Our stretch of cool and comfortable weather is coming to an end and quickly, too. Highs Saturday only reached the low and mid-80s, while Sunday brings about a 10° boost. The forecast high in Rockford is 92°, with heat index values reaching up to 105°. Our incredibly warm air mass is already starting to enter the area and will be here to stay in the coming days.

A “backdoor” cold front from the Northeast will slide through late Sunday, giving us a short reprieve from the heat Monday. Highs will still reach the upper 80s for most, but the highest area of dew points will shift to the Southeast. Galena, Savanna, Sterling, and other locations nearby may still see heat indices near 100° if the front stalls nearby.

With the heat incoming, the National Weather Service has issued some heat alerts for the week ahead. A HEAT ADVISORY goes into effect Sunday afternoon and evening for much of the Stateline. Within the advisory, head indices could reach 105°. To the Southwest, an EXCESSIVE HEAT WARNING begins Sunday and lasts into the middle of the week. Whiteside County is included in that warning for Sunday, where heat indices could reach 110°.

The Heat Advisory expires Sunday, but an EXCESSIVE HEAT WATCH is in effect for Carroll and Whiteside Counties starting Sunday night. It is very likely other areas in the Stateline will at least see additional Heat Advisories for the middle of the week, but they have not been issued yet.

Let’s talk temperatures now: The middle of the week looks to bring 3 days that would be the warmest day this year. So far, Rockford has only reached a high of 92° two separate times in both late June and late July. The days that concern me the most are Tuesday through Thursday, with highs reaching well into the 90s. Even if dew points are not in the mid-70s, this will still bring the heat index above 100° without much humidity. While we will not come close to any records, this will still be quite the hot and humid stretch. There is still a little uncertainty with how much humidity we may see toward the middle of the week. One of the question marks include any potential storm chances or storm outflows that may sneak into the Northern portions of the Stateline on the edge of the “ring of fire” pattern. Another question is how much mixing the surface air mass may be able to do with drier air aloft. If there is a lot of mixing, humidity would be much lower, but temperatures could be higher as a result.

While the high temperatures are the focus this week, even the overnight lows could still be quite humid, with some overnight lows not falling below 70°. It is very possible temperatures could still be in the 80s well after the sun sets most nights. The ridge bringing the heat does eventually break down late next week, with highs returning closer to normal for this time of year. As that ridge weakens, we could see some storm chances, mainly on Friday as a cold front slides through.

I also did a brief Facebook live on the heat and humidity for the week ahead summarizing this article. Feel free to watch, link here: https://fb.watch/mx62uIs-Ue/