Industrial Excess Heat (IEH) is an underutilised resource which could contribute to decarbonising the heat supply. It is particularly well suited for supplying district heat networks (DHN), thereby enabling the capture and distribution of excess energy from industries and incineration plants. However, as heat cannot be readily transported over long distances, there is a need to analyse the balance of supply and demand over time taking into account the geospatial constraints placed on the linking of IEH supplies and DHN demands. This work presents an analysis of the potential for the supply of DHN systems using high and low network temperatures by IEH in Switzerland. A spatial clustering method is used to link potential supplies and demands, and monthly supply and demand curves are used to calculate the potential for IEH supply subject to spatiotemporal constraints. A further analysis deals with the technical potential for seasonal storage to shift surplus IEH energy from summer to winter. A total resource of 12TWh/y of IEH was found, but spatial and temporal constraints limited its utilisation to between 7.7TWh/y and 10.5TWh/y depending the scenario considered. 17.4% of total heat demand could be supplied by IEH using low temperature DHN and seasonal storage.