Washington: Today - Cloudy with a chance of showers or thunderstorms, high in the 80s, low near 70. The chance of rain is 40 percent through tonight. Winds will be from the south at 10 mph. Tuesday - Sunny, hot and humid, high in the 90s.

Maryland and Virginia: Today - Cloudy, with a chance of showers or thunderstorms, high in the 80s, low in the 60s to near 70. Tuesday - Sunny, hot and humid, high in the 90s.

Extended Area Forecast for Wednesday through Friday - Hot and humid through the period with isolated thundershowers.Highs will average from the mid 80s mid 90s lows from the 60s to mid 70s. Normal Washington temperatures from the period are a high of 87 and a low of 68.

Lower Potomac and Chesapeake Bay - Cloudy with a chance of thunderstorms, followed by clearing skies. Winds will be from the south at 10 knots. Visibility will be 5 miles or more diminishing to loss than 1 mile in rain. Waves will average near 1 foot.

Atlantic Ocean Beaches from New Jersey to North Carolina: Today - Cloudy with a chance of showers of thunderstorms, high in the 80s. Tuesday - Sunny, hot and humid, high in the 80s. Water temperatures will range from the low to mid 60s in the north to the low 70s in the south.

The National Weather Forecast for today - Scattered thunderstorms will continue from the northern Plains to the upper Great Lakes region. Widely scattered thundershowers will develop from New England down the Atlantic Coast states to Florida. Most of the West and South will be sunny. The Pacific Northwest and most of the northern Plains will continue cool with temperatures mostly in the 60s and 70s. The hot weather will continue across the Southwest with many reading in the 100s, and will stretch well into the middle Mississippi Valley. New England will be warm.

Almanac Data for today. The sun rises 11:53 p.m. sets 11:24 a.m. Tides: high 12:18 a.m. and 12:36 p.m., low 7:03 a.m. and 7:27 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).

The Council of Governments' Air Quality Index for yesterday showed the high reading in the Washington area during the 1 p.m. period was 120 for the pollutant, photochemical oxidants. Index values between 100 indicates very 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 forecast for today indicates that the air quality will improve.

The National Weather Services forecasts the Potomac River Stage at Little Falls should decrease to near 3.3 feet today.

