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Official data, decoded

Reefer heat and freeze days: how often the air is hot or freezing on your lanes

NOAA climate normals count the days in each month with a high of 90 or 100 degrees and the days with a low at or below 32 or 20 degrees. For 44 freight cities they show which months load a reefer unit hardest and which ones put a dry van or produce load at risk of freezing. A small calculator turns those days into fuel dollars with your own consumption figure.

Climate normalsNOAA NCEI U.S. Climate Normals 1991-2020, monthly, 44 stationsData as of the 1991-2020 normals period (published by NOAA in 2021)Retrieved Oct 10, 2026, 05:30 UTCretrieved Oct 10, 2026

Read this first

Normals are 30-year averages of air temperature at one airport station per city. They are not a forecast, not pavement or trailer temperature, and not a statement about any lane between the cities. The extra-fuel figure uses your own gallons per hour; we publish none.

A typical July in Phoenix, AZ has 30.8 days at 90 F or more; a typical January in Fargo, ND has 30.8 nights at 32 F or colder. Weather that loads a reefer unit and weather that freezes freight sit in different months in different cities.

Chart and calculator

Pick a city, a month and the measure. The calculator turns the hot-day count into fuel dollars from your own figures.

Days with a high of 90 F or more, 1991-2020 normals, Dallas-Fort Worth, TX

010203040JanFebMarAprMayJunJulAugSepOctNovDec

Bars: average days per month. Orange: the month you pick below. Station: DALLAS FT WORTH AP, TX US.

Pick a place and month

Average in that month
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Share of days
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The first three values are Example data. Gallons per hour is your own measured figure; the page has no reefer fuel data.

Days your reefer trailer spends in or near that place.
Hours the unit runs on a hot day.
Your own figure, from your fuel logs. Not provided here.
Your own price, or the EIA average.

Expected extra fuel on hot days

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Expected days with a high of 90 F or more in your trip
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Enter the trip.

Formula: expected hot days = days on the road x (average hot days in the month / days in the month). Cost = expected hot days x run hours x extra gallons per hour x diesel price, rounded once to the cent. February is counted as 28 days. Nothing you type leaves this page.

Days with a high of 90 F or more, by month

Average days per month, 1991-2020. Darker orange means more days.

