Washington: Today - Variable cloudiness, high 85 to 90, low 62 to today and near zero tonight. Winds will be northwesterly at 10 mph. Monday - Sunny, high in mid 80s.

Maryland and Virginia: Today - Chance of morning showers in the mountains otherwise variable cloudiness. Highs will be mostly in the 80s, and lows in the 60s. Monday - Sunny, high in 80s.

Lower Potomac and Chesapeake Bay: Today - Fair, visibility more than five miles. Winds will be northerly at 12 knots. Waves in unprotected waters will be one foot.

Atlantic Ocean Beaches from New Jersey to North Carolina: Today - Variable cloudiness, highs in the mid to upper 80s. Monday - Sunny, highs around 80. Water temperatures will be in the low 70s in the north and around 80 in the south.

Extended Area Outlook for Tuesday through Thursday: It will be fair through the period except a chance of showers in the mountains on Thursday. Highs will average in the 80s at the beginning of the period and mid 80s to near 90 by Thursday. Lows will average in the 60s through the period. Normal Washington temperatures for the period will be high of 86 and low of 67.

The Nation yesterday:

Showers and thunderstorms over the nation extended from the southern Rockies through the Texas panhandle, Oklahoma and northern Arkansas. Thunderstorm activity was also scattered across the Gulf Coast region and the southern Appalachians. The only other portion of the country which did not have mostly sunny skies was the Pacific northwest, where extensive cloudiness and a few shower's were observed. Temperatures were quite hot, in the 90s, from the southern Plains across the southeastern states. Humidities were running high over the region. By contrast, a large high pressure area centered over Kansas continued to produce pleasant temperatures in the 70s and lower 80s from the central and northern Rockies through the upper Mississippi Valley. Laramie, Wy. had its coldest temperature ever recorded in August this morning when the mercury plumetted to 28 degrees. The previous record was 29 degrees set in 1960 and earlier dates.

The National Weather Forecast for today - showers and thunderstorms will be scattered over New England and the mid Atlantic Coastal region, the Gulf Coast area, and the Pacific northwest. The remainder of the nation will have mostly sunny skies. Mild temperatures are in store for most of the middle and northern states, while it will be warm to hot across the south.

Almanac Data for today: The sun rises 6:26 a.m., sets 7:56 p.m.; moon rises 9:24 p.m., sets 8:54 a.m. Tides: high 10:19 a.m. and 10:49 p.m., low 4:38 a.m. and 5:02 p.m. High and low tides at the following locations may be obtained by subtracting the hours indicated from the hours above: Annapolis (3 1/2), 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 12 to 1 p.m. period was 115 for the pollutant, photochemical oxidants. Index values between 100 and 249 indicate 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 National Weather Service forecasts the Potomac River stage at Little Falls should fall to 3.8 feet today.

