The high temperature at both O’Hare and Midway airports reached 92 degrees on Monday, the result of ample sunshine and southwest winds that gusted over 30 mph. Officially, this was the 9th day this year that readings climbed to 90 or higher. Much more uncommon are 100-degree days. Since 1871, the city has logged only 65 such occurrences, most recently in 2012. Clouds and perhaps a few showers will keep readings lower on Tuesday, especially south and east of the city. Sunshine is to return midweek, prompting a more 90-degree heat. Forecasts are in close agreement in developing a major blast of heat beginning Thursday, and continuing over the weekend. Highs may reach 100 degrees at some locations as early as Thursday, especially within the city’s heat island. The most intense heat is forecast to sweep into the area Friday and Saturday when triple-digit readings are most likely area-wide.