Average days per month with a high of 90 F or more, 1991-2020 normals
Station cityJanFebMarAprMayJunJulAugSepOctNovDec
Albuquerque, NM0.00.00.00.02.919.022.316.53.70.00.00.0
Atlanta, GA0.00.00.00.02.09.916.413.74.90.30.00.0
Baltimore, MD0.00.00.00.42.16.713.48.22.80.20.00.0
Billings, MT0.00.00.00.00.42.913.712.22.80.10.00.0
Birmingham, AL0.00.00.00.12.912.920.419.09.20.60.00.0
Boise, ID0.00.00.00.11.46.622.119.54.80.30.00.0
Boston, MA0.00.00.00.10.62.56.33.80.80.00.00.0
Buffalo, NY0.00.00.00.00.20.71.50.70.30.00.00.0
Charlotte, NC0.00.00.00.12.110.318.013.55.00.30.00.0
Chicago, IL0.00.00.00.00.84.16.53.71.60.00.00.0
Cleveland, OH0.00.00.00.00.42.84.73.11.40.00.00.0
Columbus, OH0.00.00.00.00.74.57.55.52.30.20.00.0
Dallas-Fort Worth, TX0.00.10.10.76.922.328.727.616.23.60.10.0
Denver, CO0.00.00.00.00.88.618.813.84.20.00.00.0
Detroit, MI0.00.00.00.00.53.25.32.71.20.00.00.0
El Paso, TX0.00.00.12.415.927.227.525.615.32.70.00.0
Fargo, ND0.00.00.00.10.92.13.93.11.10.10.00.0
Fresno, CA0.00.00.12.08.820.229.528.819.93.80.00.0
Houston, TX0.00.00.10.99.523.127.327.118.35.00.00.0
Indianapolis, IN0.00.00.00.00.33.47.45.92.80.10.00.0
Jacksonville, FL0.00.00.21.38.416.223.620.39.01.10.00.0
Kansas City, MO0.00.00.00.20.87.113.111.63.30.20.00.0
Laredo, TX0.31.98.015.323.829.430.330.724.017.52.80.4
Las Vegas, NV0.00.00.33.515.926.930.630.424.15.50.00.0
Little Rock, AR0.00.00.00.13.515.923.422.010.70.80.00.0
Los Angeles, CA0.00.00.00.30.30.10.10.50.91.80.70.0
Louisville, KY0.00.00.00.01.28.614.312.65.50.40.00.0
Memphis, TN0.00.00.00.13.115.522.120.210.20.90.00.0
Miami, FL0.00.00.82.16.015.223.824.714.84.00.10.0
Minneapolis, MN0.00.00.00.10.82.95.42.41.00.00.00.0
Nashville, TN0.00.00.00.12.010.818.215.96.80.40.00.0
New Orleans, LA0.00.00.00.25.918.422.923.012.82.00.00.0
Newark, NJ0.00.00.00.31.95.411.37.42.00.00.00.0
Oklahoma City, OK0.00.00.20.53.013.824.222.18.80.90.00.0
Omaha, NE0.00.00.00.31.77.311.77.93.90.30.00.0
Philadelphia, PA0.00.00.00.21.75.812.57.51.90.00.00.0
Phoenix, AZ0.00.02.110.223.629.430.830.728.416.81.40.0
Portland, OR0.00.00.00.00.41.85.05.32.10.00.00.0
Raleigh, NC0.00.00.00.32.812.118.613.84.50.40.00.0
Sacramento, CA0.00.00.00.95.312.320.619.713.83.10.00.0
Salt Lake City, UT0.00.00.00.01.310.324.321.45.00.00.00.0
Savannah, GA0.00.00.11.17.116.524.620.69.60.90.00.0
Seattle, WA0.00.00.00.00.00.61.81.20.20.00.00.0
St. Louis, MO0.00.00.00.31.910.615.913.05.00.40.00.0

Source: NOAA NCEI, variable MLY-TMAX-AVGNDS-GRTH090. Station file for each city is listed on the NOAA source page; the station is the nearest airport-class station within 45 km of the city centre.

Days with a low of 32 F or less, by month

Average days per month, 1991-2020. Darker blue means more freezing nights.

