1. A method, comprising: receiving, at a computing device, a plurality of geofence-status indications, wherein at least one geofence-status indication of the plurality of geofence-status indications comprises training data associated with a geofence at a first location, wherein the training data comprises signal strength information from one or more networks at the first location, and wherein the geofence is associated with a geographical area; training a geofence-status classifier of the computing device to determine a status of the geofence by providing the training data as input to the geofence-status classifier, wherein the training data comprises data for each of a plurality of training features, wherein the plurality of training features comprise a training feature associated with the signal strength information from one or more networks at the first location, and wherein the geofence-status classifier comprises a plurality of decision trees; after the geofence-status classifier is trained, receiving query data associated with a second location at the computing device, wherein the query data comprises data for each of a plurality of query features, wherein the query data comprises signal strength information from one or more networks at the second location, and wherein the plurality of query features comprises at least one query feature associated with the signal strength information from one or more networks at the second location; providing the query data as input to the trained geofence-status classifier; and after providing the query data as input, indicating the status of the geofence using the trained geofence-status classifier by at least: providing the query data to at least a subset of the plurality of decision trees; after providing the query data, determining one or more output values from the at least the subset of the plurality of decision trees; and determining the status of the geofence by at least aggregating the one or more output values.