Washington data for yesterday: Highest temperature since midnight yesterday, 93 degrees at 3:39 p.m. Lowest temperature since midnight 74 degrees at 4:45 a.m. Excess of temperature since Aug. 1, 78 degrees. Deficiency of temperature since Jan. 1, 63 degrees. Record high temperature for today, 100 degrees in 1874. Record low temperature for today, 50 degrees in 1896. Relative humidity: maximum, 88 percent at 5 a.m.; minimum, 52 percent at 2 p.m. Excess of precipitation since Aug. 1, .49 inches. Excess of precipitation since Jan. 1, 3.18 inches. Highest observed wind since 8 a.m., 10 miles per hour from the south at 4 p.m. Local Temps. Humidity(TABLE) Time(COLUMN)T.(COLUMN)H. 12 midnite(COLUMN)79(COLUMN)74 1 a.m.(COLUMN)78(COLUMN)77 2 a.m.(COLUMN)77(COLUMN)79 3 a.m.(COLUMN)75(COLUMN)85 4 a.m.(COLUMN)75(COLUMN)85 5 a.m.(COLUMN)74(COLUMN)88 6 a.m.(COLUMN)74(COLUMN)88 7 a.m.(COLUMN)74(COLUMN)88 8 a.m.(COLUMN)77(COLUMN)82 9 a.m.(COLUMN)80(COLUMN)74 10 a.m.(COLUMN)83(COLUMN)67 11 a.m.(COLUMN)87(COLUMN)59 12 noon(COLUMN)90(COLUMN)54 1 p.m.(COLUMN)90(COLUMN)54 2 p.m.(COLUMN)91(COLUMN)52 3 p.m.(COLUMN)91(COLUMN)52 4 p.m.(COLUMN)92(COLUMN)52 5 p.m.(COLUMN)92(COLUMN)54 6 p.m.(COLUMN)92(COLUMN)54(END TABLE) Temperatures ending 8 a.m. (EDT) yesterday:(TABLE) City(COLUMN)H.(COLUMN)L. Albany(COLUMN)80(COLUMN)53 Albuquerque(COLUMN)93(COLUMN)68 Amarillo(COLUMN)91(COLUMN)62 Anchorage(COLUMN)74(COLUMN)56 Asheville(COLUMN)88(COLUMN)63 Atlanta(COLUMN)93(COLUMN)72 Atlantic City(COLUMN)83(COLUMN)67 Austin(COLUMN)99(COLUMN)75 Baltimores(COLUMN)88(COLUMN)68 Billings(COLUMN)74(COLUMN)51 Birmingham(COLUMN)92(COLUMN)72 Boise(COLUMN)77(COLUMN)56 Boston(COLUMN)855(COLUMN)65 Brownsville(COLUMN)97(COLUMN)79 Buffalo(COLUMN)84(COLUMN)70 Burlington(COLUMN)76(COLUMN)53 Casper(COLUMN)64(COLUMN)42 Charleston, S.C.(COLUMN)90(COLUMN)78 Charleston, W.Va(COLUMN)84(COLUMN)66 Charlotte(COLUMN)90(COLUMN)73 Cheyenne(COLUMN)64(COLUMN)43 Chicago(COLUMN)87(COLUMN)71 Cincinnati(COLUMN)86(COLUMN)71 Cleveland(COLUMN)90(COLUMN)73 Columbia, S.C.(COLUMN)95(COLUMN)67 Columbus(COLUMN)86(COLUMN)70 Dal.-Ft. Worth(COLUMN)102(COLUMN)79 Dayton(COLUMN)86(COLUMN)70 Denver(COLUMN)65(COLUMN)50 Des Moines(COLUMN)88(COLUMN)56 Detroit(COLUMN)87(COLUMN)71 Duluth(COLUMN)72(COLUMN)53 El Paso(COLUMN)98(COLUMN)75 Fairbanks(COLUMN)71(COLUMN)43 Fargo(COLUMN)72(COLUMN)43 Flagstaff(COLUMN)78(COLUMN)47 Great Falls(COLUMN)72(COLUMN)55 Hartford(COLUMN)81(COLUMN)55 Helena(COLUMN)73(COLUMN)44 Honolulu(COLUMN)88(COLUMN)72 Houston(COLUMN)94(COLUMN)79 Indianapolis(COLUMN)92(COLUMN)75 Jackson, Miss.(COLUMN)96(COLUMN)75 Jacksonville(COLUMN)95(COLUMN)69 Juneau(COLUMN)68(COLUMN)42 Kansas City(COLUMN)97(COLUMN)60 Las Vegas(COLUMN)96(COLUMN)69 Little Rock(COLUMN)100(COLUMN)78 Los Angeles(COLUMN)83(COLUMN)62 Louisville(COLUMN)90(COLUMN)76 Memphis(COLUMN)95(COLUMN)79 Miami Beach(COLUMN)87(COLUMN)84 Midland-Odessa(COLUMN)101(COLUMN)76 Milwaukee(COLUMN)85(COLUMN)67 Mpls.