To say that the weather is changeable is an understatement. But don't let this deter you. Plan to dress in layers so that you can peel as necessary. These are ultra light and fold down to practically nothing. While sandles are nice to wear during the summer, the changeable weather here means that your feet could be wet much of the time.
Closed shoes make much more sense.
Although israel is boiling hot in the summer, you must wear a long skirt and long sleeves to get into most of the religious sites. This is good for visiting religious sites AND for walking in the sun. It gets quite hot here. This outfit will get you into the religous sites and keep you from being hassled by the more traditional or religious folk. Alexy, Hamilton, New Zealand Shorts and miniskirts are inappropriate for visiting the sacred sites of all the religions, Jewish, Muslim and Christian.