GBA Logo horizontal Facebook LinkedIn Email Pinterest Twitter Instagram YouTube Icon Navigation Search Icon Main Search Icon Video Play Icon Plus Icon Minus Icon Picture icon Hamburger Icon Close Icon Sorted

Community and Q&A

Outdoor temperature reports, Thursday January 31

Martin Holladay | Posted in General Questions on

Vermont is warm this morning compared to much of the country. My thermometer reads -15°F.

GBA readers are invited to share their temperature readings. (And readers who heat with minisplits are invited to let us know whether their minisplit is keeping up…)

GBA Prime

Join the leading community of building science experts

Become a GBA Prime member and get instant access to the latest developments in green building, research, and reports from the field.


  1. Expert Member
    Dana Dorsett | | #1

    I's a balmy -5F in my Worcester MA neighborhood. With no wind even the short-haired dog wasn't too miserable on her morning walk.

  2. JeremyArch | | #2

    Not to bad in Southeastern Ontario at -4F, winds feeling like -17F. Two Fujitsu minisplit keeping the house at a comfortable 72-68F (depending on the room).

  3. Expert Member
    Peter Engle | | #3

    It's a balmy +4F in sunny coastal NJ. It's never gone below zero here in the last 20 years. My short-haired dog generally wears a coat when it's below 20 or so. Yes, she's spoiled.

    I was going to include a photo, but I got blocked.

  4. ZenHomes | | #4

    Dropped to -3F in Cincinnati. Sanden CO2 HPWH humming away and making hot water as expected, no frost on evaporator coils even.

  5. this_page_left_blank | | #5

    It's a balmy -25C [-13°F] in London, Ontario, although with periods of sub -40 [-40°F] wind chill.

  6. Expert Member
    BILL WICHERS | | #6

    About -16F this morning. No wind though (yet). All the schools, and even many universities are closed today due to the wind chill warning.

    The gas co is asking everyone in most of lower MI to lower their thermostat through noon Friday. There was a failure in a compressor station yesterday so they’re concerned with low pressure during this time of very high demand due to low temperatures.


  7. natesc | | #7

    In the southern tier of upstate NY we bottomed out around -12 or -13F last night. Pretty common to hit that a couple times a winter. Sun's shining and no wind, these are actually some of the most beautiful days of winter and prefer this to 20F cloudy and windy.

    When we're home we just run the woodstove at this time of year, but I have no doubt that the Mitsubishi FH18 1.5 ton minisplit would have had no problem keeping the house at 68 or 70. This past November was pretty atrocious, we had a -8F night and the minisplit kept the house to temp. We are about 1450 sq/ft, R20 slab, R23+17 walls, R60 attic.

  8. mikecellini_io | | #8

    -13 in Normal, IL right now. This is an unusually cold stretch (hit -20 the night before) for this area and I have an old leaky house so my gas boiler isn't even keeping up (thermostat reading 65 while set at 69).

    Biggest problems are some dropped soffits in the kitchen that need to be sealed on the attic side, including one that is adjacent to an exterior wall with interior surfaces reading as low as 55 right now. The AC ducts in the attic certainly aren't helping, even with the dampers closed.

  9. markgimmeshelter | | #9

    -28F this morning here in central Wisconsin blue sky and sunshine

  10. user-756436 | | #10

    So far, your temperature is the number to beat!

    The photo below, taken this morning, shows my firewood pile. (Fortunately, this is the firewood I intend to burn during the winter of 2019-2020 -- so I don't have to wade through 3 feet of snow to get a few pieces of wood for my stove...)

  11. STEPHEN SHEEHY | | #11

    4° F here in Whitefield ME this morning. Minisplits keeping us warm, even with a five hour power outage late last night.

  12. user-723121 | | #12

    Looks like -23 F was the low at the Minneapolis airport, Blaine, a suburb had -26. The energy upgrade I did to our 1978 house in 2006 has really paid off. I air sealed the attic, added another 24" of blown insulation, put 1 1/2" Thermax on the inside of the basement walls and installed a 95% 2 stage Lennox with ECM motor. House is very comfortable on these very cold days, tomorrow I read gas meters.

    I am amazed at how many homes in the Twin Cities metro are still using 80% or thereabout efficient furnaces, and replacing with the same.

  13. kurtgranroth | | #13

    I may have to compromise on any passive home ideals here in Phoenix AZ due to the hot summers but the tradeoff is days like today. It's 50F as I write this with a forecasted high of 77F!

    So yeah, heating is not an issue. My heat pump is on for 45-min or so at 5am every morning just to kick start the day and then that's it.

  14. Expert Member
    Peter Yost | | #14

    -1 F at 6:30 am in Brattleboro VT this morning. My 1.3 mile walk to work was pleasant because it was calm; no wind. When it gets this cold I cycle our basement HRV (our radon mitigation system) off and on and we trade a bit of radon risk for energy efficiency/basement air thermal comfort...

