Washington: Today - Partly cloudy and not quite so hot with a chance of thunderstorms, high in the 90s, low near 70.The chance of rain is 40 percent through tonight. Winds will be from the southwest at 10 m.p.h. shifting to the northwest by evening. Tuesday - variable cloudiness, high in the upper 80s.

Maryland: Today - Partly cloudy and not quite so warm with a chance of thunderstorms. Highs from the 80s to mid 90s, lows from the 60s to low 70s. Tuesday - Variable cloudiness, highs from the 70s to mid 80s.

Virginia: Today - Partly cloudy and not quite so hot. Highs in the 80s to upper 90s, lows in the 60s to mid 70s. Tuesday - Variable cloudiness and cooler, highs from the 70s to near 90.

Extended Area Forecast for Wednesday through Friday - Partly cloudy, warm and humid with a chance of afternoon and evening thundershowers. Highs will be in the upper 80s to mid 90s, lows in the mid 60s to mid 70s. Normal Washington temperatures are a high of 88 and a low of 69.

Lower Potomac and Chesapeake Bay - chance of a thunderstorm. Visibility will be 1 to 3 miles in haze diminishing to less than 1 mile in fog and thunderstorms. Winds will be northwesterly at 6 to 12 knots. Waves will average 1 to 2 feet.

Atlantic Coast Beaches from New Jersey to Maryland: Today - Chance of thunderstorms, high in the mid 80s. Tuesday - Variable cloudiness and cooler, high near 80s. Water temperatures will range from the 60s to low 70s.

Atlantic Ocean Beaches from Virginia to North Carolina: Today - hot and humid with a chance of thunderstorms, high near 90. Tuesday - Partly cloudy and not quite so hot, high in the low to mid 80s. Water temperatures will be in the mid to upper 70s.

West Virginia: Today and Tuesday - Variable cloudiness and cooler, high in the 80s, lows in the 60s.

The Council of Governments' Air Quality Index for yesterday showed the high reading in the Washington area during the 3 p.m. period was 55 for the pollutant, photochemical oxidants. Index values between 50 and 99 indicate unhealthy air quality. When the index exceeds 100 the air is considered very unhealthy and individuals with lung, heart and eye ailments are urged to restrict their activity. The air stagnation remains in effect through noon today.

The National Weather Service forecasts the Potomac River Stage at Little Falls should stay between 3.2 and 3.3 feet today.

The National Weather Forecast for today - Showers and thunderstorms will be numerous over the Tennessee and lower Ohio Valleys. Other thundershowers activity will be scattered over the southern tier of states from Arizona to Florida and the southern Atlantic Coast states. Sunshine will cover the rest of the nation. Temperatures will be quite warm, mostly in the 90s over a large part of the country. Slightly cooler air will be found from northern New England through the Ohio Valley, the Great Lakes area and the middle and upper Mississippi Valley. It will be considerably cooler along the northern Pacific Coast.

