The growth and development of field crops are strongly affected by weather conditions. The aim of the present study was to evaluate the influence of temperature, solar radiation, precipitation and leaf area index on the development of sugar beet yield Germany. In 2000 and 2001, a series of trials were carried out at eleven locations in Germany that have different climatic and soil conditions. Between May and October, sequential field samples were taken every second or fourth week, and leaf area index, root yield and sucrose concentration were determined at each harvest date. For all locations, daily weather data were recorded and growth analyses were carried out. Until the end of June, sugar yield increased strongly with thermal time. The daily increment in sugar yield was mainly controlled by leaf area until the end of August, and by radiation intensity during the last weeks of the growing season. The impact of water supply on yield development was assessed at a location with both rainfed and irrigated beet. Additional sprinkler irrigation clearly increased the daily increment in sugar yield.