Washington: Today - Partly cloudy and warm with a chance of afternoon and evening thundershowers, high in the 80s, low in the 60s. The chance of rain is 30 percent through tonight. Wednesday - Partly cloudy and continued warm with chance of afternoon and evening thundershowers, high in the 80s. Winds both days will be light and various.

Maryland and Virginia: Partly cloudy and warm through Wednesday with a chance of afternoon, and evening thundershowers both days. Highs both days will be in the 80s, lows in the 60s.

Extended Area Forecast for Thursday through Saturday - Partly cloudy and warm. Highs will be in the 80s, lows in the 60s. Normal Washington temperatures for the period are a high of 82 and a low of 61.

Lower Potomac and Chesapeake Bay - Partly cloudy with visibility improving to 3 to 5 miles by afternoon. Winds will be from the southwest at 10 knots or less. Waves will average hear 1 foot.

Atlantic Ocean Beaches from New Jersey to North Caroline - Early morning fog followed by partly cloudy skies, high in the 70s. Wednesday - Partly cloudy with the chances of showers, high again in the 70s. Water temperature range from the upper 50s in New Jersey to the mid 60s in North Caroline.

West Virginia: Today - Variable cloudiness with a chance of showers or thundershowers, high from the mid 70s to mid 80s, low from the mid 50s to mid 60s. Wednesday - Partly cloudy, high from the mid 70s to mid 80s.

The national weather forecast for today - Showers and thunderstorms are expected from the Great Lakes region through the Ohio Valley. Scattered shower activity will reach into New England, and also over the central and northern Rockies. Skies will be sunny over the southern Rockies,the Plateau region and the Far West. Temperatures will be mild to warm over most of the country except for cool readings from the northern Rockies through the upper Mississippi Valley.

Almanac Data for today: The sun rises 5:46 a.m., sets 8:26 p.m., moon rises 2:17 a.m., sets 2:33 p.m. Tides: high 3:42 a.m. and 4:04 p.m., low 10:28 a.m. and 10:49 p.m. High and low tides at the following locations may be obtained by subtracting the hours indicated from the hours above: Annapalois (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 Lockout (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 41 for the pollutant, photochemical oxidents, Index values between 25 and 49 indicate fair 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 aie quality will remain about the same.