Almanac Data for today: The sun rises 6:02 a.m., sets 8:27 p.m.; moon rises 11:28 p.m., set 11:14 a.m. Tides: high 12:19 p.m. low 6:43 a.m. and 7:07 p.m. High and low tides at the following locations may be obtained by subtracting the hours indicated from the hours above: Annapolis (3 1/4), Bloody Point Lighthouse (4 1/2), Deale Md. (4 1/2), Colonial Beach (5 1/4), Norfolk (1), Virginia Beach (3/4), Solomons Island (6 1/4), Point Lookout (7). Local Temps, Humidity(TABLE) Time(COLUMN)T.(COLUMN)H. 12 midnight(COLUMN) 86(COLUMN)83 1 a.m.(COLUMN) 85(COLUMN)85 2 a.m.(COLUMN) 85(COLUMN)85 3 a.m.(COLUMN) 83(COLUMN)88 4 a.m.(COLUMN) 82(COLUMN)88 5 a.m.(COLUMN) 82(COLUMN)88 6 a.m.(COLUMN) 82(COLUMN)88 5 2 a.m.(COLUMN) 85(COLUMN)85 3 a.m.(COLUMN) 82(COLUMN)88 6 a.m.(COLUMN) 82(COLUMN)88 7 a.m.(COLUMN) 81(COLUMN)91 8 a.m.(COLUMN) 84(COLUMN)85 9 a.m.(COLUMN) 86(COLUMN)83 10 a.m.(COLUMN)88(COLUMN)78 11 a.m.(COLUMN) 93(COLUMN)58 12 noon(COLUMN) 95(COLUMN)51 1 p.m.(COLUMN) 97(COLUMN)47 2 p.m.(COLUMN) 97(COLUMN)47 3 p.m.(COLUMN)100(COLUMN)42 4 p.m.(COLUMN)100(COLUMN)40 5 p.m.(COLUMN) 98(COLUMN)43 6 p.m.(COLUMN) 97(COLUMN)47 7 p.m.(COLUMN) 95(COLUMN)51(END TABLE) Temperature ending 8 a.m. (EDT) yesterday:(TABLE) City(COLUMN)H.(COLUMN)L. Albany(COLUMN)90(COLUMN)71 Albuquerque(COLUMN)90(COLUMN)66 Amarillo(COLUMN)78(COLUMN)66 Anchorage(COLUMN)61(COLUMN)51 Asheville(COLUMN)90(COLUMN)66 Atlanta(COLUMN)94(COLUMN)70 Atlantic City(COLUMN)91(COLUMN)76 Austin(COLUMN)98(COLUMN)76 Baltimore(COLUMN)98(COLUMN)79 Billings(COLUMN)80(COLUMN)55 Birmingham(COLUMN)90(COLUMN)70 Bismarck(COLUMN)76(COLUMN)56 Boise(COLUMN)94(COLUMN)64 Boston(COLUMN)94(COLUMN)73 Brownsville(COLUMN)97(COLUMN)75 Buffalo(COLUMN)88(COLUMN)79 Burlington, Vt.(COLUMN)84(COLUMN)71 Casper(COLUMN)76(COLUMN)48 Charleston, S.C.(COLUMN)92(COLUMN)79 Charleston, W.Va.(COLUMN)92(COLUMN)72 Charlotte(COLUMN)93(COLUMN)72 Cheyenne(COLUMN)70(COLUMN)47 Chicago(COLUMN)94(COLUMN)64 Cincinnati(COLUMN)94(COLUMN)72 Cleveland(COLUMN)96(COLUMN)76 Columbia, S.C.(COLUMN)90(COLUMN)70 Columbus(COLUMN)96(COLUMN)74 Dal.