    Our Weil McLain boiler, while not great as 87% AFUE and 150k Btu sizing (ok, 15 years ago I lost on sizing with our plumbing and heating guy at the time, long since been replaced by Al Jeffers & Son, a high performance contractor).


  15. Chris_Duncan | | #15

    We've been into the low teens at night in the mountains East of Reno. But then the sun comes out and it's intense at this altitude. The Home Depot oil filled radiant heater is on 24-7 in the camper on site but the electric bill hasn't been too bad.

  16. OpusC | | #16

    -1 F on Thursday here in New Milford, CT, and all three of the head units from my Mitsubishi minisplit system were putting out air temperatures of over 100 degrees. I’ve got a 30,000 BTU outdoor unit, so on these super cold days I need to run my 50,000 BTU pellet stove to pick up the slack. The house is about 2,000 sq.ft., and the minisplits are all I need when temperatures are in the 20s and above.

    1. GBA Editor
      Martin Holladay | | #17

      So your 30,000 Btu/h minisplit system won't keep your house warm when the outdoor temperature is, say, 15 degrees F ?

      1. Expert Member
        Dana Dorsett | | #18

        The MXZ-3C30NAHZ is good for the nominal/rated 28,600 BTU/hr all the way down to +5F before it starts to fall off.

        A heat load of 28,600 BTU/hr @ +20F would be on the high side for a tight 2x4 framed 2000' house with an insulated foundation, but about right if it's over an uninsulated basement. If that's what's going on, insulating the basement may be enough improvement that the ductless would keep up at +10F or so.

        If it's a typical 2x6 framed house with an insulated basement it should be keeping up even at 0F at typical wall and window U-factors, but not all houses are "typical". (Are any?)

      2. OpusC | | #20

        Martin, my minisplits keep it tolerable for me and my family down into the teens, but if we have guests we try to make the place a little warmer with the pellet stove (we like it a bit cool). My house is balloon-framed 2x4 with blown-in fiberglass (and an uninsulated basement, as Dana guessed in his reply). I still have some airsealing and insulating to do in an unfinished portion of my attic, I know that the seams aren’t taped in the drywall behind my kitchen cabinets, and there are probably a few other places I could make improvements. Plus there is no sheathing under my clapboards, so cold air blows through the joist bays in parts of my house on cold and windy nights. I imagine that the minisplits would do just fine if I dealt with most of those issues.

        1. GBA Editor
          Martin Holladay | | #22

          Thanks for the details. Makes sense.

  17. user-4053553 | | #19

    This morning was -25C (-13F).
    Doing better now at -13C (9F) and its supposed to warm up starting tomorrow

  18. ElectricHoosier | | #21

    -1F around 9 AM Wednesday morning in Evansville, IN. Clear in the morning after a cloudy night with 1 inch snowfall. NW winds around 15 MPH.

    The 18 years old, 2.5 tons Carrier split air source heat pump ran non stop on Wednesday from 4:45 AM until 9:55 PM, save for one 5 minute break and one 10 minute break when it actually reached the daytime setpoints (66F - 68F). During most of the sunny day, it remained about 1F below the setpoints. It was never able to catch up from our overnight setpoint of 64F. Based on this experience and looking at the logged data on the Carrier COR website, I believe our balance point is 5F -7F. I thought the BP was 0F, but I came to that conclusion just by looking at AUX on old thermostat that didn't record data. This time I turned off aux to test the capacity and the result is included as .pdf file. Also, I had to manually turn off aux in COR thermostat because its logic is to use strip heat at any temp. below 15F (location/zip code dependent?), which is a waste of energy as heat pump COP is >1 down to shut off (-3F?). Temps. below BP are pretty rare here, especially during the day, and the unit does keep up except for the rare polar vortex! New metal roof probably didn't help with heat loss on clear day, but attic does have R70. Still need to insulate over half of basement walls behind drywall and other small insulation details to get to pretty good 1982 2,160 sf house.

    Edit- Carrier claims -30F for shut off temperature of our heat pump compressor! I calculate (from manufacturer data table/interpolation) app. 13.4 MBtuh generated by our old heat pump running non stop on January 30th, 2019 with an average daytime temp. of 5F. COP of 1.6 at -1F (estimated from table).

  19. Northernbuilt | | #23

    Saw this posting a little late, we had -34F on Wednesday and -36F on Thursday morning here in Northern Minnesota. Big warm-up today, 0F right now.
    The local rural electric cooperative was utilizing the electric load management program, controlled electric heat was turned off in which time the back-up system is supposed to kick in. Apparently at these temperatures the relay used in the radio receiver to control the heat can stick. After the load control was stopped, many peoples electric heat did not come back on.

    1. GBA Editor
      Martin Holladay | | #24

      That's cold.

    2. Krohner | | #37

      Nice, I am glad someone got a pic of those temp readings. I can second those temps in Northern MN. I was quite surprised the mini split we install for AC and supplemental heating in the shoulder seasons was still putting out heat when the air temp was -35 deg F (not the wind chill that was -50ish from local reports). I had been expecting it to shut off at -20 deg F.

