Monroe County, Illinois, read at county level: 8 ZIP codes and 0 communities inside the St. Louis metro's coverage, with the climate record and service pressures set out below. TempReach USA connects you with an independent local HVAC technician serving the county.
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The short version of this page: Monroe County runs to 385 square miles, its weather is the record kept at ST LOUIS LAMBERT INTL AP, MO US — 4,433 heating degree days, 1,713 cooling degree days — and its systems live under a heating pressure. One call to TempReach USA, a referral service rather than an HVAC company, connects you with an independent local HVAC technician serving the county.
Before the narrative, the numbers themselves, because everything after them is commentary: at ST LOUIS LAMBERT INTL AP, MO US, the station whose NOAA 1991-2020 normals this county is read through, an average year holds 47.1 days at 90 degrees or above, 84.9 nights at or below freezing, 41.7 inches of precipitation and degree-day totals of 4,433 heating against 1,713 cooling. Spread over 385 square miles, with the county's centroid southeast of the St. Louis metro's centre and roughly 33 miles from the centre it is measured against, that record is Monroe County's working climate.
There is a housing arithmetic under Monroe County's heating season. The metro it belongs to built its largest share of homes before 1960 — 33.8% of the stock — with the next share between 1960 and 1979 at 25.0%, around a median build year of 1973. Fitted into those eras, the county's furnaces and heat pumps meet 84.9 freezing nights at very different ages, and the heating diary divides accordingly: deep repair conversations in the older bands, first-replacement conversations in the newer ones.
The county's ground shapes the work in one more way: 385 square miles is a lot of roofs for a service map to hold, and Monroe County's homes divide between its listed communities — — and the roads between them. A technician routed here is working a county, not a street: the drive between calls is part of the diary, and the systems at each end of it were fitted in the decades those communities were built.
8 ZIP codes reach into Monroe County's 385 square miles, among them 62236, 62244, 62248, 62256 — an average of 48.2 square miles of county ground per code. The codes are more than a mailing grid here: they are how the county's service ground divides in practice, each code holding its own mix of housing eras, its own streets of systems ageing on their own schedules. A call in one code and a call in the next can be the same fault in different decades of house.
Read the map around Monroe County and a working region appears: Macoupin County, Madison County, St. Charles County, St. Clair County are the neighbouring names at the head of its list of 14, and together these counties form the ground a local technician actually covers. The county line decides which page describes a home; it does not decide the weather the home's system faces, the decade its street was built in, or the season its diary fills. Those are regional — and the region, on this site, is a set of county pages that link to one another, as the cards below do.
Consider what one year asks of a system in Monroe County: a cooling season measured at 1,713 degree days, a heating season at 4,433, 47.1 days of serious heat and 84.9 freezing nights, and 41.7 inches of precipitation working on every outdoor unit through all of it. No single figure is remarkable; the combination is the county's climate, and it is the combination a system has to survive for fifteen or twenty years. The service patterns described on this page are that arithmetic, playing out across 385 square miles of housing.
Hold Monroe County up against its own neighbours and the missing place list stops looking like a gap. Macoupin County, Madison County, St. Charles County are among the 14 counties around it; some of them are lists of named towns, this one is 385 square miles of ground lying southeast of the St. Louis metro's centre, roughly 33 miles out. Its communities exist — people live in them, heat them, cool them — but the record reaches them through the county's ZIP codes rather than through names, and this page follows the record's way of seeing.
Census figures give Monroe County's heating and cooling its proportions. The metro it belongs to counts 1,267,353 housing units across 1,154,841 households, 70.1% of them owner-occupied, and the era mix runs 33.8% before 1960, 25.0% from 1960 to 1979, 22.7% from 1980 to 1999 and 18.5% since 2000. A county inside that metro inherits the mix in its own proportions — which is why two homes on the same Monroe County street, built forty years apart, can need entirely different conversations from the same technician.
One way to hold Monroe County in mind is as the local layer of a wider dataset. Above it sits the St. Louis metro, with its Census housing profile and its NOAA station at ST LOUIS LAMBERT INTL AP, MO US. At this level sit the county's own numbers — 385 square miles, 14 neighbouring counties, 8 ZIP codes, 0 listed places — and below it, not published anywhere, sit the individual homes whose systems all of it describes. This page works at the middle level, where the data is still local enough to act on.
City pages carry the metro-wide homework — housing eras, the problem ranking, services in depth. This county sits inside their coverage.
TempReach USA is not an HVAC company. We employ no heating or cooling technicians, we run no service trucks, and we do not carry out HVAC work of any kind. This website and its call center exist for one purpose: to connect homeowners with independent local heating and cooling professionals who serve their area. When you call the number on this site, your call is routed to such a professional. From that point, everything about the job belongs to that professional and to you: the assessment, the work itself, the scheduling, what you are charged, and the terms of any agreement you reach. The professional who takes your job is solely responsible for it. The technician who arrives at your home runs their own business; they are not an employee, agent or subcontractor of TempReach USA. Our part is the information on these pages — assembled from Census Bureau housing data and NOAA climate records for each metro — and the routing of your call. We state this plainly on purpose: you should know exactly who you are hiring before anyone picks up a wrench or a gauge.
One call connects you with an independent local heating and cooling professional serving Monroe County and the St. Louis metro.
Call center hours: Mon-Fri 7:00 AM-10:00 PM ET | Sat 8:00 AM-10:00 PM ET | Sun 7:00 AM-9:00 PM ET