It is looking more and more like we may set a record for the earliest 100 deg. day for Las Vegas.

From the Las Vegas Review Journal;

The upcoming heat wave that will pick up Tuesday is expected to bring temperatures that could surpass 100 degrees, an unprecedented high that is months ahead of schedule. The average daytime high for the valley in mid-March is in the low 70s, while the earliest 100-degree day of the year reached in Las Vegas was May 1 in 1947…
An extreme heat watch takes effect Thursday morning when Las Vegas could see a historic first 100-degree day in March. Friday is expected to be even hotter.