Washington: Today - Partly cloudy, high near 90, low in the mid 60s. The chance of rain is 40 per cent today and 10 per cent tonight. Saturday - Sunny, high near 90.

Maryland and Virginia: Today - Chance of thunderstorms, highs from the low 80s to near 90, lows in the 60s. Saturday - Sunny, high from the mid 80s to near 90.

Lower Potomac and Chesapeake Bay: Today - Cloudy, chance of thunderstorms. Wind will be from the southwest at less than 22 knots today, but from the west at from 10 to 15 knots tonight. Waves in unprotected waters will be less than 2 feet. Visibility will be more than 5 miles.

Atlantic Ocean Beaches from Cape May to Cape Hatteras: Today - Chance of thunderstorms, highs from the mid 80s to near 90. Saturday - Sunny, highs in the 80s. Water temperatures will range from the 60s in the north to the 70s elsewhere.

The National Weather Forecast for today - Thunderstorms are likely from the northern and central Appalachians into the northern and middle Atlantic coast. Scattered thunderstorms will fall over the southern Atlantic coast, the southern Appalachians and portions of the Gulf Coast. Some isolated thundershowers may dot the southern Rockies and southwestern plains. Other areas will be clear or partly cloudy. Temperatures will remain generally mild across the north and warm across the South with hot weather in the southwestern interior. It will be warmer from the northern Rockies into the northern and central plains, but a little cooler from the north Atlantic states into the Ohio Valley.

Extended Area Forecast for Sunday through Tuesday: Fair on Sunday, but a chance of thunderstorms on Monday and Tuesday. Highs will be from the low 30s to near 90, lows from the low 60s to near 70. Normal Washington temperatures for the period are a high of 88 and a low of 66.

West Virginia: Today - Rain ending by afternoon, partly cloudy tonight, highs will be from the mid 70s to the mid 80s, lows from the 50s to the low 60s. Saturday - Partly cloudy, highs from the mid 70s to the mid 80s.

Almanac Data for today - July 1, 1977: Sun rises 5:46 a.m., sets 8:37 p.m.; moon rises 8:59 p.m. sets 6:27 a.m. Tides: High 8:51 a.m. and 9:26 p.m. Low 3:05 a.m. and 3:45 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 Beach (6); Norfolk (1 1/2); Virginia Beach (1); Solomons Island (6 1/2); Point Lookout (7). Pollen count: 18 grass (note: more than 7 or higher is considered undesirable.)

The Council of Governments' Air Quality Index for yesterday showed the high reading in the Washington area during the 2 p.m. to 3 p.m. period was 100 for the pollutant, photochemical oxidants. 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 be near 3.1 feet.

