and favours the extensively operated viticulture. The annual average duration of sunshine amounts on 1638.7 hours. According to annual reports of the viticulture school Weinsberg, the average yearly temperature during 1961-1990 was , the annual precipitation was about . Values for the period 1971-2000 are at and 2002 at . January from 1961 to 1990 had on the average at precipitation, 1971-2000 at and 2002 at . July had from 1961 to 1990 on the average at precipitation, 1971-2000 at and 2002 at . According to meteorological data of the viticulture school the average yearly temperature in Weinsberg increased from 1900 to 2006 from to . History Prehistory and antiquity The earliest known settlement trace in Weinsberg is a group of tumuli. They're situated in the forest near the boundary to Heilbronn and haven't been investigated so far. It is assumed that the tumuli are to be assigned to the Hallstatt culture. In the 19th century there was found a Celtic silver coin from the 2nd century BC. Its inscription "V, O, L, C" can be assigned to the Celtic tribe of the Volcae, which lived (among other places) in Southern Germany at that time. So it can be assumed that Celts lived at least occasionally in the area of today's Weinsberg. However, the first solidly attested settlers in the area of Weinsberg were the Romans. In the 2nd century, a Roman road led through today's town, running from the Böckingen castellet (belonging to the Neckar Limes) to the Öhringen castellet (belonging to the Limes Germanicus). Between 148 and 161 AD, a Roman villa rustica was established on this road, which existed until its destruction by the Alamanni in 234 or 259/260. The bath house of this manor (known in Weinsberg as Römerbad, i.e. "Roman bath") was excavated and conserved in 1906; parts of the remaining manor followed in 1977. Middle Ages Around 500 AD, the Alamanni were displaced by the Franks, who settled on Weinsberg's communal land between Erlenbach and Gellmersbach in the 7th century. In 778 the area around Weinsberg was first mentioned as "Sulmanachgowe" in a deed of donation of Charlemagne to the Lorsch Abbey. In the area of today's Weinsberg several medieval settlements (Bodelshofen, Burchardeswiesen, Lyndach) were established, continuing even after the town foundation, but finally given up. Presumably around 1000, the Weinsberg castle was established on a mountain at the trade route running from Heilbronn