In an announcement, the court urged Muslims who sight the moon by the naked eye, or through binoculars to report to the nearest court and register their testimonies, or report to the nearest centre that can contact a court.
Ramadan is the ninth and holiest month of the Islamic — or Hijri, calendar. It is also believed to be the month the Quran was revealed to the Prophet Mohammed.
Muslims fast from sunrise to sunset every day of the month, which is typically either 29 or 30 days.
If the moon is observed over the kingdom on Friday, the holy month will begin the next day. If not, it will start on Sunday.
The Muslim world typically looks to Saudi Arabia when it comes to deciding the days on which major religious events fall, including the start of Ramadan and Eid Al Fitr, which marks the end of the holy month.
The kingdom announced on Monday restrictions on volume levels for loudspeakers at mosques during Ramadan.
Speakers must not exceed a third of their full volume, the Ministry of Islamic Affairs said.
Officials have asked mosque staff to ensure they abide by circulars that limit the use of external loudspeakers for the first (adhan) and second (iqamah) calls to prayer.
Speakers cannot be used for additional prayers during the holy month.