-Ft. Worth(COLUMN)98(COLUMN)76 Dayton(COLUMN)93(COLUMN)72 Denver(COLUMN)77(COLUMN)50 Des Moines(COLUMN)84(COLUMN)50 Detroit(COLUMN)95(COLUMN)72 Duluth(COLUMN)66(COLUMN)48 El Paso(COLUMN)89(COLUMN)68 Evansville(COLUMN)96(COLUMN)71 Fairbanks(COLUMN)64(COLUMN)49 Fargo(COLUMN)72(COLUMN)56 Flagstaff(COLUMN)89(COLUMN)55 Great Falls(COLUMN)84(COLUMN)52 Hartford(COLUMN)93(COLUMN)73 Helena(COLUMN)83(COLUMN)50 Honolulu(COLUMN)86(COLUMN)73 Houston(COLUMN)85(COLUMN)74 Indianapolis(COLUMN)93(COLUMN)75 Jackson(COLUMN)88(COLUMN)71 Jacksonville(COLUMN)89(COLUMN)73 Juneau(COLUMN)60(COLUMN)53 Kansas City(COLUMN)82(COLUMN)64 Las Vegas(COLUMN)111(COLUMN)80 Little Rock(COLUMN)90(COLUMN)71 Los Angeles(COLUMN)87(COLUMN)60 Louisville(COLUMN)94(COLUMN)76 Memphis(COLUMN)93(COLUMN)75 Miami Beach(COLUMN)87(COLUMN)76 Midland(COLUMN)98(COLUMN)69 Milwaukee(COLUMN)88(COLUMN)61 Mpls.-St. Paul(COLUMN)69(COLUMN)50 Nashville(COLUMN)94(COLUMN)74 New Orleans(COLUMN)88(COLUMN)74 New York(COLUMN)92(COLUMN)81 Norfolk(COLUMN)94(COLUMN)77 North Platte(COLUMN)72(COLUMN)49 Oklahoma City(COLUMN)94(COLUMN)72 Omaha(COLUMN)71(COLUMN)57 Orlando(COLUMN)92(COLUMN)74 Philadelphia(COLUMN)98(COLUMN)80 Phoenix(COLUMN)105(COLUMN)77 Pittsburgh(COLUMN)95(COLUMN)76 Portland, Me.(COLUMN)89(COLUMN)68 Portland, Ore.(COLUMN)98(COLUMN)65 Providence(COLUMN)92(COLUMN)78 Raleigh(COLUMN)95(COLUMN)75 Rapid City(COLUMN)73(COLUMN)53 Reno(COLUMN)99(COLUMN)55 Richmond(COLUMN)98(COLUMN)74 St. Louis(COLUMN)91(COLUMN)74 St. Prbg.-Tampa(COLUMN)90(COLUMN)76 Salt Lake City(COLUMN)91(COLUMN)59 San Antonio(COLUMN)98(COLUMN)78 San Diego(COLUMN)77(COLUMN)68 San Francisco(COLUMN)61(COLUMN)53 San Jaun(COLUMN)89(COLUMN)77 St. Ste. Marie(COLUMN)75(COLUMN)59 Seattle(COLUMN)95(COLUMN)63 Shreveport(COLUMN)91(COLUMN)69 Sioux Falls(COLUMN)71(COLUMN)49 Spokane(COLUMN)90(COLUMN)59 Syracuse(COLUMN)90(COLUMN)74 Topeka(COLUMN)83(COLUMN)61 Tucson(COLUMN)86(COLUMN)77 Tulsa(COLUMN)98(COLUMN)73 Washington(COLUMN)98(COLUMN)81 Wichita(COLUMN)85(COLUMN)64(END TABLE) Temperatures ending 8 a.m. (EDT) yesterday:(TABLE) City(COLUMN)Weather(COLUMN)Time(COLUMN)Temp. Aberdeen(COLUMN)pt. cldy(COLUMN)1 p.m.(COLUMN)66 Amsterdam(COLUMN)pt. cldy(COLUMN)1 p.m.(COLUMN)72 Ankara(COLUMN)pt. cldy(COLUMN)3 p.m.(COLUMN)72 Athens(COLUMN)clear(COLUMN)2 p.m.(COLUMN)79 Berlin(COLUMN)clear(COLUMN)1 p.m.(COLUMN)70 Birmingham(COLUMN)cldy(COLUMN)1 p.m.(COLUMN)61 Bonn(COLUMN)cloudy(COLUMN)1 p.m.(COLUMN)68 Brussels(COLUMN)pt. cldy(COLUMN)1 p.m.