-St. Paul(COLUMN)81(COLUMN)55 Nashville(COLUMN)93(COLUMN)75 New Orleans(COLUMN)96(COLUMN)75 New York(COLUMN)86(COLUMN)69 Norfolk(COLUMN)89(COLUMN)69 North Platte(COLUMN)73(COLUMN)38 Oklahoma City(COLUMN)102(COLUMN)69 Omaha(COLUMN)79(COLUMN)50 Orlando(COLUMN)94(COLUMN)74 Philadelphia(COLUMN)87(COLUMN)68 Phoenix(COLUMN)105(COLUMN)84 Pittsburgh(COLUMN)84(COLUMN)64 Portland, Me.(COLUMN)85(COLUMN)55 Portland, Ore.(COLUMN)73(COLUMN)59 Providence(COLUMN)81(COLUMN)62 Raleigh(COLUMN)92(COLUMN)70 Rapid City(COLUMN)63(COLUMN)41 Reno(COLUMN)80(COLUMN)43 Richmond(COLUMN)92(COLUMN)68 St. Louis(COLUMN)97(COLUMN)70 St. Prbg.-Tampa(COLUMN)89(COLUMN)76 Salt Lake City(COLUMN)73(COLUMN)47 San Antonio(COLUMN)97(COLUMN)76 San Diego(COLUMN)77(COLUMN)68 San Francisco(COLUMN)77(COLUMN)56 San Juan(COLUMN)86(COLUMN)76 St. Ste. Marie(COLUMN)78(COLUMN)62 Seattle(COLUMN)69(COLUMN)57 Shreveport(COLUMN)101(COLUMN)74 Sioux Falls(COLUMN)70(COLUMN)49 Spokane(COLUMN)72(COLUMN)55 Syracuse(COLUMN)80(COLUMN)58 Topeka(COLUMN)97(COLUMN)60 Tucson(COLUMN)96(COLUMN)75 Tulsa(COLUMN)105(COLUMN)64 Washington(COLUMN)90(COLUMN)74 Wichita(COLUMN)101(COLUMN)63(END TABLE)(TABLE) City(COLUMN)Weather(COLUMN)Time(COLUMN)Temp. Aberdeen(COLUMN)pt. cldy(COLUMN)1 p.m.(COLUMN)64 Amsterdam(COLUMN)clear(COLUMN)1 p.m.(COLUMN)72 Ankara(COLUMN)clear(COLUMN)3 p.m.(COLUMN)77 Athens(COLUMN)clear(COLUMN)2 p.m.(COLUMN)86 Auckland(COLUMN)clear(COLUMN)12 a.m.(COLUMN)45 Berlin(COLUMN)clear(COLUMN)1 p.m.(COLUMN)68 Birmingham(COLUMN)clear(COLUMN)1 p.m.(COLUMN)73 Bonn(COLUMN)pt. cldy(COLUMN)1 p.m.(COLUMN)70 Brussels(COLUMN)clear(COLUMN)1 p.m.(COLUMN)73 Casablanca(COLUMN)pt. cldy(COLUMN)12 p.m.(COLUMN)75 Copenhagen(COLUMN)clear(COLUMN)1 p.m.(COLUMN)70 Dublin(COLUMN)rain(COLUMN)1 p.m.(COLUMN)61 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)82 Libson(COLUMN)clear(COLUMN)12 p.m.(COLUMN)82 London(COLUMN)clear(COLUMN)1 p.m.(COLUMN)73 Madrid(COLUMN)clear(COLUMN)1 p.m.(COLUMN)86 Malta(COLUMN)clear(COLUMN)1 p.m.(COLUMN)84 Moscow(COLUMN)clear(COLUMN)3 p.m.(COLUMN)75 New Delhi(COLUMN)cloudy(COLUMN)5 p.m.(COLUMN)86 Nice(COLUMN)clear(COLUMN)1 p.m.(COLUMN)77 Oslo(COLUMN)clear(COLUMN)1 p.m.(COLUMN)68 Paris(COLUMN)clear(COLUMN)1 p.m.(COLUMN)73 Peking(COLUMN)clear(COLUMN)8 p.m.(COLUMN)77 Rome(COLUMN)clear(COLUMN)1 p.m.(COLUMN)79 Saigon(COLUMN)pt. cldy(COLUMN)8 p.m.(COLUMN)86 Sofia(COLUMN)pt. cldy(COLUMN)2 p.m.(COLUMN)75 Stockholm(COLUMN)clear(COLUMN)1 p.m.(COLUMN)72 Sydney(COLUMN)rain(COLUMN)10 p.m.(COLUMN)55 Toyko(COLUMN)clear(COLUMN)9 p.m.(COLUMN)82 Tunis(COLUMN)clear(COLUMN)1 p.m.(COLUMN)82 Vienna(COLUMN)clear(COLUMN)1 p.m.(COLUMN)70 Warsaw(COLUMN)rain(COLUMN)1 p.m.(COLUMN)57(END TABLE)