The news in Colorado is highlighting the 105°F temperature recorded at Denver International Airport as tieing the all-time Denver record. However, the Airport site was established in 1995. Thus, we do not know if this was a long-term temperature record at this site. Other sites in eastern Colorado were hot, but they did not all exceed an all-time record (the Fort Collins observing site, for example, did not even reach 100°F yesterday, although it was still hot!). An accurate media perspective of this “all-time record” value is given in this Rocky Mountain News article.
This heat wave again illustrates why we also need to monitor moist enthalpy as discussed in the posting of July 18th . The dewpoint temperatures were in the upper 20s F, while the temperature was in above 100°F at the airport. The actual heat content of the air should also be included when discussing heat waves.
The answer to the question is that the official site for the Denver measurement tied its all-time record temperature. However, the location of this official measurement has moved over time, so we really do not know whether it really is the day with the highest temperature for the city in general. At the Colorado Climate Office, we will collect the data from around the state to place this heat wave in context (we expect to report on this in August after all of the data arrives from the cooperative weather observers). In terms of heat in the air (moist enthalpy) we recommend that this important climate metric be also tracked to really determine what is the hottest day.