Washington: Today -- Partly cloudy, high in the mid 70s, low in the mid 40s. The chance of rain is 10 per cent today and 20 per cent tonight. Monday -- Partly cloudy, high in the mid 70s.

Maryland: Today -- Variable cloudiness, high near 70, low in the 40s. Monday -- Variable cloudiness, high near 70.

Virginia: Today -- Variable cloudiness, high in the 70s, lows will range from the 40s to low 50s. Monday -- Variable cloudiness, high in the 70s.

Extended Area Forecast for Tuesday through Thursday -- Fair and warm through the period. Highs erature since 7 a.m. yesterday, 74 degrees at 3:35 p.m. Lowest temperature since midnight, 51 degrees at 5:30 a.m. Excess of temperature since April 1, 50 dewill average from the 70s to the low 80s and lows from the mid 40s to the mid 50s. Normal Washington temperatures for the period are a high of 69 and a low of 47.

Lower Potomac and Chesapeake Bay -- Today -- Fair with variable winds 10 knots or less through tonight. Visibility will be good. Waves will average less than 1 foot.

West Virginia: Today -- Mostly sunny, high in the 70s, lows will range from the mid 40s to mid 50s. Monday -- Partly cloudy, high in the 70s.

The Nation Yesterday: Flash flood watches continue for the northern and southern portions of Texas and for south central and southeast Kansas. A slow moving upper air disturbance has been producing showers and thunderstorms across these areas for several days. Thundershowers extended from the Texas Gulf Coast northward through the Plains into the upper Mississippi Valley and western Great Lakes. Late afternoon skies were cloudy in the shower areas and parts of the Pacific Northwest. Mostly sunny skies prevailed across the rest of the nation. The National Weather Forecast for today -- Showers and occasional thundershowers will extend over the upper Mississippi Valley, the lower Great Lakes, the southern and central Plains and the lower Mississippi Valley. Temperatures will be seasonably cool over the northwest corner of the nation and in the rainy areas of the Pains with mild to warm readings across the rest of the nation. Cloudy skies will be confined to the rain areas and sunny to partly cloudy skies will rule the rest of the nation.

Almanac data for Sunday, April 17: Sun rises 5:29 a.m., sets 6:47 p.m.; moon rises 5:02 a.m., sets 6:16 p.m.

Tides: High 7:32 a.m. and 7:54 p.m., low 1:41 a.m. and 2:10 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); Dealo, Md. (4 1/2); Colonial Beach (6); Norfolk (1 1/2); Virginia Beach (1); Solomons Island (6 1/2); Point Lookout (7).

The Council of Governments' Air Quality index for yesterday showed the high reading in the Washington area during the 10 A.M. period was 25 for the pollutant, photochemical exidants. Index values between 25 and 49 indicate fair air quality. 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 remain fair.

The National Weather Service forecasts that the Potomac River stage at Little Fails will remain near 4.3 feet.

Washington data at 7 p.m. (EST) yesterday: Highest temp-grees. Excess of temperature since Jan. 1, 31 degrees. Record high temperature for today, 93 degrees in 1976. Record low temperature for today, 26 degrees in 1875. Relative humidity: Maximum, 74 per cent at 2 a.m.; Minimum, 22 per cent at 5 p.m. 24 hour precipitation, None. Deficiency of precipitation since April 1, 28 inches. Deficiency of precipitation since Jan. 1, 4.35 inches. Highest observed wind since 7 a.m. 12 miles per hour from the northwest at 1:53 p.m. Peak gust since 7 a.m., 22 miles per hour from the northwest at 2:28 p.m.

Local Temp., Humidity (TABLE) Time(COLUMN)T.(COLUMN)H. 12 mid.(COLUMN)58(COLUMN)60 1 a.m.(COLUMN)56(COLUMN)66 2 a.m.(COLUMN)55(COLUMN)74 3 a.m.(COLUMN)55(COLUMN)59 4 a.m.(COLUMN)53(COLUMN)64 5 a.m.(COLUMN)52(COLUMN)63 6 a.m.(COLUMN)52(COLUMN)61 7 a.m.(COLUMN)53(COLUMN)57 8 a.m.(COLUMN)59(COLUMN)42 9 a.m.(COLUMN)62(COLUMN)39 10 a.m.(COLUMN)65(COLUMN)34 11 a.m.(COLUMN)67(COLUMN)32 12 noon(COLUMN)69(COLUMN)31 1 p.m.(COLUMN)71(COLUMN)27 2 p.m.(COLUMN)72(COLUMN)26 3 p.m.(COLUMN)73(COLUMN)24 4 p.m.(COLUMN)73(COLUMN)23 5 p.m.(COLUMN)73(COLUMN)22 6 p.m.(COLUMN)71(COLUMN)24 7 p.m.(COLUMN)69(COLUMN)24 8 p.m.(COLUMN)66(COLUMN)30 9 p.m.(COLUMN)62(COLUMN)41 10 p.m.(COLUMN)60(COLUMN)53 11 p.m.(COLUMN)60(COLUMN)53(END TABLE)

