In construction, total labor productivity is determined by the quality of effectively combining elementary production factors. For labor-intensive activities, one of the most important elementary factors is the people that the achievable labor productivity depends on. In respect of the circumstances under which they perform work, there are optimal weather conditions that meet the requirements for being capable of achieving normal output. To record the influence of temperature on labor consumption rates and labor productivity in masonry works, an expert survey was conducted in Austria and Germany, which included a total of 35 respondents from construction contractors (from both construction trades and industry; survey period: August 2012 to April 2013). The average professional experience of respondents equaled 17 years (minimum experience: five years; maximum experience: 43 years). Filled-in questionnaires were analyzed using an exploratory data analysis. This paper outlines the statistical bases for Huber’s M-estimator method, which was successfully applied in this analysis. Box plots of the variables were used to graphically represent distributions. A box plot describes the position and spread of a distribution and provides information with respect to any outliers or extremes. Initially, the optimal daily temperature for achieving the highest possible labor productivity was determined. Subsequent work steps involved the documentation of changes in labor productivity that occurs if temperatures deviate from their optimal range.