content: <?xml version="1.0" encoding="UTF-8"?><edgarSubmission xmlns="http://www.sec.gov/edgar/ownership" xmlns:com="http://www.sec.gov/edgar/common">
    <headerData>
      <submissionType>144</submissionType>
      <filerInfo>
        <filer>
          <filerCredentials>
            <cik>0001527678</cik>
            <ccc>XXXXXXXX</ccc>
          </filerCredentials>
        </filer>
        <liveTestFlag>LIVE</liveTestFlag>
  
  
      </filerInfo>
    </headerData>
    <formData>
      <issuerInfo>
        <issuerCik>0001035983</issuerCik>
        <issuerName>COMFORT SYSTEMS USA, INC.</issuerName>
        <secFileNumber>001-13011</secFileNumber>
        <issuerAddress>
          <com:street1>675 BERING DRIVE</com:street1>
          <com:street2>SUITE 400</com:street2>
          <com:city>HOUSTON</com:city>
          <com:stateOrCountry>TX</com:stateOrCountry>
          <com:zipCode>77057</com:zipCode>
        </issuerAddress>
        <issuerContactPhone>713-830-9600</issuerContactPhone>
        <nameOfPersonForWhoseAccountTheSecuritiesAreToBeSold>SANDBROOK WILLIAM J</nameOfPersonForWhoseAccountTheSecuritiesAreToBeSold>
        <relationshipsToIssuer>
          <relationshipToIssuer>Director</relationshipToIssuer>
        </relationshipsToIssuer>
      </issuerInfo>
      <securitiesInformation>
        <securitiesClassTitle>COMMON</securitiesClassTitle>
        <brokerOrMarketmakerDetails>
          <name>RBC CAPITAL MARKETS</name>
          <address>
            <com:street1>250 NICOLLET MALL</com:street1>
            <com:street2>SUITE 1700</com:street2>
            <com:city>MINNEAPOLIS</com:city>
            <com:stateOrCountry>MN</com:stateOrCountry>
            <com:zipCode>55401</com:zipCode>
          </address>
        </brokerOrMarketmakerDetails>
        <noOfUnitsSold>5000</noOfUnitsSold>
        <aggregateMarketValue>925927.00</aggregateMarketValue>
        <noOfUnitsOutstanding>35714815</noOfUnitsOutstanding>
        <approxSaleDate>11/09/2023</approxSaleDate>
        <securitiesExchangeName>NYSE</securitiesExchangeName>
      </securitiesInformation>
      <securitiesToBeSold>
        <securitiesClassTitle>COMMON</securitiesClassTitle>
        <acquiredDate>05/19/2023</acquiredDate>
        <natureOfAcquisitionTransaction>STOCK GRANT</natureOfAcquisitionTransaction>
        <nameOfPersonfromWhomAcquired>ISSUER</nameOfPersonfromWhomAcquired>
        <isGiftTransaction>N</isGiftTransaction>
        <amountOfSecuritiesAcquired>1065</amountOfSecuritiesAcquired>
        <paymentDate>05/19/2023</paymentDate>
        <natureOfPayment>N/A</natureOfPayment>
      </securitiesToBeSold>
      <securitiesToBeSold>
        <securitiesClassTitle>COMMON</securitiesClassTitle>
        <acquiredDate>05/17/2022</acquiredDate>
        <natureOfAcquisitionTransaction>STOCK GRANT</natureOfAcquisitionTransaction>
        <nameOfPersonfromWhomAcquired>ISSUER</nameOfPersonfromWhomAcquired>
        <isGiftTransaction>N</isGiftTransaction>
        <amountOfSecuritiesAcquired>1869</amountOfSecuritiesAcquired>
        <paymentDate>05/17/2022</paymentDate>
        <natureOfPayment>N/A</natureOfPayment>
      </securitiesToBeSold>
      <securitiesToBeSold>
        <securitiesClassTitle>COMMON</securitiesClassTitle>
        <acquiredDate>05/18/2021</acquiredDate>
        <natureOfAcquisitionTransaction>STOCK GRANT</natureOfAcquisitionTransaction>
        <nameOfPersonfromWhomAcquired>ISSUER</nameOfPersonfromWhomAcquired>
        <isGiftTransaction>N</isGiftTransaction>
        <amountOfSecuritiesAcquired>1939</amountOfSecuritiesAcquired>
        <paymentDate>05/18/2021</paymentDate>
        <natureOfPayment>N/A</natureOfPayment>
      </securitiesToBeSold>
      <securitiesToBeSold>
        <securitiesClassTitle>COMMON</securitiesClassTitle>
        <acquiredDate>05/19/2020</acquiredDate>
        <natureOfAcquisitionTransaction>STOCK GRANT</natureOfAcquisitionTransaction>
        <nameOfPersonfromWhomAcquired>ISSUER</nameOfPersonfromWhomAcquired>
        <isGiftTransaction>N</isGiftTransaction>
        <amountOfSecuritiesAcquired>127</amountOfSecuritiesAcquired>
        <paymentDate>05/19/2020</paymentDate>
        <natureOfPayment>N/A</natureOfPayment>
      </securitiesToBeSold>
      <nothingToReportFlagOnSecuritiesSoldInPast3Months>Y</nothingToReportFlagOnSecuritiesSoldInPast3Months>
      <noticeSignature>
        <noticeDate>11/09/2023</noticeDate>
        <signature>JEFFREY J. KAPALA</signature>
      </noticeSignature>
    </formData>
  </edgarSubmission>
metadata_documents: [{"type": "144", "sequence": "1", "filename": "primary_doc.xml", "secsgml_size_bytes": 4332}]
text: 144
  0001527678
  XXXXXXXX
  LIVE
  0001035983
  COMFORT SYSTEMS USA, INC.
  001-13011
  675 BERING DRIVE
  SUITE 400
  HOUSTON
  TX
  77057
  713-830-9600
  SANDBROOK WILLIAM J
  Director
  COMMON
  RBC CAPITAL MARKETS
  250 NICOLLET MALL
  SUITE 1700
  MINNEAPOLIS
  MN
  55401
  5000
  925927.00
  35714815
  11/09/2023
  NYSE
  COMMON
  05/19/2023
  STOCK GRANT
  ISSUER
  N
  1065
  05/19/2023
  N/A
  COMMON
  05/17/2022
  STOCK GRANT
  ISSUER
  N
  1869
  05/17/2022
  N/A
  COMMON
  05/18/2021
  STOCK GRANT
  ISSUER
  N
  1939
  05/18/2021
  N/A
  COMMON
  05/19/2020
  STOCK GRANT
  ISSUER
  N
  127
  05/19/2020
  N/A
  Y
  11/09/2023
  JEFFREY J. KAPALA