US Southwest (Las Vegas, Arizona) has two good windows: Feb–Apr and Oct–Nov. They sit either side of the season the climate record rules out, which is why the shoulder months matter here.
Arid; brutal summer heat
| Month | High °C | High °F | Rainy days | Verdict |
|---|---|---|---|---|
| January | 14.6 | 58 | 12% | Fair |
| February | 17.0 | 63 | 16% | Go |
| March | 21.4 | 71 | 12% | Go |
| April | 25.8 | 78 | 6% | Go |
| May | 31.5 | 89 | 3% | Fair |
| June | 37.8 | 100 | 2% | Too hot |
| July | 40.4 | 105 | 13% | Too hot |
| August | 39.4 | 103 | 12% | Too hot |
| September | 35.1 | 95 | 8% | Too hot |
| October | 27.6 | 82 | 7% | Go |
| November | 19.7 | 67 | 6% | Go |
| December | 13.9 | 57 | 9% | Fair |
Verdict combines mean daytime high with rainy-day frequency. “Rainy days” is the share of days in the month with at least 1 mm of rain.
June is the driest month, with rain on 2% of days and daytime highs near 37.8°C (100°F). February is the wettest, at 16%. Temperature swings hard across the year — 26.5°C between July (40.4°C / 105°F) and December (13.9°C / 57°F) — so packing for the wrong month is the main risk. The record rules out too hot in Jun–Sep.