(COLUMN)72 Cairo(COLUMN)clear(COLUMN)2 p.m.(COLUMN)88 Casablanca(COLUMN)clear(COLUMN)noon(COLUMN)82 Copenhagen(COLUMN)pt. cldy(COLUMN)1 p.m.(COLUMN)66 Dublin(COLUMN)cloudy(COLUMN)1 p.m.(COLUMN)66 Geneva(COLUMN)clear(COLUMN)1 p.m.(COLUMN)70 Hong Kong(COLUMN)cloudy(COLUMN)8 p.m.(COLUMN)82 Jerusalem(COLUMN)clear(COLUMN)2 p.m.(COLUMN)81 Lisbon(COLUMN)pt. cldy(COLUMN)noon(COLUMN)90 London(COLUMN)rain(COLUMN)1 p.m.(COLUMN)61 Madrid(COLUMN)cloudy(COLUMN)1 p.m.(COLUMN)82 Malta(COLUMN)clear(COLUMN)1 p.m.(COLUMN)81 Manila(COLUMN)pt. cldy(COLUMN)8 p.m.(COLUMN)79 Moscow(COLUMN)cloudy(COLUMN)3 p.m.(COLUMN)68 New Delhi(COLUMN)pt. cldy(COLUMN)5 p.m.(COLUMN)90 Nice(COLUMN)clear(COLUMN)1 p.m.(COLUMN)75 Oslo(COLUMN)pt. cldy(COLUMN)1 p.m.(COLUMN)66 Paris(COLUMN)clear(COLUMN)1 p.m.(COLUMN)75 Peking(COLUMN)rain(COLUMN)8 p.m.(COLUMN)77 Rome(COLUMN)clear(COLUMN)1 p.m.(COLUMN)81 Saigon(COLUMN)rain(COLUMN)8 p.m.(COLUMN)77 Sofia(COLUMN)clear(COLUMN)2 p.m.(COLUMN)64 Stockholm(COLUMN)clear(COLUMN)1 p.m.(COLUMN)68 Sydney(COLUMN)clear(COLUMN)10 p.m.(COLUMN)50 Tokyo(COLUMN)cloudy(COLUMN)9 p.m.(COLUMN)82 Tunis(COLUMN)clear(COLUMN)1 p.m.(COLUMN)81 Vienna(COLUMN)pt. cldy(COLUMN)1 p.m.(COLUMN)68 Warsaw(COLUMN)pt. cldy(COLUMN)1 p.m.(COLUMN)63(END TABLE) Temperatures (Western Hemisphere)(TABLE) City(COLUMN)Weather(COLUMN)High(COLUMN)Low Acapulco(COLUMN)pt. cldy(COLUMN)90(COLUMN)75 Barbados(COLUMN)fair(COLUMN)86(COLUMN)75 Bermuda(COLUMN)fair(COLUMN)87(COLUMN)80 Bogota(COLUMN)pt. cldy(COLUMN)68(COLUMN)44 Calgary(COLUMN)cloudy(COLUMN)79(COLUMN)57 Culiacan(COLUMN)pt. cldy(COLUMN)101(COLUMN)77 Edmonton(COLUMN)pt. cldy(COLUMN)79(COLUMN)50 Havana(COLUMN)cloudy(COLUMN)88(COLUMN)73 Kingston(COLUMN)fair(COLUMN)90(COLUMN)80 Montego Bay(COLUMN)pt. cldy(COLUMN)90(COLUMN)73 Culiacan(COLUMN)pt. cldy(COLUMN)101(COLUMN)77 Mexico City(COLUMN)pt. cldy(COLUMN)76(COLUMN)57 Monterrey(COLUMN)pt. cldy(COLUMN)101(COLUMN)77 Montreal(COLUMN)clear(COLUMN)83(COLUMN)70 Nassau(COLUMN)pt. cldy(COLUMN)88(COLUMN)79 Ottawa(COLUMN)cloudy(COLUMN)82(COLUMN)68 Regina(COLUMN)clear(COLUMN)75(COLUMN)50 St. Kitts(COLUMN)fair(COLUMN)88(COLUMN)76 St. Thomas(COLUMN)fair(COLUMN)89(COLUMN)80 Vancouver(COLUMN)clear(COLUMN)82(COLUMN)66 Veracruz(COLUMN)fair(COLUMN)86(COLUMN)73 Winnipeg(COLUMN)fog(COLUMN)73(COLUMN)52(END TABLE)