To determine which moon phase it is tonight in the UK, we can consult various websites that provide information on the current moon phase. Here are some of the search results:

• According to, the current moon phase for today (October 31, 2023) is Waning Crescent, with 16.30% visibility. The next phase will be New Moon, which will occur in 4 days.

• also indicates that the current moon phase is Waning Gibbous, with 61.8% visibility. However, this information is from September 23, 2023, and it is unclear whether the website provides updated information on the current moon phase.

• provides information on the moon phase for September 21, 2023, which was Waning Crescent with 36.79% illumination.

Based on the above information, it is unclear which moon phase it is tonight in the UK. It is recommended to consult a reliable source that provides updated information on the current moon phase.