Although freezing temperatures have been recorded across most of southern MB by now, the growing season continues in downtown Winnipeg which has still to register a below freezing temperature so far this fall. The lowest temperature so far at the Forks weather station downtown has been 0.3C on Oct 17th. This morning, while the temperature at Winnipeg airport dropped to a chilly low of -4.8C, the Forks station recorded a low of +1.5C, over 6 degrees warmer than the airport site. This difference is due to a phenomenon known as the "urban heat island" effect, which basically keeps temperatures (especially nighttime temperatures) warmer in a downtown core compared to nearby rural areas which can lose heat to the environment more effectively. This prolongs the average growing season downtown by 2-4 weeks compared to the airport site.