Chicagoans can expect a chilly Thanksgiving holiday weekend, with a chance of rain or snow overnight Wednesday. Temperatures for Turkey Day itself are expected to be in the upper 30s, with a predicted high of 40 degrees,according to the National Weather Service. A weather system passing through Wednesday night could also bring rain or snow, with the potential to last into Thursday morning, according to National Weather Service meteorologist Ricky Castro. Here’s when Chicago received its first snow of the fall season, going back more than 135 years Any precipitation on Thanksgiving Day is more likely to be rain, Castro added, although he “can’t rule out” snow Wednesday night for those traveling before the holiday. “As far as whether there could be precipitation or not, it’s a little too early to say,” Castro said. “But (there’s) pretty high confidence that we’re going to be in a colder pattern for Thanksgiving. So, what that means is nothing too crazy temperature wise, but certainly not mild weather, either.” Overall, the week of Thanksgiving should bring a “return to colder conditions” after milder weather in the low 50s on Sunday, Castro said. A cold front is expected to come through the Chicago area Monday that will lead to lower temperatures as Thanksgiving approaches, according to Castro. After the holiday weekend, Castro said that a “pretty cold start to December” appears likely, with even colder air coming into the region. “(This) would be a change from previous Decembers that were exceptionally mild, a lot of the Decembers we’ve had lately,” Castro said. “Actual winter weather in time for meteorological winter appears likely this year, at least from a temperature standpoint.” These colder patterns will bring “occasional chances for accumulating snow,” he added, with Thursday’s snowfall being the season’s first “wake-up call that we’re in northern Illinois.” “It’s been a warm fall, but it does not look like that’s going to be the case as we move to close out November into December, definitely,” Castro said. Chicago weather: What’s normal for fall’s first freeze and first snow? And when does it happen?