A standby generator needs a few extra steps before a North Shore winter sets in. Switch to synthetic 5W-30 oil if your model calls for it, add a cold weather kit once nights start dropping near freezing, keep the unit clear of snow and ice, and check the battery before the first hard cold snap. Skipping this prep is one of the most common reasons a generator fails to start during a January outage, right when a downed ComEd line in Winnetka or Glenview leaves a house running on nothing but a furnace fed by Nicor or North Shore Gas. Most of the work below takes less than an hour a year and costs far less than an emergency service call during a blizzard.
This guide covers generator upkeep specifically. For the rest of your home, from frozen pipes to a stocked emergency kit, see our full winter power outage prep guide. If you do not have a generator yet, our guide to the best time to install one in Chicago covers the months that beat the storm season rush.
Why Winter Is Hard on a Standby Generator
Cold engine oil thickens and cranks slower, batteries lose a big share of their starting power in freezing temperatures, and snow can block the intake, exhaust, or cooling louvers a unit needs to run safely. None of this stops a generator from working. It just means a unit that ran fine in October needs a quick check before it has to run in January.
The North Shore's coldest month is usually January. National Weather Service data for Chicago show an average January high of 31.6 degrees, an average low of 18.8 degrees, and an average of 11.3 inches of snow for the month, based on the 1991 to 2020 climate normals. Cold like that changes how an engine, a battery, and an exhaust system all behave, which is exactly why generator makers build a separate cold weather option into their lineups. A true polar vortex pushes those same conditions to their extreme, which is why we break down what a polar vortex actually does to the Chicago grid, including whether a standby unit still starts at 20 below zero, in its own guide.
Do You Need a Cold Weather Kit
Quick answer: most manufacturers recommend a cold weather kit anywhere winter temperatures fall below 32 degrees, which covers the entire North Shore. The kit adds heating elements that keep the oil, battery, and breather tube warm enough for the engine to start on the first try, even after a night well below zero.
| Cold Weather Kit Part | What It Does |
|---|---|
| Battery warmer | Keeps the battery warm enough to hold a full charge and deliver strong cranking power |
| Oil heater or warmer wrap | Keeps engine oil warm so it flows freely at startup instead of running thick and slow |
| Breather tube heater | Stops condensation inside the breather tube from freezing and blocking airflow |
| Regulator heater | Keeps the fuel regulator from icing up on liquid propane systems |
If your unit is liquid cooled and the manufacturer specifies a cold weather kit, the kit setup often calls for switching to full synthetic 5W-30 oil, which stays thinner in the cold and reduces strain on the engine during a cold start, according to generator dealer guidance on cold weather accessories. Ask your installer whether your specific model already has a kit built in or if it needs to be added, since some units ship without one by default. Generac and Briggs & Stratton both offer cold weather options, though the exact parts and oil specs vary by model. See our Generac vs. Briggs & Stratton comparison if you are still deciding between brands.
Keep the Clearance Zone Free of Snow and Ice
Quick answer: under NFPA 37, the national fire code for standby generators, a listed unit can sit as close as 18 inches from the house and needs at least 5 feet of open space from any window, door, or vent. Snow and ice do not change the code, but a drift piled against the exhaust or intake can block airflow and create a carbon monoxide risk, so the clearance zone has to stay open all winter, not just at install.
After every snowfall of a few inches or more, walk out and clear snow away from all sides of the unit, especially the exhaust outlet and the air intake louvers. A generator buried in a drift can still try to start during its weekly self test or a real outage, and a blocked exhaust turns a safety feature into a hazard fast. For the full breakdown of clearance rules and what your village inspector checks at installation, see our guide to generator permits in Illinois.
Ice is the other problem. A layer of ice on the enclosure roof or louvers can trap moisture against the housing and freeze moving parts. Do not chip at ice with a shovel or hard tool near the cabinet, since it is easy to crack the housing or damage a component underneath. A soft brush or a gloved hand clears loose snow without that risk.
Not Sure Your Generator Is Ready for This Winter?
A licensed and insured electrician can inspect your unit, check the battery, and confirm your cold weather kit is doing its job before the first storm hits.
Get a Free EstimateBattery Care Keeps the Whole System Alive
Quick answer: cold weather cuts a battery's starting power more than almost anything else that can go wrong with a standby generator. Keeping the battery fully charged, clean, and tested before winter is the single best thing an owner can do to avoid a no start call in January.
