Bar chart of furnace problems in cold weather: average Google Trends heating-repair search interest by the week’s lowest temperature at Dulles, DC metro and Virginia, 2021 to 2026

How Cold Does It Have to Get Before Heating-Repair Searches Rise? We Compared 5 Years of Search and Weather Data

It’s the first frosty morning of the season. The furnace that sat quiet since March tries to start, and you wonder whether everyone in Northern Virginia is having the same trouble this week.

This isn’t a lab test or a computer model of a furnace. It’s a data analysis: we compared Google Trends search-interest data for four heating-repair phrases with NOAA temperature records from Washington Dulles International Airport, week by week, for five heating seasons. Google Trends shows relative interest, not the number of searches, and it says nothing about actual repair calls.

The timing matters right now. In each of the last 10 years, Dulles recorded its first fall low of 32°F or colder between October 21 and November 10, with a typical date around October 30. That’s also the week our data points to.

How we compared searches and weather

Google Trends scores each week from 0 to 100, relative to the busiest week in the chosen place and period. It uses a sample of searches, and phrases with too few searches show as 0. A score of 10 doesn’t mean 10 searches.

For each week we took the coldest daily low at Dulles. Then we checked the correlation between search interest and that low (0 means no relationship, 1 a perfect one), the same check against the previous week’s low, whether weeks that turned colder also saw interest rise, and how interest changed in the first freezing week of each fall compared with the four weeks before.

Results: furnace problems in cold weather in the search data

Every number here is search-interest data about furnace problems in cold weather, not a count of broken furnaces. A positive correlation means colder weeks tended to have higher interest.

Graph 1 groups the 131 October-to-March weeks by how cold it got at Dulles. Interest roughly doubles from weeks with lows in the 30s to weeks that dipped below 15°F. But the steps aren’t smooth: weeks with lows between 15°F and 24°F averaged a little less interest than weeks between 25°F and 31°F. Only five heating-season weeks stayed at 40°F or warmer, so that bar rests on very little data.

Graph 2 zooms in on the first freezing week of each fall in Virginia. In every season, interest that week was higher than the average of the four weeks before it, and it usually eased again the week after. The rises are small, though: 2 to 5 points on a 0–100 scale. In the DC metro the same pattern held in four of five falls. In fall 2024 the DC numbers were too sparse to show anything: the freeze week and the week after both read 0.

Why the search data on furnace problems in cold weather is so noisy

Three things blur the picture.

  • Sparse local data. These phrases don’t get enough searches in one metro area for Trends to report every week. From September through November 2024, 10 of 13 weeks in the DC metro read 0.
  • Season, not just temperature. Interest kept climbing through winter. In March 2025 the DC metro averaged 16.1 even though weekly lows were back in the 20s and 30s, higher than any week from September through November 2024. Searching seems to build over the season, so cold weeks and late-winter weeks are hard to separate.
  • Changes in the data itself. Values from mid-2025 onward run higher across the board, likely a change in how Trends samples or scales. That lifts the 2025 bars in Graph 2 and inflates monthly averages, so we didn’t lean on the monthly pattern.

The phrases also behave differently. In the 5-year Virginia view, “no heat” and “heat not working” peaked in January, while “furnace repair” and “heater repair” peaked in June and July.

What this means for your home

Search data can’t predict furnace problems in cold weather in your own house. What it does show is when heating trouble becomes top of mind across the region: the first freezing week, usually in late October or early November, and the deep cold of January. Here’s how we’d use that:

  • Test the heat before the first freeze. Run the furnace on a mild afternoon in October. A burning-dust smell for the first few minutes is common after a summer off. A smell that doesn’t fade, a burner that clicks but won’t light, or cold air from the vents are worth a call.
  • Change the filter. The Department of Energy notes that a dirty or clogged filter can dramatically reduce airflow, increasing run time and wear on the motor.
  • Expect longer run times on cold days. A furnace that runs longer at 15°F than at 40°F is usually doing its job, because the house loses heat faster. Short, frequent cycling or no heat at all is a different story, and those are the furnace problems in cold weather worth a call.
  • Check the thermostat. Dead batteries or a wrong mode setting can look like a furnace that won’t start. Our thermostat repair page covers the common faults.

If you’d rather have it checked, a $99 heating tune-up before the first cold week catches many of the small faults that turn into furnace problems in cold weather. If the heat is already out, see our furnace repair and heat pump repair pages.

Where these results could differ

  • Other phrases: we analyzed four phrases averaged together. A single phrase, such as “no heat,” may track winter more closely.
  • Other places: colder regions with more searching may show a stronger link. Virginia-wide data was a little stronger than the DC metro alone.
  • Longer history: the original plan called for 10 years. Google Trends only gives weekly data for up to five years, so we used five seasons for the weekly comparison and 10 years only for first freeze dates.
  • Searches aren’t breakdowns: people search about furnace problems in cold weather for many reasons, including curiosity or comparing companies. A rise in interest doesn’t mean more furnaces failed, and this data can’t show that cold weather caused any failure.

Heating safety comes first

The U.S. Consumer Product Safety Commission advises having a professional inspect all fuel-burning heating systems, including furnaces, chimneys, flues and vents, each year. It also says carbon monoxide alarms should be placed on every level of the home and outside sleeping areas, because fuel-burning heaters can produce CO, an odorless, colorless and deadly gas. Test your CO alarms when you turn on the heat for the season, and don’t try to fix gas furnace problems in cold weather by opening up the burner or gas valve yourself.

If you smell gas, Washington Gas says to leave the area, move to a safe location, call 911 and then call its emergency leak line. Don’t light a flame or operate switches on the way out.

Furnace repair in Northern Virginia

Late October and early November, when Dulles sees its first freezing nights, is when many furnaces run for the first time since spring. Woodland handles furnace repair across Prince William, Fairfax, Loudoun and Fauquier counties, plus Arlington and Alexandria. We’re based in Woodbridge, so Woodbridge, Manassas, Dumfries and Lorton are usually same-day calls, and we’re in Fairfax, Centreville, Springfield, Arlington and Alexandria every week. See our furnace repair page or call (703) 335-1009.

Sources and methodology

Methodology: we averaged the four phrases’ weekly Trends scores and matched each Sunday–Saturday week to NOAA daily records at Dulles (weeks with at least five days of data). Correlations are Pearson correlations over the 131 October–March weeks.

Limits: neighboring weeks move together, so the correlations look more certain than they are. Trends values change if the window or phrase list changes. We had no repair-call data, and this analysis can’t show cause and effect.

Check: we recomputed the fall 2024 first-freeze figures for the DC metro by hand from the weekly series and they matched the summary values.

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