Washington data at 8 p.m. (EDT) yesterday: Highest temperature since 8 a.m. yesterday, 91 degrees at 1:30 p.m. Lowest temperature since midnight, 67 degrees at 5:40 a.m. Deficiency of temperature since June 1, 2 degrees. Excess of temperature since Jan. 1, 206 degrees. Record high temperature for today, 102 degrees in 1901. Record low temperature for today, 54 degrees in 1925. Relative humidity: Maximum, 78 per cent at 6 a.m.; Minimum, 37 per cent at 4 p.m. Deficiency of precipitation since June 1, 20 inches. Deficiency of precipitation since Jan. 1, 6.42 inches. Highest observed wind since 8 a.m. 15 miles per hour from the south at 2:53 p.m. Peak gust since 8 a.m., 25 miles per hour from the southwest at 4:29 p.m. Local Temp., Humidity(TABLE) Time(COLUMN)T.(COLUMN)H. 12 mid.(COLUMN)30(COLUMN)49 1 a.m.(COLUMN)78(COLUMN)50 2 a.m.(COLUMN)77(COLUMN)52 3 a.m.(COLUMN)75(COLUMN)56 4 a.m.(COLUMN)73(COLUMN)62 5 a.m.(COLUMN)68(COLUMN)76 6 a.m.(COLUMN)67(COLUMN)78 7 a.m.(COLUMN)71(COLUMN)71 8 a.m.(COLUMN)76(COLUMN)64 9 a.m.(COLUMN)81(COLUMN)53 10 a.m.(COLUMN)83(COLUMN)51 11 a.m.(COLUMN)83(COLUMN)46 12 noon(COLUMN)85(COLUMN)45 1 p.m.(COLUMN)88(COLUMN)39 2 p.m.(COLUMN)89(COLUMN)38 3 p.m.(COLUMN)89(COLUMN)41 4 p.m.(COLUMN)89(COLUMN)32 5 p.m.(COLUMN)90(COLUMN)37 6 p.m.(COLUMN)89(COLUMN)41 7 p.m.(COLUMN)87(COLUMN)48 8 p.m.(COLUMN)85(COLUMN)53 9 p.m.(COLUMN)81(COLUMN)61 10 p.m.(COLUMN)80(COLUMN)65 11 p.m.(COLUMN)80(COLUMN)67(END TABLE) Temperatures ending 8 p.m. (EDT) yesterday(TABLE) City(COLUMN)L.(COLUMN)H. Albany(COLUMN)39(COLUMN) 35 Albuquerque(COLUMN)62(COLUMN) 97 Amarillo(COLUMN)70(COLUMN) 85 Anchorage(COLUMN)41(COLUMN) 38 Asheville(COLUMN)63(COLUMN) 84 Atlanta(COLUMN)69(COLUMN) 93 Atlantic City(COLUMN)66(COLUMN) 80 Austin(COLUMN)76(COLUMN) 93 Baltimore(COLUMN)64(COLUMN) 90 Billings(COLUMN)42(COLUMN) 36 Birmingham(COLUMN)73(COLUMN) 95 Bismarck(COLUMN)41(COLUMN) 37 Boise(COLUMN)42(COLUMN) 35 Boston(COLUMN)38(COLUMN) 35 Brownsville(COLUMN)79(COLUMN) 92 Buffalo(COLUMN)39(COLUMN) 36 Burlington(COLUMN)39(COLUMN) 35 Casper(COLUMN)41(COLUMN) 36 Charleston, S.C.(COLUMN)79(COLUMN) 94 Ch'leston, W.Va.(COLUMN)57(COLUMN) 88 Charlotte(COLUMN)71(COLUMN) 94 Cheyenne(COLUMN)42(COLUMN) 37 Chicago(COLUMN)38(COLUMN) 36 Cincinnati(COLUMN)58(COLUMN) 86 Cleveland(COLUMN)40(COLUMN) 36 Columbia, S.C.(COLUMN)71(COLUMN) 98 Columbus(COLUMN)58(COLUMN) 87 Dal.-Ft. Worth(COLUMN)75(COLUMN) 98 Dayton(COLUMN)59(COLUMN) 91 Denver(COLUMN)55(COLUMN) 78 Des Moines(COLUMN)38(COLUMN) 36 Detroit(COLUMN)40(COLUMN) 37 Duluth(COLUMN)40(COLUMN) 38 El Paso(COLUMN)65(COLUMN)100 Fairbanks(COLUMN)41(COLUMN) 37 Fargo(COLUMN)40(COLUMN) 37 Flagstaff(COLUMN)60(COLUMN) 88 Great Falls(COLUMN)43(COLUMN) 35 Hartford(COLUMN)39(COLUMN) 34 Helena(COLUMN)42(COLUMN) 36 Honolulu(COLUMN)76(COLUMN) 87 Houston(COLUMN)79(COLUMN) 94 Indianapolis(COLUMN)61(COLUMN) 89 Jackson, Miss.(COLUMN)74(COLUMN) 98 Jacksonville(COLUMN)74(COLUMN) 98 Juneau(COLUMN)42(COLUMN) 39 Kansas City(COLUMN)70(COLUMN) 83 Las Vegas(COLUMN)32(COLUMN)114 Little Rock(COLUMN)74(COLUMN) 93 Los Angeles(COLUMN)64(COLUMN) 84 Louisville(COLUMN)66(COLUMN) 93 Memphis(COLUMN)79(COLUMN) 93 Miami Beach(COLUMN)82(COLUMN) 89 Midland Odessa(COLUMN)70(COLUMN) 99 Milwaukee(COLUMN)39(COLUMN) 36 Mpls.-St. Paul(COLUMN)39(COLUMN) 37 Nashville(COLUMN)74(COLUMN) 93 New Orleans(COLUMN)78(COLUMN) 94 New York(COLUMN)70(COLUMN) 86 Norfolk(COLUMN)75(COLUMN) 92 North Platte(COLUMN)41(COLUMN) 36 Oklahoma City(COLUMN)76(COLUMN) 92 Omaha(COLUMN)64(COLUMN) 77 Orlando(COLUMN)73(COLUMN) 94 Philadelphia(COLUMN)63(COLUMN) 84 Phoenix(COLUMN)84(COLUMN)111 Pittsburgh(COLUMN)40(COLUMN) 36 Portland, Me.