Now, these are the official recorded temps from the airport going back to 1937. Certainly it's possible other parts of Vegas have been hotter at some point.

Maximum 1-Day Mean Max Temperature
for Las Vegas, NV (ThreadEx).
1 117.0 2021-07-10
- 117.0 2017-06-20
- 117.0 2013-06-30
- 117.0 2005-07-19
- 117.0 1942-07-24
6 116.0 2023-07-16
- 116.0 2021-07-09
- 116.0 2021-06-16
- 116.0 2017-07-07
- 116.0 2007-07-05
Last value also occurred in one or more previous years.
Period of record: 1937-01-01 to 2024-07-06

Maximum 1-Day Mean Max Temperature
for Phoenix Area, AZ (ThreadEx)
1 122.0 1990-06-26
2 121.0 1995-07-28
3 120.0 1990-06-25
4 119.0 2023-07-25
- 119.0 2023-07-20
- 119.0 2023-07-19
- 119.0 2017-06-20
- 119.0 2013-06-29
9 118.0 2024-07-05
- 118.0 2023-07-26
Last value also occurred in one or more previous years.
Period of record: 1895-08-06 to 2024-07-06