Why do my Moncton windows drip condensation all through January?

That dripping condensation is almost certainly telling you that warm, humid indoor air is hitting cold glass — and in Moncton's January climate, that's a very common battle. When outdoor temps drop to -15°C or colder (which happens regularly inland from the coast), even a reasonably good window will struggle if your indoor humidity is too high or your window's thermal performance is marginal.

Here's what's actually happening: warm air inside your home holds moisture. When that air contacts the cold surface of your window glass, it cools below its dew point and the moisture drops out as condensation. The colder the glass, the worse it gets — and January in Moncton regularly delivers the conditions to make this happen nightly.

The first thing to check is your indoor relative humidity. For Moncton's January temperatures, you want indoor humidity between 25–35%. Above 40% and you'll see condensation on almost any window. A basic digital hygrometer costs $15–$25 at any hardware store and tells you exactly where you stand. Common humidity culprits in Moncton homes include: poorly vented bathroom fans (check that the duct actually exits the building, not just into the attic), dryer vents that have come loose, cooking without range hood ventilation, and even a large number of houseplants.

Where the condensation appears matters a lot. If it's forming on the interior glass surface, that's a humidity/ventilation issue you can likely manage yourself. If it's forming between the panes of a double or triple-pane window, the sealed unit has failed — the argon or air seal is broken and moisture has gotten in. That requires replacing the glass unit (not necessarily the whole frame), typically $150–$350 per window for a standard size in the Moncton market.

Moncton's housing stock is worth considering here. If you're in a post-war bungalow or a 1970s–1990s split-level (very common in older Moncton and Riverview), your windows may be original or near-original — single-pane or early double-pane units with aluminum frames that conduct cold aggressively. Those frames will frost and drip in January no matter what you do with humidity. Replacement is the real fix.

Modern window performance is rated by ER (Energy Rating) and U-factor. For New Brunswick's climate zone, look for windows with a U-factor of 1.4 or lower (lower is better) and an ER of 34 or higher. Under the NBC 2020 Tier 2 requirements (mandatory for new construction as of May 1, 2025), window performance standards have tightened — worth keeping in mind if you're replacing windows, as better-performing units are now the baseline expectation.

NB Power offers rebates through their Total Home Energy Savings Program for qualifying window upgrades — worth checking nbpower.com before you purchase, as rebates can offset a meaningful portion of the cost. Window replacement in Moncton typically runs $400–$900 per window installed for standard residential sizes, mid-range product. Premium triple-pane units run $900–$1,500+ per window.

A practical first step: grab a hygrometer this week and measure your humidity. If it's above 40%, run your bathroom fans longer after showers (20–30 minutes minimum), check that all exhaust fans actually vent outside, and consider a heat recovery ventilator (HRV) if your home feels stuffy. If humidity is already in the right range and you're still getting heavy condensation, the windows themselves are the problem — and that's a conversation worth having with a window contractor in our directory.