ROCKFORD (WREX) — High pressure is building late this week, keeping the overall weather tranquil. Sinking air is leading to building heat as the week comes to a close in time for the 4th of July weekend.
Stretch of 90°+ days:
The forecast for the next seven days show no signs of breaking up the 90° and higher heat. On average, Rockford records 15 days a year where high temperatures get to or above 90°. So far in 2020, Rockford has observed eight, seven of which fell during the month of June.
July, which started Wednesday, is typically the month where the Stateline gets the warmest daytime high temperatures. As a ridge continues to build in the upper-atmosphere, sinking air keeps the warmer weather around. As a reminder, when air sinks, or compresses, it warms.
High temperatures are going to remain near and above 90° over the next seven days, but does that qualify as a heat wave? The official definition of a heat wave is a stretch of more than five consecutive days where max temperatures are at least 9° higher than average. Average temperatures in Rockford for early July are in the middle 80s, so the stretch of warm days won't technically qualify as a heat wave.
Holiday weekend outlook:
It wouldn't be July without some heat, right? Normally, heat and humidity lead to at least some late-day pop-up storms. That doesn't look to be the case with this particular pattern. Storm chances remain very limited, despite the normally favorable conditions for development.
The one day late this week which could bring a shower or two to the Stateline is Friday. Models continue to keep most areas dry and even the forecast early Thursday morning has no precipitation chances for Friday.
Saturday is the 4th of July and it is going to be dry and sunny. While Mother Nature might not provide fireworks of her own, fireworks shows should go off without a hitch.