We're further south of Durango, though higher up. Our last freeze is usually at the beginning of June. It would be surprising
not to have mornings with freezing weather in April or May.
Of course, if a 'real' storm moves in, then the freeze could last more than just an hour or so.
I wouldn't sweat it if the temps drop below freezing for an hour or two in the morning. If you are concerned, just disconnect and drain your water hose before you go to bed, and reconnect it when the temps are above freezing. Turn your thermostat on low and hit the sack.
Lynn