new dress, heat wave-proof

My cousin is getting married this Sunday, in New Rochelle (home of Dick van Dyke and Mary Tyler Moore, you know the place). Today it is 100 degrees in the shade in NYC. Tomorrow it will be 101. Thursday it will be 99. Yesterday was 99. You would think that the heat will break just in time for their nuptuals to be a lovely cool and breezy affair on Long Island Sound.But I am not taking any chances