(COLUMN)40(COLUMN) 36 Portland, Or.(COLUMN)40(COLUMN) 34 Providence(COLUMN)39(COLUMN) 35 Raleigh(COLUMN)65(COLUMN) 93 Rapid City(COLUMN)42(COLUMN) 36 Reno(COLUMN)59(COLUMN) 91 Richmond(COLUMN)60(COLUMN) 94 St. Louis(COLUMN)74(COLUMN) 91 St. Pbg.-T'mpa(COLUMN)75(COLUMN) 91 Salt Lake City(COLUMN)40(COLUMN) 34 San Antonio(COLUMN)77(COLUMN) 91 San Diego(COLUMN)64(COLUMN) 76 San Francisco(COLUMN)54(COLUMN) 63 San Juan(COLUMN)78(COLUMN) 87 St. Ste. Marie(COLUMN)42(COLUMN) 39 Seattle(COLUMN)40(COLUMN) 35 Shreveport(COLUMN)73(COLUMN) 92 Sioux Falls(COLUMN)40(COLUMN) 36 Spokane(COLUMN)41(COLUMN) 35 Syracuse(COLUMN)40(COLUMN) 35 Topeka(COLUMN)72(COLUMN) 82 Tucson(COLUMN)81(COLUMN)105 Tulsa(COLUMN)77(COLUMN) 95 Washington(COLUMN)67(COLUMN) 91 Wichita(COLUMN)69(COLUMN) 84(END TABLE) Temperatures Abroad Yesterday(TABLE) City(COLUMN)Weather(COLUMN)Time(COLUMN)Temp. Aberdeen(COLUMN)pt. cldy(COLUMN)1 p.m.(COLUMN)61 Amsterdam(COLUMN)pt. cldy(COLUMN)1 p.m.(COLUMN)68 Ankara(COLUMN) clear(COLUMN)3 p.m.(COLUMN)75 Athens(COLUMN) clear(COLUMN)2 p.m.(COLUMN)82 Berlin(COLUMN) clear(COLUMN)1 p.m.(COLUMN)66 Birmingham(COLUMN) cloudy(COLUMN)1 p.m.(COLUMN)61 Brussels(COLUMN) cloudy(COLUMN)1 p.m.(COLUMN)61 Cairo(COLUMN) clear(COLUMN)2 p.m.(COLUMN)90 Casablanca(COLUMN) clear(COLUMN) noon(COLUMN)70 Copenhagen(COLUMN)pt. cldy(COLUMN)1 p.m.(COLUMN)64 Dublin(COLUMN) rain(COLUMN)1 p.m.(COLUMN)63 Geneva(COLUMN) rain(COLUMN)1 p.m.(COLUMN)63 Hong Kong(COLUMN)pt. cldy(COLUMN)8 p.m.(COLUMN)82 Lisbon(COLUMN) clear(COLUMN) noon(COLUMN)82 London(COLUMN)pt. cldy(COLUMN)1 p.m.(COLUMN)66 Madrid(COLUMN) clear(COLUMN)1 p.m.(COLUMN)73 Malta(COLUMN) clear(COLUMN)1 p.m.(COLUMN)79 Moscow(COLUMN) cloudy(COLUMN)3 p.m.(COLUMN)73 New Delhi(COLUMN)pt. cldy(COLUMN)5 p.m.(COLUMN)95 Nice(COLUMN) clear(COLUMN)1 p.m.(COLUMN)72 Oslo(COLUMN) cloudy(COLUMN)1 p.m.(COLUMN)63 Paris(COLUMN) cloudy(COLUMN)1 p.m.(COLUMN)63 Peking(COLUMN)pt. cldy(COLUMN)8 p.m.(COLUMN)79 Rome(COLUMN) clear(COLUMN)1 p.m.(COLUMN)77 Saigon(COLUMN)pt. cldy(COLUMN)8 p.m.(COLUMN)84 Sofia(COLUMN) clear(COLUMN)2 p.m.(COLUMN)77 Stockholm(COLUMN)pt. cldy(COLUMN)1 p.m.(COLUMN)63 Tel Aviv(COLUMN) clear(COLUMN)2 p.m.(COLUMN)86 Tokyo(COLUMN) cloudy(COLUMN)9 p.m.(COLUMN)73 Tunis(COLUMN)pt. cldy(COLUMN)1 p.m.(COLUMN)86 Vienna(COLUMN) cloudy(COLUMN)1 p.m.(COLUMN)66 Warsaw(COLUMN) cloudy(COLUMN)1 p.m.(COLUMN)72(END TABLE) Temperatures (Western Hemisphere)(TABLE) City(COLUMN)Weather(COLUMN)H.(COLUMN)L. Acapulco(COLUMN)pt. sunny(COLUMN)95(COLUMN)81 Barbados(COLUMN) sunny(COLUMN)84(COLUMN)77 Bermuda(COLUMN) sunny(COLUMN)84(COLUMN)77 Calgary(COLUMN) clear(COLUMN)66(COLUMN)41 Culiacan(COLUMN) clear(COLUMN)95(COLUMN)77 Edmonton(COLUMN) clear(COLUMN)64(COLUMN)37 Havana(COLUMN) sunny(COLUMN)90(COLUMN)73 Kingston(COLUMN) sunny(COLUMN)91(COLUMN)77 Montego Bay(COLUMN) sunny(COLUMN)90(COLUMN)73 Mexico City(COLUMN) pt. cldy(COLUMN)79(COLUMN)59 Monterry(COLUMN) sunny(COLUMN)93(COLUMN)73 Montreal(COLUMN) clear(COLUMN)79(COLUMN)57 Nassau(COLUMN) sunny(COLUMN)91(COLUMN)77 Ottawa(COLUMN) clear(COLUMN)77(COLUMN)57 Regina(COLUMN) pt. cldy(COLUMN)68(COLUMN)50 St. Kitts(COLUMN) pt. cldy(COLUMN)89(COLUMN)75 Toronto(COLUMN) clear(COLUMN)72(COLUMN)50 Vancouver(COLUMN) clear(COLUMN)66(COLUMN)50 Veracruz(COLUMN)pt. sunny(COLUMN)90(COLUMN)77 Winnipeg(COLUMN) pt. cldy(COLUMN)72(COLUMN)52(END TABLE)