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HVAC busy season is summer for cooling and winter for heating, and when each one hits depends on where you are. Here it is for 30 US metro areas, month by month.

From the data

Hottest month on the listPhoenix, AZ in Jul: 945 cooling degree days
Coldest month on the listMinneapolis-St. Paul, MN in Jan: 1,513 heating degree days
Most contractorsNew York, NY: 7,640 plumbing, heating and air-conditioning contractors (2023)

When is HVAC busy season? It depends where you are. Florida runs on cooling from May to October. Texas, Arizona and Nevada peak from June to September, Houston from May. Most of the Northeast and Midwest has two seasons: heating from December to March, and a shorter cooling peak in summer. Seattle, Portland and San Francisco have a heating season only, and Los Angeles and San Diego a short cooling one, July to September.

Warmest metros at the top, coldest at the bottom. Each metro's name opens its card below, with the full table of numbers.

Metro by metro. The heating and cooling months, the month-by-month numbers, and how many contractors work there.

Miami, FL

Cooling: May–OctNo real heating season

2,638 plumbing, heating and air-conditioning contractors (2023) · weather at Miami International Airport

Monthly numbers
MonthHeating degree daysCooling degree days
Jan44156
Feb22182
Mar8260
Apr0352
May0466
Jun0534
Jul0590
Aug0595
Sep0538
Oct0467
Nov3297
Dec26219

Phoenix, AZ

Cooling: Jun–SepNo real heating season

1,737 plumbing, heating and air-conditioning contractors (2023) · weather at Phoenix Sky Harbor International Airport

Monthly numbers
MonthHeating degree daysCooling degree days
Jan2562
Feb15916
Mar65105
Apr14259
May1528
Jun0792
Jul0945
Aug0910
Sep0727
Oct6390
Nov8588
Dec2882

Tampa, FL

Cooling: May–OctNo real heating season

1,429 plumbing, heating and air-conditioning contractors (2023) · weather at Tampa International Airport

Monthly numbers
MonthHeating degree daysCooling degree days
Jan15261
Feb8881
Mar44154
Apr7274
May0448
Jun0538
Jul0583
Aug0589
Sep0532
Oct3388
Nov34178
Dec105102

Orlando, FL

Cooling: May–OctNo real heating season

967 plumbing, heating and air-conditioning contractors (2023) · weather at Orlando International Airport

Monthly numbers
MonthHeating degree daysCooling degree days
Jan18046
Feb10567
Mar54127
Apr10224
May0383
Jun0486
Jul0546
Aug0547
Sep0480
Oct6329
Nov43140
Dec12776

Houston, TX

Cooling: May–SepHeating: Dec–Feb

1,909 plumbing, heating and air-conditioning contractors (2023) · weather at Houston Intercontinental Airport

Monthly numbers
MonthHeating degree daysCooling degree days
Jan36617
Feb23632
Mar12285
Apr31179
May1384
Jun0540
Jul0623
Aug0625
Sep0465
Oct26239
Nov15870
Dec32529

Las Vegas, NV

Cooling: Jun–SepHeating: Dec–Feb

631 plumbing, heating and air-conditioning contractors (2023) · weather at Las Vegas McCarran Airport

Monthly numbers
MonthHeating degree daysCooling degree days
Jan4800
Feb3231
Mar16636
Apr55136
May8390
Jun1679
Jul0876
Aug0828
Sep0560
Oct32200
Nov25016
Dec5190

San Antonio, TX

Cooling: Jun–SepHeating: Dec–Feb

786 plumbing, heating and air-conditioning contractors (2023) · weather at San Antonio International Airport

Monthly numbers
MonthHeating degree daysCooling degree days
Jan4067
Feb26622
Mar13971
Apr35166
May3359
Jun0526
Jul0614
Aug0634
Sep1446
Oct34229
Nov18658
Dec36914

Austin, TX

Cooling: Jun–SepHeating: Dec–Feb

825 plumbing, heating and air-conditioning contractors (2023) · weather at Austin Bergstrom Airport

Monthly numbers
MonthHeating degree daysCooling degree days
Jan4708
Feb32120
Mar18461
Apr52145
May4345
Jun0517
Jul0606
Aug0614
Sep1423
Oct44195
Nov21948
Dec42314

Dallas-Fort Worth, TX

Cooling: Jun–SepHeating: Dec–Feb

2,412 plumbing, heating and air-conditioning contractors (2023) · weather at Dallas Fort Worth Airport

Monthly numbers
MonthHeating degree daysCooling degree days
Jan5822
Feb4138
Mar24635
Apr82102
May10290
Jun0506
Jul0642
Aug0643
Sep3410
Oct69154
Nov28527
Dec5284

Riverside-San Bernardino, CA

Cooling: Jul–SepHeating: Dec–Feb

1,442 plumbing, heating and air-conditioning contractors (2023) · weather at Riverside Municipal Airport

Monthly numbers
MonthHeating degree daysCooling degree days
Jan2966
Feb2517
Mar18918
Apr11048
May33114
Jun2242
Jul0422
Aug0459
Sep2349
Oct31154
Nov15533
Dec3182

