The paper estimates an irrigation water demand function using disaggregate climate and well data over a 32 year time period. Aggregating climate information over long periods, like a year, loses important details on temporal climatic variation, while aggregating climate information over space loses important details on spatial variation. This analysis uses disaggregate climate variation at a temporospatial level to determine the effects of climate on groundwater use. Results show that increased heat, measured in cooling degree-days, correlates with increased water use, while increased precipitation correlates with decreased water use. However, the effects are generally magnified for later summer months, and are generally lower earlier in the growing season, with a few notable exceptions. Other factors that significantly affect groundwater irrigation demand are soil type, the price of corn, pumping rate, and the number of certified irrigated acres.