The latter half of May was cool and damp. At O’Hare International Airport, rain was observed on 10 of the month’s last 14 days. Thursday marked the start of the meteorological summer season. Fittingly, the day averaged 2 degrees above normal, due largely to bright sunshine. The day produced 100% of its possible sunshine, the first time that has happened since May 7th. Temperatures reached 80 degrees most areas. More 80-degree weather is on its way. Computer forecasts are in close agreement in bringing a weather system across the upper Great lakes over the upcoming weekend. This feature will draw moist, tropical air into the region by Saturday, sending temperatures into the mid 80s. The higher humidity is expected to support thunderstorm development, especially Saturday night.