Abstract
Since 1988, what appears to be an abnormal number of maximum temperature records has been set at the National Weather Service Office in Tucson, Arizona (TUS). We present several analyses that indicate that the current measurement system at TUS is indicating daytime temperatures that are 2 to 3 degrees too high. It appears that the instrument is not appropriately aspirated so that, during the day, temperature readings are significantly warmer than ambient air temperatures, while at night they are slightly cooler. The system at TUS is similar to one that has been installed at many National Weather Service sites around the country. We speculate on the impact this system may have on the climate record if the errors noted at Tucson are similar at the other sites.
