In the high desert of the US southwest (6000'/1800m and above), it is not unusual to see diurnal temperature swings of 30F/16C or close to it. It's completely normal for at least 2 seasons a year to need an insulated jacket in the morning and evening, a light sweater just after and before the jacket is removed/added, and a t-shirt or similar for the middle of the day. Of course, the chance of rain is close to zero outside of any monsoon season that may or may not occur.
I'm in the southwest at 5000', and if anything you're understating it. To choose convenient arbitrary samples: Tomorrow 40°F low / 82°F high (42°F delta); Saturday 45°F low / 90°F high (45°F delta). Even 60°F swing isn't unheard of.
Ditto: I'm in the southwest (SE AZ) at 4700': Tomorrow 58°F low / 90°F high (32°F delta); Saturday 61°F low / 94°F high (33°F delta). An approximate 30°F diurnal swing is pretty much the norm year-round here. Your comment about precip and monsoon season applies too.