Los Angeles, CA

Cooling: Jul–SepNo real heating season

3,793 plumbing, heating and air-conditioning contractors (2023) · weather at Los Angeles Downtown USC Campus

Monthly numbers
MonthHeating degree daysCooling degree days
Jan2118
Feb18012
Mar14122
Apr8745
May3967
Jun4134
Jul0259
Aug0301
Sep1259
Oct15147
Nov10040
Dec2274

San Diego, CA

Cooling: Jul–SepNo real heating season

1,072 plumbing, heating and air-conditioning contractors (2023) · weather at San Diego Lindbergh Field

Monthly numbers
MonthHeating degree daysCooling degree days
Jan2093
Feb1735
Mar14210
Apr8523
May4537
Jun1075
Jul1177
Aug0230
Sep0201
Oct11106
Nov9326
Dec2211

Atlanta, GA

Cooling: Jun–SepHeating: Dec–Feb

1,821 plumbing, heating and air-conditioning contractors (2023) · weather at Atlanta Hartsfield International Airport

Monthly numbers
MonthHeating degree daysCooling degree days
Jan6271
Feb4622
Mar30817
Apr12064
May22214
Jun1386
Jul0494
Aug0470
Sep5302
Oct9988
Nov33610
Dec5502

Sacramento, CA

Cooling: Jun–SepHeating: Nov–Feb

807 plumbing, heating and air-conditioning contractors (2023) · weather at Sacramento Executive Airport

Monthly numbers
MonthHeating degree daysCooling degree days
Jan5390
Feb3810
Mar2981
Apr18118
May6095
Jun8224
Jul0338
Aug0321
Sep5230
Oct7965
Nov3351
Dec5500

Charlotte, NC

Cooling: Jun–AugHeating: Dec–Feb

960 plumbing, heating and air-conditioning contractors (2023) · weather at Charlotte Douglas Airport

Monthly numbers
MonthHeating degree daysCooling degree days
Jan7120
Feb5402
Mar39210
Apr16347
May39165
Jun2348
Jul0468
Aug0423
Sep13244
Oct15254
Nov4156
Dec6311

Washington, DC

Cooling: Jun–AugHeating: Dec–Mar

1,639 plumbing, heating and air-conditioning contractors (2023) · weather at Washington Reagan Airport

Monthly numbers
MonthHeating degree daysCooling degree days
Jan8540
Feb6990
Mar5443
Apr23632
May63132
Jun4343
Jul0496
Aug0446
Sep16238
Oct17545
Nov4552
Dec7240

San Francisco, CA

No real cooling seasonHeating: Nov–Mar

1,192 plumbing, heating and air-conditioning contractors (2023) · weather at San Francisco International Airport

Monthly numbers
MonthHeating degree daysCooling degree days
Jan4260
Feb3230
Mar2961
Apr2345
May17014
Jun9723
Jul5826
Aug4441
Sep4656
Oct10033
Nov2602
Dec4220

St. Louis, MO

Cooling: Jun–AugHeating: Dec–Feb

806 plumbing, heating and air-conditioning contractors (2023) · weather at St. Louis Lambert International Airport

Monthly numbers
MonthHeating degree daysCooling degree days
Jan1,0200
Feb7931
Mar5767
Apr26237
May72150
Jun4351
Jul0476
Aug1428
Sep32212
Oct22948
Nov5603
Dec8840

Philadelphia, PA

Cooling: Jun–AugHeating: Dec–Mar

2,118 plumbing, heating and air-conditioning contractors (2023) · weather at Philadelphia International Airport

Monthly numbers
MonthHeating degree daysCooling degree days
Jan9720
Feb8150
Mar6661
Apr33015
May10482
Jun10266
Jul0425
Aug1368
Sep28175
Oct23626
Nov5301
Dec8180

Baltimore, MD

Cooling: Jun–AugHeating: Dec–Mar

982 plumbing, heating and air-conditioning contractors (2023) · weather at Baltimore Washington International Airport

Monthly numbers
MonthHeating degree daysCooling degree days
Jan9510
Feb7940
Mar6422
Apr31819
May10990
Jun11266
Jul0411
Aug0346
Sep36163
Oct26024
Nov5441
Dec8200

New York, NY

Cooling: Jul–AugHeating: Dec–Mar

7,640 plumbing, heating and air-conditioning contractors (2023) · weather at New York Central Park Tower

Monthly numbers
MonthHeating degree daysCooling degree days
Jan9700
Feb8160
Mar6881
Apr35414
May12266
Jun15226
Jul0388
Aug1345
Sep32159
Oct24022
Nov5111
Dec8040

Portland, OR

No real cooling seasonHeating: Nov–Mar

785 plumbing, heating and air-conditioning contractors (2023) · weather at Portland International Airport

Monthly numbers
MonthHeating degree daysCooling degree days
Jan7180
Feb5840
Mar5190
Apr3672
May19621
Jun8056
Jul10171
Aug7181
Sep6173
Oct2964
Nov5380
Dec7270

Cincinnati, OH

Cooling: Jun–AugHeating: Dec–Mar

631 plumbing, heating and air-conditioning contractors (2023) · weather at Cincinnati Northern Kentucky Airport