Washington data for yesterday: Highest temperature since midnight yesterday, 88 degrees at 2:30 p.m. Lowest temperature since midnight, 67 degrees at 6:20 a.m. Excess of temperature since June 1, 43 degrees. Deficiency of temperature since Jan. 1, 177 degrees. Record high temperature for today, 101 degrees in 1952. Record low temperature for today, 57 degrees in 1873. Relative humidity: maximum, 81 percent at 5 a.m.; minimum 41 percent at 4 p.m. 24 hour precipitation, none. Deficiency of precipitation since June 1, 1.58 inches. Excess of precipitation since Jan. 1, 2.00 inches.Highest observed wind since 8 a.m. 13 miles per hour from the south southeast at 1:53 p.m. Peak gust since 8 a.m., 15 miles per hour from the south at 1:32 p.m. Local Temps., Humidity(TABLE) Time(COLUMN)T.(COLUMN)H. 12 mid.(COLUMN)72(COLUMN)69 1 a.m.(COLUMN)73(COLUMN)69 2 a.m.(COLUMN)71(COLUMN)76 3 a.m.(COLUMN)70(COLUMN)79 4 a.m.(COLUMN)69(COLUMN)79 5 a.m.(COLUMN)68(COLUMN)81 6 a.m.(COLUMN)68(COLUMN)81 7 a.m.(COLUMN)69(COLUMN)79 8 a.m.(COLUMN)72(COLUMN)76 9 a.m.(COLUMN)75(COLUMN)67 10 a.m.(COLUMN)79(COLUMN)60 11 a.m.(COLUMN)82(COLUMN)51 12 noon(COLUMN)83(COLUMN)51 1 p.m.(COLUMN)85(COLUMN)43 2 p.m.(COLUMN)85(COLUMN)45 3 p.m.(COLUMN)87(COLUMN)42 4 p.m.(COLUMN)88(COLUMN)41 5 p.m.(COLUMN)85(COLUMN)45 6 p.m.(COLUMN)86(COLUMN)45 7 p.m.(COLUMN)83(COLUMN)57(END TABLE) Temperatures ending 8 p.m. (EDT) yesterday(TABLE) City(COLUMN)H.(COLUMN)L. Albany(COLUMN) 79(COLUMN)50 Albuquerque(COLUMN)100(COLUMN)67 Amarillo(COLUMN)100(COLUMN)73 Anchorage(COLUMN) 57(COLUMN)52 Asheville(COLUMN) 86(COLUMN)56 Atlanta(COLUMN) 88(COLUMN)70 Atlantic City(COLUMN) 70(COLUMN)61 Austin(COLUMN) 96(COLUMN)78 Baltimore(COLUMN) 84(COLUMN)59 Billings(COLUMN) 83(COLUMN)52 Birmingham(COLUMN) 92(COLUMN)70 Bismarck(COLUMN) 85(COLUMN)62 Boise(COLUMN) 78(COLUMN)46 Boston(COLUMN) 79(COLUMN)58 Brownsville(COLUMN) 97(COLUMN)81 Buffalo(COLUMN) 77(COLUMN)52 Burlington, Vt.(COLUMN) 71(COLUMN)48 Casper(COLUMN) 86(COLUMN)52 Charleston, S.C.(COLUMN) 90(COLUMN)77 Charleston, W.Va.(COLUMN) 83(COLUMN)58 Charlotte(COLUMN) 89(COLUMN)66 Cheyenne(COLUMN) 87(COLUMN)52 Chicago(COLUMN) 87(COLUMN)70 Cincinnati(COLUMN) 83(COLUMN)67 Cleveland(COLUMN) 80(COLUMN)64 Columbia, S.C.(COLUMN) 88(COLUMN)72 Columbus(COLUMN) 82(COLUMN)62 Dal.