Most standby generators use an AGM, or absorbed glass mat, battery, which holds its charge longer than an older lead acid battery and does not need water added. AGM batteries lose starting power fast once they sit at a partial charge in freezing weather, and a battery that is only half charged can freeze and fail for good on a hard cold night, according to AGM battery manufacturer guidance. Test the battery with a load tester before the season starts, and clean any corrosion off the terminals so the connection stays solid when the generator needs full power to crank.
A cold weather kit's battery warmer helps here too, since it keeps the battery close to room temperature no matter what the thermometer outside says.
Your Weekly Self Test Schedule
Quick answer: most standby generators run a short self test once a week, usually for about 12 minutes, on a day and time your installer sets during setup. Winter is when that test matters most, since it is the only regular check that the engine, battery, and transfer switch are all still working before a real outage hits.
If your generator normally runs its self test on, say, a Wednesday morning, do not skip a look outside that day once winter sets in. Confirm the exhaust and intake are clear of snow before the test runs, and listen for anything that sounds different than usual, like a slower crank or a rougher start. Some owners move the test to a midday slot in winter so a slow, cold start is easier to notice and address quickly. If the self test fails to run or throws an error code, do not wait for the next one. A generator that cannot complete a 12 minute test on a calm day will not carry your house through a multi day storm.
A Simple Pre Winter Maintenance Checklist
Quick answer: most of what a standby generator needs before winter takes less than an hour and does not require a technician. Work through this list once in the fall, then do a quick walk around after every heavy snowfall.
- Confirm the cold weather kit is installed and working if your model requires one below freezing.
- Switch to synthetic 5W-30 oil if your manufacturer calls for it in cold weather.
- Test the battery and clean the terminals before the first hard freeze.
- Clear snow and ice from the enclosure, exhaust outlet, and air intake after every storm.
- Check that the weekly self test is still running on schedule and sounds normal.
- Keep at least 3 feet of open space around the unit, more if your village or manual requires it.
- Schedule an annual service visit before winter if your unit has not been serviced in the past year.
When to Call a Professional
Quick answer: some winter problems are a quick homeowner fix, like brushing off snow or checking a battery terminal. Others, like a failed self test, an error code, or a generator that will not crank at all, need a trained technician before the next outage arrives.
If your generator throws an error code, fails its self test twice in a row, or sounds noticeably different when it starts, do not wait until you need it in an emergency to find out something is wrong. See our generator troubleshooting guide for what the most common fault codes mean before you call for service, or our maintenance cost guide for what a routine professional visit should cost and cover. A trained technician can diagnose the issue and get it fixed before the next storm, instead of after the power is already out. Our licensed and insured electrician partner handles both routine annual generator maintenance and generator repair across the North Shore, including Northbrook, Wilmette, and Highland Park.
Frequently Asked Questions
Do I really need a cold weather kit in Illinois?
Most manufacturers recommend a cold weather kit anywhere winter lows fall below 32 degrees, which covers the entire North Shore. Without one, cold oil and a cold battery can keep the engine from starting on the first try during a January outage.
What kind of oil should my generator use in winter?
Many manufacturers call for full synthetic 5W-30 oil once a cold weather kit is installed, since it stays thinner in freezing temperatures than standard oil and puts less strain on the engine at startup. Check your owner's manual for the exact spec your model needs.
How close can snow get to my generator?
Snow needs to stay clear of the exhaust outlet and air intake at all times. The unit's normal clearance rules, at least 18 inches from the house and 5 feet from any window, door, or vent under NFPA 37, still apply in winter, so clear the area by hand or with a soft brush after every snowfall.
Can cold weather damage my generator's battery?
Yes. A battery that sits at a partial charge in freezing temperatures can freeze internally and fail for good. Keeping the battery fully charged, clean, and tested before winter is the best way to prevent that.
How often should my generator run its self test in winter?
The standard schedule is once a week for about 12 minutes, and that does not change for winter. What changes is how closely you should check on it, since a slow or rough start in cold weather is an early warning sign worth acting on.
Should I shovel snow off my generator myself?
Light snow can be brushed away by hand or with a soft broom. Avoid chipping at ice with a shovel or hard tool near the cabinet, since it is easy to crack the housing or damage a component underneath.
Winter is the season a standby generator earns its keep, and a little prep in the fall is what makes sure it starts when a storm actually knocks out the power. If you are not sure whether your unit already has a cold weather kit, or if it is due for its annual service before the season starts, request a free estimate and a licensed and insured electrician will take a look before the next cold snap.