Average days per month with a low of 32 F or less, 1991-2020 normals
Station cityJanFebMarAprMayJunJulAugSepOctNovDec
Albuquerque, NM26.118.28.21.60.10.00.00.00.01.211.725.7
Atlanta, GA12.87.73.00.20.00.00.00.00.00.12.99.1
Baltimore, MD24.021.013.92.40.00.00.00.00.01.010.420.6
Billings, MT27.324.421.110.61.70.00.00.00.48.020.527.5
Birmingham, AL14.99.84.20.60.00.00.00.00.00.15.412.0
Boise, ID25.520.111.25.20.80.00.00.00.23.716.325.2
Boston, MA24.821.716.22.10.00.00.00.00.00.26.819.8
Buffalo, NY27.125.322.79.30.20.00.00.00.02.013.124.0
Charlotte, NC16.612.06.30.70.00.00.00.00.01.07.414.4
Chicago, IL28.124.419.96.00.20.00.00.00.12.714.525.4
Cleveland, OH25.823.520.36.30.20.00.00.00.01.011.622.1
Columbus, OH24.922.116.74.20.20.00.00.00.01.612.021.5
Dallas-Fort Worth, TX10.66.21.90.00.00.00.00.00.00.12.38.1
Denver, CO29.026.123.213.22.90.00.00.00.79.222.729.2
Detroit, MI27.225.121.06.20.30.00.00.00.01.913.724.2
El Paso, TX14.56.51.90.00.00.00.00.00.00.44.714.0
Fargo, ND30.827.326.715.62.80.00.00.00.912.025.530.8
Fresno, CA4.20.90.00.00.00.00.00.00.00.00.74.9
Houston, TX4.11.70.70.00.00.00.00.00.00.00.72.9
Indianapolis, IN25.722.315.83.70.20.00.00.00.02.113.022.6
Jacksonville, FL6.22.71.00.00.00.00.00.00.00.00.83.6
Kansas City, MO27.322.013.93.40.00.00.00.00.02.313.324.6
Laredo, TX1.30.20.00.00.00.00.00.00.00.00.10.5
Las Vegas, NV3.31.10.10.00.00.00.00.00.00.00.74.6
Little Rock, AR16.510.93.80.20.00.00.00.00.00.15.113.4
Los Angeles, CA0.00.00.00.00.00.00.00.00.00.00.00.0
Louisville, KY21.316.79.51.20.00.00.00.00.00.58.116.8
Memphis, TN14.910.03.50.20.00.00.00.00.00.14.311.5
Miami, FL0.00.00.00.00.00.00.00.00.00.00.00.0
Minneapolis, MN30.526.823.89.00.50.00.00.00.25.820.929.7
Nashville, TN18.814.27.40.90.00.00.00.00.00.78.415.8
New Orleans, LA2.90.90.20.00.00.00.00.00.00.00.41.0
Newark, NJ22.620.012.41.20.00.00.00.00.00.16.017.5
Oklahoma City, OK21.815.16.41.30.00.00.00.00.00.87.918.8
Omaha, NE29.725.619.96.30.30.00.00.00.14.419.129.0
Philadelphia, PA22.519.611.80.80.00.00.00.00.00.15.417.2
Phoenix, AZ0.40.10.00.00.00.00.00.00.00.00.00.1
Portland, OR8.77.22.60.30.00.00.00.00.00.44.18.4
Raleigh, NC18.013.87.81.10.00.00.00.00.00.77.815.4
Sacramento, CA5.01.90.20.00.00.00.00.00.00.01.66.7
Salt Lake City, UT27.421.312.04.00.20.00.00.00.02.717.326.8
Savannah, GA8.64.21.50.10.00.00.00.00.00.01.45.7
Seattle, WA7.05.81.90.10.00.00.00.00.00.23.07.2
St. Louis, MO24.118.910.31.40.00.00.00.00.00.69.120.4

Source: NOAA NCEI, variable MLY-TMIN-AVGNDS-LSTH032. Days at 20 F or less (LSTH020) are in the chart picker above.

What it means for your fleet

  • Budget the hot months by city. A lane through a station with 15 or more hot days in July loads the unit more than one with 2. Use your own fuel logs for the gallons.
  • Plan the cold months for freight, not only the truck. Nights at 32 F or colder matter to produce, liquids and anything that must not freeze. Check the requirement on the bill of lading.
  • Do not price from normals alone. The 1991-2020 average can hide a hot or cold year. Use it to set a seasonal buffer and review it with real weather.
  • Note what the station is. It is an airport, so mountain passes, deserts and coasts on your route can differ.
  • Keep records. Dated weather and fuel logs help in a claim or a rate talk.

Questions

What do "days at 90 F or more" mean?

NOAA's 1991 to 2020 monthly normals list, for each station and month, the average number of days when the highest air temperature was at or above 90 degrees Fahrenheit. A value of 16.4 for July means a typical July has about 16 such days.

Is this a forecast?

No. Normals are 30-year averages, so a single year can run well above or below. They tell you what is usual for the month, not what next week will bring.

Why one station per city?

Each city uses the nearest airport-class weather station within 45 km of the city centre. Airport stations measure air temperature in a shaded screen, not pavement, trailer or cargo temperature. A route through the mountains or a desert can differ a lot from the city.

Where does the extra fuel number come from?

From figures you type: run hours, extra gallons per hour and a price. The page gives no reefer fuel rate. An example value is pre-filled and labelled so you can see the arithmetic.

Which stations are covered?

44 metro areas with a usable station and all twelve normals. Cities where the nearest airport station lacked a complete record are not listed.

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