The Temperature-Humidity Index (THI) is used as a basis for communicating the level of heat stress hazard for feedlot cattle. Declines in rates of animal production, feedlot cattle deaths, and heat wave categories have been defined based on the magnitude and/or the extent of high THI periods. Three categories of THI have been developed and used as an operational environmental management tool for feedlot operators, alert (THI from 75 - 78), danger (THI from 79-83) and emergency (THI greater than 84). Using hourly observations of temperature and humidity from weather stations in Missouri, Iowa, Nebraska, and Kansas (the MINK region), this research is developing a number of applied climate products designed to help test the validity of existing conceptual, statistical, and process models that relate livestock production and health to accumulating heat stress. Data being used are from the Surface Airways data set and summary statistics being generated include: THI hours (above a threshold, such as 75) per day, per month, and per year. Initial results for Wichita, Kansas, indicate that THI values exceeding 75 can occur at any hour throughout the day with greatest likelihood in late afternoon. July is the month of highest frequency of THI alert conditions. Assessment of year-to-year differences in THI hours per year indicates that (for THI greater than 75) THI hours/year range from over 1400 (occurring on over 120 days) to less than 900 (on less than 90 days). Additional summary statistics will include an assessment of nighttime recovery potential using minimum THI values during the diurnal cycle and measures that assess heat wave duration using an accumulation THI over several days.