The methodology used to weigh polls can be found here. By including polls in the average, no representation as to the accuracy or equivalency of the methods used is implied, nor should inclusion be seen as an acceptance, endorsement or legitimization of their results. The weighting scheme takes this partly into account. See here for a complete rundown of the latest polls in Ontario (external link).
The chart below shows the evolution of the weighted polling averages since July 2013 (note that the date listed is the final field date of the polling included in the aggregation at the time of the update).