Monthly numbers
MonthHeating degree daysCooling degree days
Jan1,0430
Feb8470
Mar6643
Apr32816
May11890
Jun12233
Jul1340
Aug2309
Sep53146
Oct29623
Nov6171
Dec9110

Seattle, WA

No real cooling seasonHeating: Nov–Mar

1,064 plumbing, heating and air-conditioning contractors (2023) · weather at Seattle Tacoma International Airport

Monthly numbers
MonthHeating degree daysCooling degree days
Jan6870
Feb5880
Mar5570
Apr4121
May2429
Jun11829
Jul3196
Aug2498
Sep10230
Oct3490
Nov5550
Dec7110

Boston, MA

Cooling: Jul–AugHeating: Dec–Mar

2,169 plumbing, heating and air-conditioning contractors (2023) · weather at Boston Logan International Airport

Monthly numbers
MonthHeating degree daysCooling degree days
Jan1,0860
Feb9300
Mar8280
Apr4964
May23429
Jun50138
Jul4284
Aug5245
Sep7191
Oct3269
Nov6080
Dec9080

Pittsburgh, PA

Cooling: Jun–AugHeating: Nov–Mar

843 plumbing, heating and air-conditioning contractors (2023) · weather at Pittsburgh International Airport

Monthly numbers
MonthHeating degree daysCooling degree days
Jan1,1200
Feb9410
Mar7851
Apr4139
May17256
Jun30160
Jul3256
Aug7219
Sep8685
Oct37011
Nov6720
Dec9720

Chicago, IL

Cooling: Jun–AugHeating: Dec–Mar

3,042 plumbing, heating and air-conditioning contractors (2023) · weather at Chicago O'Hare International Airport

Monthly numbers
MonthHeating degree daysCooling degree days
Jan1,2340
Feb1,0150
Mar8082
Apr4688
May19860
Jun31199
Jul2326
Aug4277
Sep77116
Oct35515
Nov7130
Dec1,0690

Denver, CO

Cooling: Jul–AugHeating: Nov–Mar

1,183 plumbing, heating and air-conditioning contractors (2023) · weather at Denver International Airport

Monthly numbers
MonthHeating degree daysCooling degree days
Jan1,0340
Feb9040
Mar7260
Apr5171
May26126
Jun52147
Jul4315
Aug9254
Sep10599
Oct4367
Nov7670
Dec1,0480

Detroit, MI

Cooling: Jun–AugHeating: Dec–Mar

1,107 plumbing, heating and air-conditioning contractors (2023) · weather at Detroit Metro Airport

Monthly numbers
MonthHeating degree daysCooling degree days
Jan1,2160
Feb1,0360
Mar8611
Apr4884
May19850
Jun28176
Jul2283
Aug7233
Sep9190
Oct38210
Nov7120
Dec1,0460

Minneapolis-St. Paul, MN

Cooling: Jul–AugHeating: Dec–Mar

1,015 plumbing, heating and air-conditioning contractors (2023) · weather at Minneapolis/St. Paul Airport

Monthly numbers
MonthHeating degree daysCooling degree days
Jan1,5130
Feb1,2430
Mar9830
Apr5424
May21445
Jun34175
Jul4294
Aug10220
Sep12884
Oct4898
Nov9060
Dec1,3330

Sources: NOAA U.S. Climate Normals 1991–2020, monthly and Census County Business Patterns 2023 (metro areas), both read October 14, 2026. The data on this page: hvac-busy-season-calendar.csv, CC BY 4.0. Published October 18, 2026.

About the data. Where it comes from and how to use it.

What are degree days?

A standard measure of how much heating or cooling a day needs: how far its average temperature sits below or above 65°F. A month’s total shows how hard heating or cooling works that month.

How is a busy month decided?

Heating and cooling are judged apart, because winter numbers run larger than summer ones. A heating month reaches 60% of the metro’s coldest month, if that month is a real winter (300 heating degree days or more). A cooling month reaches 60% of its hottest month, if that month is a real summer (200 cooling degree days or more).

When is HVAC slow season?

In the months between the two peaks, so it moves with the climate. Here a slow month is one that is neither a heating nor a cooling month. Across most of the Northeast and Midwest that is April and May, then September to November (New York, Boston and Minneapolis add June). In Texas, Atlanta and Las Vegas it is March to May, then October and November; Houston’s spring is shorter, March and April. Florida is slow from November to April, Phoenix from October to May, and Seattle, Portland and San Francisco from April to October. Each metro’s own months are in its calendar above.

Where does the data come from?

NOAA’s U.S. Climate Normals for 1991–2020, at each metro’s main airport station, and the Census Bureau’s County Business Patterns for 2023, where NAICS 238220 counts plumbing and HVAC contractors together. Both were read in October 2026.

Can I use it?

Yes. Download the CSV and use it under CC BY 4.0: credit Fuseflow AI and link to this page.

Why isn’t my city here?

This first version covers 30 large US metro areas. Write to us at contact@fuseflow-ai.com, and we’ll look at adding yours.

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