pIt was so hot in Chicago on Saturday, June 30, that firefighters needed to hose down the Michigan Avenue Bridge to allow the bridge to open to let boats through because the steel in the bridge had expanded.ppTwitter user @ISaidData, who filmed this video, said firefighters needed to soak the bridge over the Chicago River for more than 30 minutes before it would open.ppTemperatures were in the mid to upper 90s on Saturday with heat indexes well over 100 degrees, according to the National Weather Servicea. The city also tied a record for the highest minimum temperature of 80 degrees on June 30, which was set in 1931.ppA heat wave was hitting much of the eastern part of the country on Saturday and through the weekend. The hot and humid weather was expected to continuea on Sunday in Chicago with a chance of severe stormsa in the afternoon and evening.