Temperature ending 7 p.m. (EST) yesterday: (TABLE) City(COLUMN)L.(COLUMN)H. Albany(COLUMN)35(COLUMN)62 Albuquerque(COLUMN)44(COLUMN)67 Amarillo(COLUMN)50(COLUMN)67 Anchorage(COLUMN)24(COLUMN)37 Asheville(COLUMN)45(COLUMN)80 Atlanta(COLUMN)53(COLUMN)85 Atlantic City(COLUMN)36(COLUMN)69 Austin(COLUMN)59(COLUMN)67 Baltimore(COLUMN)46(COLUMN)73 Billings(COLUMN)41(COLUMN)78 Birmingham(COLUMN)49(COLUMN)89 Bismarck(COLUMN)50(COLUMN)63 Boise(COLUMN)47(COLUMN)69 Boston(COLUMN)44(COLUMN)67 Brownsville(COLUMN)63(COLUMN)76 Buffalo(COLUMN)35(COLUMN)63 Burlington, Vt.(COLUMN)27(COLUMN)53 Casper(COLUMN)42(COLUMN)65 Charl'ton, S.C.(COLUMN)65(COLUMN)85 Ch'l'ton, WVa(COLUMN)48(COLUMN)76 Charlotte(COLUMN)53(COLUMN)82 Cheyenne(COLUMN)40(COLUMN)57 Chicago(COLUMN)54(COLUMN)84 Cincinnati(COLUMN)50(COLUMN)80 Cleveland(COLUMN)39(COLUMN)63 Columbia(COLUMN)58(COLUMN)82 Columbus(COLUMN)42(COLUMN)75 Dal. Ft. Worth(COLUMN)59(COLUMN)67 Dayton(COLUMN)47(COLUMN)60 Denver(COLUMN)41(COLUMN)65 Des Moines(COLUMN)53(COLUMN)84 Detroit(COLUMN)43(COLUMN)62 Duluth(COLUMN)39(COLUMN)62 El Paso(COLUMN)48(COLUMN)69 Fairbanks(COLUMN)08(COLUMN)30 Fargo(COLUMN)42(COLUMN)73 Flagstaff(COLUMN)24(COLUMN)67 Great Falls(COLUMN)42(COLUMN)74 Hartford(COLUMN)37(COLUMN)64 Helena(COLUMN)30(COLUMN)68 Houston(COLUMN)63(COLUMN)71 Honolulu(COLUMN)69(COLUMN)83 Indianapolis(COLUMN)55(COLUMN)83 Jackson(COLUMN)55(COLUMN)86 Jacksonville(COLUMN)50(COLUMN)86 Juneau(COLUMN)35(COLUMN)42 Kansas City(COLUMN)60(COLUMN)80 Las Vegas(COLUMN)53(COLUMN)86 Little Rock(COLUMN)61(COLUMN)84 Los Angeles(COLUMN)58(COLUMN)73 Louisville(COLUMN)55(COLUMN)83 Memphis(COLUMN)56(COLUMN)89 Miami Beach(COLUMN)72(COLUMN)80 Midland(COLUMN)50(COLUMN)62 Milwaukee(COLUMN)45(COLUMN)65 Mpls.-St. Paul(COLUMN)56(COLUMN)74 Naashville(COLUMN)54(COLUMN)87 New Orleans(COLUMN)59(COLUMN)84 New York(COLUMN)47(COLUMN)67 Norfolk(COLUMN)50(COLUMN)67 North Platte(COLUMN)50(COLUMN)68 Okla. City(COLUMN)59(COLUMN)73 Omaha(COLUMN)61(COLUMN)82 Orlando(COLUMN)56(COLUMN)85 Philadelphia(COLUMN)44(COLUMN)74 Phoenix(COLUMN)58(COLUMN)86 Pittsburgh(COLUMN)39(COLUMN)65 Portland, Me.(COLUMN)28(COLUMN)62 Portland, Ore(COLUMN)39(COLUMN)55 Providence(COLUMN)40(COLUMN)67 Raleigh(COLUMN)54(COLUMN)81 Rapid City(COLUMN)48(COLUMN)68 Reno(COLUMN)35(COLUMN)79 Richmond(COLUMN)44(COLUMN)77 St. Louis(COLUMN)56(COLUMN)88 St. Prbg.-Tam.(COLUMN)65(COLUMN)86 Salt Lake City(COLUMN)39(COLUMN)71 San Antonio(COLUMN)58(COLUMN)71 San Diego(COLUMN)57(COLUMN)64 San Fran.(COLUMN)48(COLUMN)62 San Juan(COLUMN)76(COLUMN)91 St. Ste. Marie(COLUMN)34(COLUMN)66 Seattle(COLUMN)41(COLUMN)54 Shreveport(COLUMN)61(COLUMN)83 Sioux Falls(COLUMN)55(COLUMN)73 Spokane(COLUMN)47(COLUMN)56 Syracuse(COLUMN)29(COLUMN)59 Topeka(COLUMN)53(COLUMN)82 Tucson(COLUMN)55(COLUMN)77 Tulsa(COLUMN)62(COLUMN)79 Washington(COLUMN)51(COLUMN)74 Wichita(COLUMN)55(COLUMN)63(END TABLE)