The National Weather Service forecasts the Potamac River stage at Little Falls should remain near 4-4 feet today. Local Temps., Humidity(TABLE) Time(COLUMN)T.(COLUMN)H. 12 mid.(COLUMN)69(COLUMN)84 1 a.m.(COLUMN)68(COLUMN)87 2 a.m.(COLUMN)67(COLUMN)90 3 a.m.(COLUMN)68(COLUMN)87 4 a.m.(COLUMN)67(COLUMN)90 5 a.m.(COLUMN)67(COLUMN)90 6a.m.(COLUMN)67(COLUMN)90 7 a.m.(COLUMN)67(COLUMN)90 8 a.m.(COLUMN)69(COLUMN)84 9 a. m.(COLUMN)70(COLUMN)82 10 a.m.(COLUMN)71(COLUMN)79 11 a.m.(COLUMN)72(COLUMN)76 12 noon(COLUMN)75(COLUMN)71 1 p.m.(COLUMN)79(COLUMN)65 2 p.m.(COLUMN)79(COLUMN)65 3 p.m.(COLUMN)80(COLUMN)63 4 p.m.(COLUMN)80(COLUMN)63 5 p.m.(COLUMN)80(COLUMN)63 6 p.m.(COLUMN)79(COLUMN)69 7 p.m.(COLUMN)78(COLUMN)67(END TABLE) Temperatures ending 8 a.m. (EDT) yesterday:(TABLE) City(COLUMN)H.(COLUMN)L. Albany(COLUMN)87(COLUMN)62 Albuquerque(COLUMN)82(COLUMN)55 Amarillo(COLUMN)73(COLUMN)55 Anchorage(COLUMN)61(COLUMN)46 Asheville(COLUMN)77(COLUMN)62 Atlanta(COLUMN)82(COLUMN)64 Atlantic City(COLUMN)60(COLUMN)54 Austin(COLUMN)89(COLUMN)68 Baltimore(COLUMN)78(COLUMN)64 Billings(COLUMN)82(COLUMN)49 Birmingham(COLUMN)85(COLUMN)66 Bismarck(COLUMN)75(COLUMN)49 Boise(COLUMN)76(COLUMN)47 Boston(COLUMN)77(COLUMN)65 Brownsville(COLUMN)94(COLUMN)73 Buffalo(COLUMN)84(COLUMN)66 Burlington, Vt.(COLUMN)92(COLUMN)64 Casper(COLUMN)68(COLUMN)40 Charleston, S.C.(COLUMN)80(COLUMN)70 Charleston, W.V.(COLUMN)84(COLUMN)63 Charlotte(COLUMN)78(COLUMN)64 Cheyanne(COLUMN)58(COLUMN)40 Chicago(COLUMN)91(COLUMN)68 Cincinnati(COLUMN)88(COLUMN)65 Cleveland(COLUMN)88(COLUMN)62 Columbia, S.C.(COLUMN)84(COLUMN)65 Columbus(COLUMN)85(COLUMN)65 Dal.-Ft. Worth(COLUMN)83(COLUMN)64 Dayton(COLUMN)88(COLUMN)64 Denver(COLUMN)68(COLUMN)43 Des Moines(COLUMN)79(COLUMN)65 Detroit(COLUMN)88(COLUMN)59 Duluth(COLUMN)64(COLUMN)49 El Paso(COLUMN)91(COLUMN)56 Fairbanks(COLUMN)62(COLUMN)45 Fargo(COLUMN)71(COLUMN)60 Flagstaff(COLUMN)74(COLUMN)31 Great Falls(COLUMN)71(COLUMN)39 Hartford(COLUMN)87(COLUMN)63 Helena(COLUMN)74(COLUMN)52 Honolulu(COLUMN)86(COLUMN)71 Houston(COLUMN)88(COLUMN)75 Indianapolis(COLUMN)90(COLUMN)69 Jackson(COLUMN)89(COLUMN)69 Jacksonville(COLUMN)86(COLUMN)65 Juneau(COLUMN)56(COLUMN)45 Kansas City(COLUMN)80(COLUMN)60 Las Vegas(COLUMN)96(COLUMN)64 Little Rock(COLUMN)84(COLUMN)69 Los Angeles(COLUMN)91(COLUMN)70 Louisville(COLUMN)89(COLUMN)68 Memphis(COLUMN)92(COLUMN)70 Miami Beach(COLUMN)79(COLUMN)72 Midland(COLUMN)87(COLUMN)59 Milwaukee(COLUMN)84(COLUMN)61 Mpls,-St. Paul(COLUMN)78(COLUMN)63 Nashville(COLUMN)91(COLUMN)67 New Orleans(COLUMN)89(COLUMN)66 New York(COLUMN)81(COLUMN)62 Norfolk(COLUMN)69(COLUMN)62 North Platte(COLUMN)67(COLUMN)52 Oklahoma City(COLUMN)75(COLUMN)60 Omaha(COLUMN)80(COLUMN)57 Orlando(COLUMN)91(COLUMN)70 Philadelphia(COLUMN)78(COLUMN)62 Phoenix(COLUMN)100(COLUMN)72 Pittsburgh(COLUMN)84(COLUMN)63 Portland, Me.(COLUMN)80(COLUMN)55 Portland, Ore.(COLUMN)62(COLUMN)41 Providence(COLUMN)75(COLUMN)62 Raleigh(COLUMN)81(COLUMN)56 Rapid City(COLUMN)64(COLUMN)47 Reno(COLUMN)84(COLUMN)43 Richmond(COLUMN)73(COLUMN)65 St. Louis(COLUMN)88(COLUMN)66 St. Prbg.-Tampa(COLUMN)88(COLUMN)71 Salt Lake City(COLUMN)75(COLUMN)50 San Antonio(COLUMN)88(COLUMN)69 San Diego(COLUMN)83(COLUMN)67 San Francisco(COLUMN)67(COLUMN)55 San Juan(COLUMN)89(COLUMN)76 St. Ste. Marie(COLUMN)88(COLUMN)57 Seattle(COLUMN)62(COLUMN)46 Shreveport(COLUMN)90(COLUMN)70 Sloux Falls(COLUMN)73(COLUMN)56 Spokane(COLUMN)61(COLUMN)39 Syracuse(COLUMN)88(COLUMN)60 Topeka(COLUMN)86(COLUMN)58 Tucson(COLUMN)94(COLUMN)61%LTulsa 83(COLUMN)66 Washington(COLUMN)80(COLUMN)67 Wichita(COLUMN)82(COLUMN)57(END TABLE) Temperatures (Western Hemisphere)(TABLE) City(COLUMN)Weather(COLUMN)High(COLUMN)Low Acapulco(COLUMN)cloudy(COLUMN)92(COLUMN)78 Barbados(COLUMN)fair(COLUMN)87(COLUMN)76 Bermuda(COLUMN)showers(COLUMN)78(COLUMN)74 Caigary(COLUMN)pt. Cldy.(COLUMN)63(COLUMN)46 Cullecan(COLUMN)fair(COLUMN)101(COLUMN)63 Edmonton(COLUMN)cloudy(COLUMN)63(COLUMN)46 Havana(COLUMN)cloudy(COLUMN)85(COLUMN)77 Kingston(COLUMN)rain(COLUMN)88(COLUMN)76 Montego Bay(COLUMN)showers(COLUMN)85(COLUMN)76 Mexico City(COLUMN)haze(COLUMN)82(COLUMN)59 Monterray(COLUMN)pt. cldy.(COLUMN)92(COLUMN)74 Nassau(COLUMN)cloudy(COLUMN)82(COLUMN)71 Ottawa(COLUMN)clear(COLUMN)91(COLUMN)61 Regina(COLUMN)pt. cldy.(COLUMN)77(COLUMN)45 St. Thomas(COLUMN)fair(COLUMN)88(COLUMN)80 Toronto(COLUMN)clear(COLUMN)82(COLUMN)55 Vancouver(COLUMN)cloudy(COLUMN)61(COLUMN)48 Veracruz(COLUMN)pt. cldy.(COLUMN)90(COLUMN)76 Winnipeg(COLUMN)cloudy(COLUMN)81(COLUMN)54(END TABLE)