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Climate change constitutes amajor challenge for high productivity in wheat, the most widely grown crop in Germany. Extreme weather events including dry spells and heat waves, which negatively affect wheat yields, are expected to aggravate in the future. It is crucial to improve the understanding of the spatiotemporal development of such extreme weather events and the respective crop-climate relationships in Germany. Thus, the present study is a first attempt to evaluate the historic development of relevant drought and heat-related extreme weather events from 1901 to 2010 on county level (NUTS-3) in Germany. Three simple drought indices and two simple heat stress indices were used in the analysis. A continuous increase in dry spellsover timewas observedover the investigated periods from 1901-1930, 1931-1960, 1961-1990 to 2001-2010. Short andmediumdry spells, i.e., precipitation-free periods longer than 5 and 8 days, respectively, increased more strongly compared to longer dry spells (longer than 11 days). The heat-related stress indiceswith maximum temperatures above 25 and 28 °C during critical wheat growth phases showed no significant increase over the first three periods but an especially sharp increase in the final 1991-2010 period with the increases being particularly pronounced in parts of Southwestern Germany. Trend analysis over the entire 110-year period using Mann-Kendall test revealed a significant positive trend for all investigated indices except for heat stress above 25 °C during flowering period. The analysis of county-level yield data from 1981 to 2010 revealed declining spatial yield variability and rather constant temporal yield variability over the three investigated (1981-1990, 1991-2000, and 2001-2010) decades. A clear spatial gradient manifested over time with variability in theWest being much smaller than in the east ofGermany. Correlatingyield variability with thepreviously analyzed extreme weather indices revealed strong spatiotemporal fluctuations in explanatory power of the different indices over allGermancounties andthe three timeperiods.Over the30years, yield deviations were increasingly well correlated with heat and drought-related indices,with the number of dayswith maximum temperature above 25 °C during anthesis showing a sharp increase in explanatory power over entire Germany in the final 2001--2010 period. [ABSTRACT FROM AUTHOR]