Temperatures Abroad Yesterday (TABLE) City(COLUMN)Weather(COLUMN)Time(COLUMN)Temp Aberdeen(COLUMN)rain(COLUMN)1 p.m.(COLUMN)52 Amsterdam(COLUMN)bt cldy.(COLUMN)1 p.m.(COLUMN)50 Ankara(COLUMN)Cloudy(COLUMN)3 p.m.(COLUMN)63 Athens(COLUMN)clear(COLUMN)2 p.m.(COLUMN)63 Auckland(COLUMN)cloudy(COLUMN)midnight(COLUMN)64 Berlin(COLUMN)rain(COLUMN)1 p.m.(COLUMN)45 Birmingham(COLUMN)cloudy(COLUMN)1 p.m.(COLUMN)52 Brussels(COLUMN)cloudy(COLUMN)1 p.m.(COLUMN)45 Cairo(COLUMN)clear(COLUMN)2 p.m.(COLUMN)81 Casablanca(COLUMN)cloudy(COLUMN)noon(COLUMN)64 Copenhagen(COLUMN)pt cldy.(COLUMN)1 p.m.(COLUMN)46 Dublin(COLUMN)cloudy(COLUMN)1 p.m.(COLUMN)48 Geneva(COLUMN)clear(COLUMN)1 p.m.(COLUMN)46 Hong Kong(COLUMN)pt. Cldy.(COLUMN)8 p.m.(COLUMN)79 Lisbon(COLUMN)cloudy(COLUMN)noon(COLUMN)57 London(COLUMN)pt. cldy.(COLUMN)1 p.m.(COLUMN)54 Madrid(COLUMN)cloudy(COLUMN)1 p.m.(COLUMN)57 Malta(COLUMN)clear(COLUMN)1 p.m.(COLUMN)63 Manila(COLUMN)clear(COLUMN)8 p.m.(COLUMN)84 Moscow(COLUMN)cloudy(COLUMN)3 p.m.(COLUMN)50 Nice(COLUMN)clear(COLUMN)1 p.m.(COLUMN)63 Oslo(COLUMN)snow(COLUMN)1 p.m.(COLUMN)34 Paris(COLUMN)clear(COLUMN)1 p.m.(COLUMN)50 Peking(COLUMN)cloudy(COLUMN)8 p.m.(COLUMN)55 Rome(COLUMN)clear(COLUMN)1 p.m.(COLUMN)61 Saigon(COLUMN)clear(COLUMN)8 p.m.(COLUMN)82 Sofia(COLUMN)rain(COLUMN)2 p.m.(COLUMN)39 Stockholm(COLUMN)cloudy(COLUMN)1 p.m.(COLUMN)63 Sydney(COLUMN)clear(COLUMN)10 p.m.(COLUMN)63 Tel Aviv(COLUMN)pt. cldy.(COLUMN)2 p.m.(COLUMN)73 Tokyo(COLUMN)pt. cldy.(COLUMN)9 p.m.(COLUMN)68 Tunis(COLUMN)pt. cldy.(COLUMN)1 p.m.(COLUMN)63 Vienna(COLUMN)pt. cldy.(COLUMN)1 p.m.(COLUMN)46 Warsaw(COLUMN)pt. cldy.(COLUMN)10 p.m.(COLUMN)48(END TABLE)

Temperatures (Western Hemisphere) (TABLE) City(COLUMN)Weather(COLUMN)High(COLUMN)Low Acapulco(COLUMN)fair(COLUMN)85(COLUMN)75 Barbados(COLUMN)cloudy(COLUMN)85(COLUMN)77 B ermuda(COLUMN)sunny(COLUMN)71(COLUMN)63 Calgary(COLUMN)cloudy(COLUMN)63(COLUMN)34 Culiacan(COLUMN)sunny(COLUMN)85(COLUMN)57 Edmonton(COLUMN)cloudy(COLUMN)64(COLUMN)25 Havana(COLUMN)cloudy(COLUMN)81(COLUMN)69 Kingston(COLUMN)cloudy(COLUMN)86(COLUMN)75 Montego Bay(COLUMN)cloudy(COLUMN)86(COLUMN)73 Mexico City(COLUMN)cloudy(COLUMN)72(COLUMN)46 Monterrey(COLUMN)sunny(COLUMN)(COLUMN)92 62 Montreal(COLUMN)clear(COLUMN)52(COLUMN)28 Nassau(COLUMN)cloudy(COLUMN)74(COLUMN)68 Ottawa(COLUMN)cloudy(COLUMN)57(COLUMN)34 Regina(COLUMN)cloudy(COLUMN)68(COLUMN)39 St. Kitts(COLUMN)cloudy(COLUMN)86(COLUMN)71 St. Thomas(COLUMN)cloudy(COLUMN)84(COLUMN)76 Toronto(COLUMN)clear(COLUMN)61(COLUMN)34 Vancouver(COLUMN)cloudy(COLUMN)52(COLUMN)43 Veracruz(COLUMN)cloudy(COLUMN)83(COLUMN)69 Winnibeg(COLUMN)clear(COLUMN)72(COLUMN)34(END TABLE)