-Ft. Worth(COLUMN)100(COLUMN)77 Dayton(COLUMN) 85(COLUMN)66 Denver(COLUMN) 95(COLUMN)54 Des Moines(COLUMN) 90(COLUMN)76 Detroit(COLUMN) 83(COLUMN)61 Duluth(COLUMN) 76(COLUMN)55 El Paso(COLUMN)111(COLUMN)73 Fairbanks(COLUMN) 59(COLUMN)46 Fargo(COLUMN) 83(COLUMN)65 Flagstaff(COLUMN) 87(COLUMN)61 Great Falls(COLUMN) 79(COLUMN)50 Hartford(COLUMN) 81(COLUMN)52 Helena(COLUMN) 79(COLUMN)52 Honolulu(COLUMN) 85(COLUMN)73 Houston(COLUMN) 94(COLUMN)78 Indianapolis(COLUMN) 88(COLUMN)74 Jackson(COLUMN) 96(COLUMN)75 Jacksonville(COLUMN) 91(COLUMN)70 Juneau(COLUMN) 60(COLUMN)48 Kansas City(COLUMN) 90(COLUMN)77 Las Vegas(COLUMN)105(COLUMN)72 Little Rock(COLUMN) 94(COLUMN)75 Los Angeles(COLUMN) 87(COLUMN)64 Louisville(COLUMN) 87(COLUMN)70 Memphis(COLUMN) 92(COLUMN)79 Miami Beach(COLUMN) 87(COLUMN)75 Midland(COLUMN) 98(COLUMN)71 Milwaukee(COLUMN) 75(COLUMN)64 Mpls.-St. Paul(COLUMN) 78(COLUMN)73 Nashville(COLUMN) 91(COLUMN)70 New Orleans(COLUMN) 94(COLUMN)78 New York(COLUMN) 77(COLUMN)63 Norfolk(COLUMN) 83(COLUMN)64 North Platte(COLUMN) 92(COLUMN)64 Oklahoma City(COLUMN) 94(COLUMN)77 Omaha(COLUMN) 89(COLUMN)75 Orlando(COLUMN) 95(COLUMN)72 Philadelphia(COLUMN) 80(COLUMN)59 Phoenix(COLUMN)114(COLUMN)84 Pittsburgh(COLUMN) 82(COLUMN)57 Portland, Me.(COLUMN) 73(COLUMN)51 Portland, Or.(COLUMN) 68(COLUMN)56 Providence(COLUMN) 78(COLUMN)58 Raleigh(COLUMN) 88(COLUMN)67 Rapid City(COLUMN) 91(COLUMN)61 Reno(COLUMN) 76(COLUMN)35 Richmond(COLUMN) 85(COLUMN)60 St. Louis(COLUMN) 90(COLUMN)75 St. Prbg.-Tampa(COLUMN) 93(COLUMN)73 Salt Lake City(COLUMN) 95(COLUMN)52 San Antonio(COLUMN) 97(COLUMN)78 San Diego(COLUMN) 83(COLUMN)66 San Francisco(COLUMN) 62(COLUMN)54 San Juan(COLUMN) 90(COLUMN)74 St. Ste. Marie(COLUMN) 79(COLUMN)55 Seattle(COLUMN) 69(COLUMN)56 Shreveport(COLUMN) 97(COLUMN)75 Sioux Falls(COLUMN) 83(COLUMN)66 Spokane(COLUMN) 61(COLUMN)50 Syracuse(COLUMN) 73(COLUMN)51 Topeka(COLUMN) 91(COLUMN)77 Tucson(COLUMN)108(COLUMN)76 Tulsa(COLUMN) 93(COLUMN)78 Washington(COLUMN) 86(COLUMN)67 Wichita(COLUMN) 99(COLUMN)76(END TABLE) Temperatures (Western Hemisphere)(TABLE) City(COLUMN)Weather(COLUMN)Time(COLUMN)T. Amsterdam(COLUMN)rain(COLUMN)1 p.m.(COLUMN)59 Athens(COLUMN)cloudy(COLUMN)1 p.m.(COLUMN)91 Berlin(COLUMN)cloudy(COLUMN)1 p.m.(COLUMN)68 Brussels(COLUMN)cloudy(COLUMN)1 p.m.(COLUMN)60 Cairo(COLUMN)clear(COLUMN)5 p.m.(COLUMN)91 Copenhagen(COLUMN)cloudy(COLUMN)1 p.m.(COLUMN)68 Geneva(COLUMN)cloudy(COLUMN)1 p.m.(COLUMN)59 Hong Kong(COLUMN)clear(COLUMN)8 p.m.(COLUMN)88 Jerusalem(COLUMN)clear(COLUMN)5 p.m.(COLUMN)79 London(COLUMN)clear(COLUMN)1 p.m.(COLUMN)64 Madrid(COLUMN)clear(COLUMN)1 p.m.(COLUMN)73 Manila(COLUMN)cloudy(COLUMN)8 p.m.(COLUMN)89 Moscow(COLUMN)clear(COLUMN)3 p.m.(COLUMN)68 New Delhi(COLUMN)rain(COLUMN)5 p.m.(COLUMN)93 Oslo(COLUMN)cloudy(COLUMN)1 p.m.(COLUMN)61 Paris(COLUMN)cloudy(COLUMN)1 p.m.(COLUMN)61 Rome(COLUMN)clear(COLUMN)2 p.m.(COLUMN)79 Stockholm(COLUMN)cloudy(COLUMN)1 p.m.(COLUMN)72 Tokyo(COLUMN)cloudy(COLUMN)9 p.m.(COLUMN)82 Vienna(COLUMN)rain(COLUMN)1 p.m.(COLUMN)59(END TABLE)