Utah AgWeather is a network of approximately 54 automated weather stations operated by the Utah Climate Center to provide weather data and reference evapotranspiration to help Utah municipalities, farmers and ranchers, and those managing turfgrass make informed water management decisions. Several stations provide data critical to university and state agency research. The network has a statewide distribution with stations sited in irrigated and dryland agricultural, turfgrass, fruit, and native riparian vegetated areas. Stations have research grade sensors that measure solar radiation, wind, pressure, relative humidity, air and soil temperature, precipitation, and soil moisture.

Reference ET is calculated by the ASCE standardized reference ET equation (ASCE-EWRI 2005) - often referred to as the Penman-Monteith method. This method calculates an estimated reference ET for both short crops (similar to clipped grass) (ETo) and tall crops (similar to full-cover alfalfa) (ETr). The calculations are made utilizing individual site level information (latitude, longitude, and altitude) and measured variables (air temperature, humidity, wind, and solar radiation). Since actual ET (Eta) is both difficult and expensive to measure, a crop ET (ETc) can be calculated by the user as the product of ETo or ETr. Obtaining crop coefficients for specific crops and growth stages can be obtained from a variety of sources. The choice of whether to utilize ETo or ETr largely depends on the overall crop height.