Summary:

Occurence of minus air temperature, precipitation and wind worsen tech-nical conditions of the performance of maintenance works and it also has an impact on the occupational safety. Some of the results of considered weather events are the delays in the performance of particular works and an increase of their costs in a result of additional works. Potential financial loss that may influence enterprise in a result of unfavourable weather conditions is determined as the weather risk. In the following research the level of the risk in maintenance works in watercourses was assessed. The analysis of the weather forms was conducted in Wrocław between 2000 and 2011 for that purpose. Three weather conditions such as the air temperature below 0, rainfall, snowfall and the velocity of the wind were considered. Analysis was conducted basing on the data obtained from the Wroclaw Airport station. It was performed for the period recommended for the performance of maintenance works in watercourses from the 1st to the 31st of December.
Frequency of the days occurence while weather conditions constituted an obstacle was determined basing on the obtained data. The analysis revealed that unfavourable weather conditions occurred often in realization of the works in the considered period of time. The data suggests that the greatest risk in the perfor-mance of maintenance works occurs in November while in September and October it is lower. It was also reported that in December maintenance works shouldn`t be performed.