Aemet, who on Monday forecast a change in the weather at the end of the week, now says that there will be a "radical change".
The met agency says that on Saturday there will be "storm clouds and rain". The storms could be "locally heavy", especially in the north of the Balearics archipelago.
Temperatures are forecast to drop to 27C or lower over the weekend. A strong north wind on Saturday will produce rough sea conditions.
For Wednesday to Friday, highs are forecast to continue to be around 36C.