  20. irene3 | | #25

    It's only gotten barely below freezing here in Seattle, but I should get some data over the next week or so. Today (right around freezing and snowing lightly) I've had to shove the thermostat up a couple of times to get the temperature up to where I want it to be (e.g., it was set at 67 but wouldn't get higher than 65 unless I put it up to 69 -- doesn't that defeat the purpose of an automatic thermostat?). But we've been comfortable enough, and the thermostat thing has happened before on much milder days. (N.B. We don't have heat strips installed, so I haven't worried about accidentally engaging them when not needed.)

    1. Expert Member
      BILL WICHERS | | #26

      If your system can’t reach the setpoint you’ve programmed for your thermostat, increasing that setpoint won’t do anything to make it warmer. Your system is, as I like to say, “losing the battle” which is a way of saying that the system running at 100% isn’t able to provide enough energy to overcome the losses of your house so it can’t even maintain the temperature, so raising the temperature is not possible. The thermostat only tells the system when to shut off and stop producing heat.

      If your current system isn’t able to maintain your desired setpoint with the current outdoor conditions (outdoor temperature and wind speed), then your house either isn’t insulated/sealed well enough or your heating system is undersized or not performing properly.


      1. GBA Editor
        Martin Holladay | | #29

        I disagree with your analysis. If we're talking about a ductless minisplit, sometimes the thermostat isn't very accurate. The unit may have plenty of available capacity -- it just thinks it has reached the set point when it hasn't.

        If that's the case, the homeowner who wants 70 F but is frustrated by a minisplit that only brings the indoor temperature to 67 F can sometimes set the thermostat to 74 F -- and may discover that this change results in 70 F indoor air.

        1. Expert Member
          BILL WICHERS | | #30

          Martin, is your thinking in this case that the minisplit is modulating down as it approaches the set point, thus lowering the air temperature it produces as it “tapers off”, but never quite making it to the setpoint? Or are you thinking that the thermostat is not accurate in terms of comparing it to something else, maybe another thermostat internal to the minisplit?

          My thinking was that if the unit is running full out, and it can’t make it to the setpoint, then changing the thermostat setpoint won’t change the fact that the unit is already running at max capacity.


          1. Expert Member
            Dana Dorsett | | #31

            Most mini-splits sense the room temperature by the temperature of the incoming air at the head. For lots of reasons a high-mount wall coil can have incoming air substantially warmer than the average room temperature. It's common to see offsets of 5-10F during the weather extremes.

            Wired or wireless wall-remotes for mini-splits programmed to use the temperature sensor inside the remote (much as a thermostat would) can remove those effects. But like any wall thermostat the placement of the wall remote may make it's temperature different from the average room temperature.

          2. Expert Member
            BILL WICHERS | | #38

            Dana and Martin: thanks for the info about the mini splits. I’ve never used them for heat, only cooling, so I have limited practical expierience with them. I thought there might be some peculiarities to their modulation, looks like there is.


    2. canada_deck | | #28

      Are you reading the temperature off of the thermostat or from somewhere else in the house?

      1. irene3 | | #33

        On the thermostat itself. The thermometer elsewhere reads similarly. Martin's description is right, though I have no idea why the system may "think" it's reached the set point when the thermostat is right there telling it that it hasn't. Our system is ducted, so it's not the situation Dana describes where it's going by the incoming air at the head.

        1. Expert Member
          Dana Dorsett | | #35

          Ducted Fujitsu mini-splits still sense the room air at the mini-duct cassette, unless specifically programmed to use the sensor in the wall remote.

          Most vendors' large air handler heat pumps don't have an option for running off of intake air temperature, and only work from exterior thermostats.

          1. irene3 | | #36

            It's not a mini-ducted system. It has an air handler connected to the old forced-air furnace ducts.

  21. AndyKosick | | #27

    Late to the post, but it was -12F Thursday morning in mid Michigan and my Mitsubishi MXZ-2c20NAHZ was not keeping up. About 62F in the morning, for 68 set point. Problem is not it's ability to make heat but it was defrosting for about 10 to 15 minutes and then running for 30 or so, and then defrost again. That's a 30% capacity hit and in three days of sub zero temps I don't think a thimble full of water came off the coils, so this was a bit frustrating. I'm having the installer out to check it this week and if that doesn't yield results I may post something in Q&A with more details. Anyone else ever have a similar experience?

    1. joshdurston | | #32

      I wonder how smart it is about defrost? Is it a set ratio depending on runtime vs outdoor temp, or is it smart enough to detect lower performance from the outdoor coil?

      This kind of equipment is can do some amazing things, but the opacity of the some of the documentation is frustrating when it comes to sequences of operation, and operational algorithms.

  22. irene3 | | #34

    Well, this morning it's not getting above 58 (25 outside), so we have a call in to the installer.

Log in or create an account to post an answer.


Recent Questions and Replies

  • |
  • |
  • |
  • |