By: Rabbi Ari Enkin
It is well-known that one is forbidden to use an umbrella on Shabbat. This is because the use of an umbrella is considered to be a violation of the melacha of “boneh”, the prohibition of erecting any type of tent, structure, or protective covering. In fact, the use of an umbrella might even be a violation of a number of other Shabbat prohibitions, as well. An umbrella may not be used on Shabbat even if it was opened before the start of Shabbat. This is primarily due to the prohibition of ma’arit ayin (“the appearance of a sin”) lest onlookers be led to believe that one had opened the umbrella on Shabbat itself.
It is interesting to note that the Chatam Sofer was of the opinion that it is essentially permissible to use an umbrella on Shabbat. He argued that an umbrella is only a “temporary structure” and as a general rule only permanent structures are forbidden to be assembled on Shabbat. He also notes that since an umbrella is portable, not fastened to the ground, and has no walls, it cannot be considered a structure which should be forbidden, at all.
There are other possible reasons for permitting the use of umbrellas, as well. It is argued that an umbrella should be no different than a folding chair which is permitted to be opened and closed on Shabbat. However, others disputed this assumption arguing that a folding chair is not comparable to an umbrella. This is because an umbrella is opened with the express intention that it serve in a protective (“tent-like”) manner in order to protect one from the elements. A chair, on the other hand, does not serve in a similar capacity. It is also noted that a chair folds and unfolds directly into the desired position. An umbrella, however, must be fastened or locked into place in order to assume the desired position.
Even though there have been authorities in the past who supported the use of umbrellas on Shabbat, the familiar ban on using them is one which has been universally accepted. In fact, the Chafetz Chaim writes that “one who is careful with his soul will refrain from using them”. Not only is it forbidden to use an umbrella on Shabbat, but they are muktza and may not even be moved. Furthermore, our sages decreed that one should avoid assembling all forms of tents and canopy-like structures on Shabbat, even permitted ones, lest it lead to handling forbidden ones. Nevertheless, one need not overly rebuke those less-learned who use an umbrella which was opened before Shabbat. One may open and close garden umbrellas on Shabbat which are permanently implanted into the ground or some other base.
……..with prayers for a very wet winter in Eretz Yisrael
 Noda Beyehuda, OC 1:30.  Chazon Ish, OC 52:6.  Shemirat Shabbat K’hilchata 24:15 note 53.  Chatam Sofer, OC 72.  Biur Halacha 315:7.  Rivevot Ephraim 7:105, 2:115:61.  Biur Halacha 315:7.  Shemirat Shabbat K’hilchata 24 note 54  Rambam, Hilchot Shabbat 22:27  Salmat Chaim 295.  Shemirat Shabbat K’hilchata 24:15