Depressed Dew Points in Vegas

Folks in the US Southwest jest about the 'dry heat' factor when temperatures are over 100 degrees during June and July. When dew point values are low, evaporation is sufficient enough to allow temperatures to feel a few degrees cooler than the actual air temperature. In Las Vegas Monday, the dew point-temperature differential was the largest it had been on record for them....129 degrees (see the last line of the photo below).

The temperature was 107 late Monday afternoon in Vegas while the dew point was a thirst-inducing -22.    Even in the most arctic of airmasses locally our dew point levels will rarely get below -15 in the dead of winter...a -22 dew point is even rare for the high desert in the heat of summer.    The culprit?   My guess is that gusty winds that downsloped off of mountains to Las Vegas' south and southwest yesterday played a role in the huge dew point-temp differential, allowing the air to dry out further and warm up more.

With the dew point factored in, the heat index in Vegas yesterday afternoon was in the mid to upper 90's at the height of the dew point drop.   Hardly comfortable but certainly better than 107!