--- title: Cold Weather and Propane Tank Pressure | American River Gas url: https://americanrivergas.com/guides/cold-weather-propane-tank-pressure/ business: American River Gas Co., Inc. phone: (530) 888-7438 address: 10290 Ophir Rd, Newcastle, CA 95658 hours: Monday-Friday 8:00 AM-4:30 PM (closed noon-1:00 PM) updated: 2026-10-28 --- Tanks & gauges # Cold weather, tank pressure and frozen regulators Propane pressure in your tank rises and falls with the temperature, and on cold days the tank also turns liquid into vapor more slowly, especially when it is low, so a nearly empty tank in a cold snap is the setup most likely to leave appliances short of gas. Keep the tank above about 30%, keep snow and ice off the regulator and piping, and never try to warm a tank with any heat source. [Call (530) 888-7438](tel:+15308887438)[Open an account](https://americanrivergas.com/open-an-account/) ## Why pressure drops when it gets cold Propane sits in your tank as a liquid with a layer of vapor above it. The vapor pressure depends almost entirely on the temperature of the liquid, not on how many gallons are left. Published tables put propane at roughly 110 to 130 psig at 70 degrees F, depending on the reference and the propane mix, falling to around 70 psig at 40 degrees and around 45 psig at 20 degrees. Propane boils at about minus 44 degrees F, so it keeps producing vapor on any winter day the foothills are likely to see. Pressure alone is rarely the problem here. The bigger issue is how fast the tank can make vapor when the furnace, water heater and fireplace all call for gas at once. ## Vaporization: the part that trips people up Liquid propane pulls heat from the steel shell of the tank as it boils into vapor. The same handbook explains that a container's vaporization rate depends on the temperature of the liquid and the wetted surface, meaning the part of the tank wall in contact with liquid. Colder air or less liquid in the tank both lower the rate. Heavy, steady use also chills the tank from the inside. PERC compares it to a can of spray paint that turns cold in your hand. On a busy winter evening a tank may sweat or frost along the liquid level. That is the cooling effect at work, not a leak, though you should still call if you smell gas or hear hissing. - A fuller tank has more wetted surface, so it keeps up with demand better in cold weather. - A tank that is low in January can struggle to feed a large furnace even though the gauge is not yet at zero. - Adding a big appliance, like a whole-home tankless water heater, raises the demand the tank must meet on its coldest day. ## What freezes a regulator The regulator under your tank dome or on the side of the house reduces tank pressure to the low pressure your appliances use. It has to breathe through a small screened vent. Emerson's regulator inspection bulletin names freezing rain as the most common cause of a blocked vent, and dense snow, ice and runoff from a roof eave can do the same. Water that gets inside a regulator can freeze across the diaphragm so it cannot move. Moisture in the gas itself can also freeze inside a regulator. Two-stage systems, with one regulator at the tank and one at the building, reduce that risk because the pressure drop is split in two. A regulator installed with its vent pointing down, or under a cover or the tank dome, resists freeze-ups. ## Snow and ice: what to do - Brush heavy snow and ice off the regulator, piping and meter with a broom rather than a shovel, so you do not crack a fitting. PERC gives the same advice. - Keep appliance intake and exhaust vents on walls and roofs clear, so exhaust gases can leave the house. - If snow slides off your roof onto the regulator, ask us about a cover or a better location. - In a heavy snow year, mark the tank and regulator with a tall stake so they can be found and kept clear. - Clear a path to the tank and keep the driveway passable so the truck can reach you. Our drivers carry a 120-foot hose, but they still need to get within reach of the fill valve. ## Never warm the tank It is tempting to aim a heater or a torch at a cold tank. Don't. PERC is blunt about it: never keep a propane tank or cylinder warm with an external heat source. Heat can raise the pressure high enough to open the relief valve and release propane. If your appliances are starving for gas in a cold snap, call the office instead. ## How we plan fills around the cold American River Gas fills tanks to about 86% in winter and about 80% in summer. The difference is headroom: propane expands as it warms, and a tank filled on a cold morning needs less space held back than one filled on a hot afternoon. On Keep Full automatic delivery, fills are timed from outdoor temperatures and your past use, so a cold stretch moves your next delivery up. If you order your own deliveries, call when the gauge reads about 30%. Trucks serve each part of the delivery area on a set route day, and ordering at 30% leaves time to reach you, usually within a week, before a cold snap drains the tank. If a tank does run out, do not try to restart appliances yourself. Safety codes and our insurance require a pressure check and leak test after any interruption in service, including running out of gas, and the homeowner must be present. There is an extra charge for that visit. On Keep Full with an account in good standing, there is no charge for the leak test or special trip if you run out, with some restrictions. If you smell gas, leave the building first, then call 911 and us from outside. Questions ## Straight answers ### Does cold weather make my propane gauge read wrong? The gauge reads liquid level, so cold does not change the percentage much, but a needle can stick in the cold. Lift the dome 6 to 8 inches and let it drop to free it, then read again. ### Can propane freeze in my tank? Not at foothill temperatures. Propane boils at about minus 44 degrees F. What can freeze is water in or around the regulator, which blocks its vent or stops its diaphragm. ### Why do my appliances run weak on the coldest nights? A cold, low tank vaporizes propane more slowly. Keeping the tank above about 30% gives it more wetted surface to keep up. If it continues, call us to check the regulator and tank sizing. ### Can I put a heater or blanket on my propane tank? Do not apply any external heat source to a tank or cylinder. Extra heat can raise pressure enough to open the relief valve. Call the office instead. [All questions →](https://americanrivergas.com/faq/)  ·  [Propane guides →](https://americanrivergas.com/guides/) Related ## Keep reading - [Keep Full Automatic Delivery](https://americanrivergas.com/services/keep-full-automatic-delivery/): We track your use and the weather and fill you on schedule. - [Winter prep: driveway access and snow for delivery trucks](https://americanrivergas.com/guides/winter-propane-delivery-access/): Safety & seasons - [Propane regulators explained: what they do and when they are replaced](https://americanrivergas.com/guides/propane-regulators-explained/): Tanks & gauges - [How to read your propane tank gauge](https://americanrivergas.com/guides/how-to-read-a-propane-tank-gauge/): Tanks & gauges Sources: [Emerson Fisher LP-Gas Serviceman's Handbook (LP-10): vapor pressure and vaporization rates](https://www.emerson.com/is/content/emerson/en/final-control/pressure-management/handbooks/lp-10-handbook-en-us-8439918.pdf) · [Emerson Fisher Bulletin LP-32: Inspecting LP-Gas Regulators (February 2023)](https://www.emerson.com/is/content/emerson/en/final-control/flow-controls/documents/d450142t012.pdf) · [Propane Education & Research Council: Safety Guide for Propane Users (PRC-101063D, 2025)](https://cloudinary.propane.com/images/v1777645361/website-media/PRC-101063D-Propane-Safety-Booklet_digital-1_144644b80f7_151323cd231/PRC-101063D-Propane-Safety-Booklet_digital-1_144644b80f7_151323cd231.pdf) · [NIST Chemistry WebBook: propane phase change data](https://webbook.nist.gov/cgi/cbook.cgi?ID=C74986&Mask=4)