It will be very hot and humid for the third day. A weak cold front will approach from the north and spark a line of thunderstorms, but these storms are not projected to reach New Castle County until the early evening. At that point, it will likely be too late in the day to limit ozone production. A slightly cooler and less humid air mass will build in for Sunday and Monday and the arrival of this new, clean air will drop ozone down into the low end of the Moderate range and push particles lower in the Good range.