A weather system from Canada will likely descend this weekend, bringing cooler temperatures to Louisville.Temperatures have been above average for most of September and rainfall has been unseasonably low. National Weather Service meteorologist Ryan Sharp says the weather system will likely arrive on Sunday, causing lower temperatures and possibly rain."It depends on where that low lands, whether it's over Missouri or over east Kentucky," says Sharp. "If it's over Missouri, we're most likely going to get quite a bit of rain, but if it lands over eastern Kentucky, then we may not get anything but cooler weather."Sharp says temperatures will be average for this time of year next week. That means highs will be in the upper 70s and lows will be in the upper 50s.