN)70(COLUMN)48 Havana(COLUMN)cloudy(COLUMN)92(COLUMN)75 Kingston(COLUMN)pt. cldy(COLUMN)90(COLUMN)79 Montego Bay(COLUMN)sunny(COLUMN)88(COLUMN)73 Mexico City(COLUMN)haze(COLUMN)77(COLUMN)58 Monterry(COLUMN)pt. cldy(COLUMN)88(COLUMN)72 Montreal(COLUMN)clear(COLUMN)86(COLUMN)66 Nassau(COLUMN)cloudy(COLUMN)90(COLUMN)77 Ottawa(COLUMN)clear(COLUMN)90(COLUMN)66 Regina(COLUMN)cloudy(COLUMN)84(COLUMN)61 St. Kitta(COLUMN)cloudy(COLUMN)89(COLUMN)78 Toronto(COLUMN)pt. cldy(COLUMN)84(COLUMN)63 Vancouver(COLUMN)clear(COLUMN)66(COLUMN)46 Veracruz(COLUMN)pt. cldy(COLUMN)88(COLUMN)75 Winnipeg(COLUMN)clear(COLUMN)88(COLUMN)64(END TABLE)