<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0306</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2013-04-29</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0000106455</issuerCik>
        <issuerName>WESTMORELAND COAL Co</issuerName>
        <issuerTradingSymbol>WLB</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0000948904</rptOwnerCik>
            <rptOwnerName>GENDELL JEFFREY L ET AL</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>1 SOUND SHORE DRIVE</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>GREENWICH</rptOwnerCity>
            <rptOwnerState>CT</rptOwnerState>
            <rptOwnerZipCode>06830</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001276922</rptOwnerCik>
            <rptOwnerName>TONTINE CAPITAL PARTNERS L P</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>1 SOUND SHORE DRIVE</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>GREENWICH</rptOwnerCity>
            <rptOwnerState>CT</rptOwnerState>
            <rptOwnerZipCode>06830</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001272374</rptOwnerCik>
            <rptOwnerName>TONTINE CAPITAL MANAGEMENT LLC</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>1 SOUND SHORE DRIVE</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>GREENWICH</rptOwnerCity>
            <rptOwnerState>CT</rptOwnerState>
            <rptOwnerZipCode>06830</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001269122</rptOwnerCik>
            <rptOwnerName>TONTINE PARTNERS L P</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>1 SOUND SHORE DRIVE</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>GREENWICH</rptOwnerCity>
            <rptOwnerState>CT</rptOwnerState>
            <rptOwnerZipCode>06830</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001268959</rptOwnerCik>
            <rptOwnerName>TONTINE MANAGEMENT LLC</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>1 SOUND SHORE DRIVE</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>GREENWICH</rptOwnerCity>
            <rptOwnerState>CT</rptOwnerState>
            <rptOwnerZipCode>06830</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001268961</rptOwnerCik>
            <rptOwnerName>TONTINE OVERSEAS ASSOCIATES LLC</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>1 SOUND SHORE DRIVE</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>GREENWICH</rptOwnerCity>
            <rptOwnerState>CT</rptOwnerState>
            <rptOwnerZipCode>06830</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001482608</rptOwnerCik>
            <rptOwnerName>TONTINE CAPITAL OVERSEAS MASTER FUND II, L.P.</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>1 SOUND SHORE DRIVE</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>GREENWICH</rptOwnerCity>
            <rptOwnerState>CT</rptOwnerState>
            <rptOwnerZipCode>06830</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001482609</rptOwnerCik>
            <rptOwnerName>TONTINE ASSET ASSOCIATES, L.L.C.</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>1 SOUND SHORE DRIVE</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>GREENWICH</rptOwnerCity>
            <rptOwnerState>CT</rptOwnerState>
            <rptOwnerZipCode>06830</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock, par value $2.50 per share</value>
            </securityTitle>
            <transactionDate>
                <value>2013-04-29</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>S</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>250000</value>
                    <footnoteId id="F2"/>
                </transactionShares>
                <transactionPricePerShare>
                    <value>12.00</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>2381138</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>See Footnotes</value>
                    <footnoteId id="F1"/>
                    <footnoteId id="F3"/>
                    <footnoteId id="F4"/>
                    <footnoteId id="F5"/>
                    <footnoteId id="F6"/>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <footnotes>
        <footnote id="F1">This report is filed jointly by Tontine Capital Partners, L.P., a Delaware limited partnership (&quot;TCP&quot;), Tontine Capital Management, L.L.C., a Delaware limited liability company (&quot;TCM&quot;), Tontine Partners, L.P., a Delaware limited partnership (&quot;TP&quot;), Tontine Management, L.L.C., a Delaware limited liability company (&quot;TM&quot;), Tontine Overseas Associates, L.L.C., a Delaware limited liability company (&quot;TOA&quot;), Tontine Capital Overseas Master Fund II, L.P., a Cayman Islands limited partnership (&quot;TCP 2&quot;), Tontine Asset Associates, L.L.C., a Delaware limited liability company (&quot;TAA&quot;) and Jeffrey L. Gendell (&quot;Mr. Gendell&quot;).  Mr. Gendell is the managing member of: (a) TCM, the general partner of TCP; (b) TM, the general partner of TP; (c) TOA, and (d) TAA, the general partner of TCP 2.</footnote>
        <footnote id="F2">On April 29, 2013, TP sold 250,000 shares of Common Stock at a price of $12.00 per share.</footnote>
        <footnote id="F3">TCP 2, TM and TAA directly own 0 shares of Common Stock, TCP directly owns 468,362 shares of Common Stock, TCM directly owns 70,000 shares of Common Stock, TP directly owns 1,195,696 shares of Common Stock, TOA directly owns 98,080 shares of Common Stock and Mr. Gendell directly owns 549,000 shares of Common Stock.</footnote>
        <footnote id="F4">All of the foregoing securities may be deemed to be beneficially owned by Mr. Gendell.  The foregoing securities held by TCP may be deemed to be beneficially owned by TCM.  The foregoing securities held by TP may be deemed to be beneficially owned by TM.  The foregoing securities held by TCP 2 may be deemed to be beneficially owned by TAA.</footnote>
        <footnote id="F5">Mr. Gendell disclaims beneficial ownership of the Issuer's securities reported herein for purposes of Section 16(a) under the Securities Exchange Act of 1934, as amended, or otherwise, except as to securities directly owned by Mr. Gendell or representing Mr. Gendell's pro rata interest in, and interest in the profits of, TCM, TCP, TP, TM, TOA, TCP 2 and TAA.  TCM disclaims beneficial ownership of the Issuer's securities reported herein for purposes of Section 16(a) under the Securities Exchange Act of 1934, as amended, or otherwise, except as to securities directly owned by TCM or representing TCM's pro rata interest in, and interest in the profits of, TCP.  TM disclaims beneficial ownership of the Issuer's securities reported herein for purposes of Section 16(a) under the Securities Exchange Act of 1934, as amended, or otherwise, except as to securities directly owned by TM or representing TM's pro rata interest in, and interest in the profits of, TP.</footnote>
        <footnote id="F6">TOA disclaims beneficial ownership of the Issuer's securities reported herein for purposes of Section 16(a) under the Securities Exchange Act of 1934, as amended, or otherwise, except as to securities directly owned by TOA. TAA disclaims beneficial ownership of the Issuer's securities reported herein for purposes of Section 16(a) under the Securities Exchange Act of 1934, as amended, or otherwise, except as to securities directly owned by TAA or representing TAA's pro rata interest in, and interest in the profits of, TCP 2.</footnote>
    </footnotes>

    <ownerSignature>
        <signatureName>Tontine Capital Partners, L.P., By: its General Partner, Tontine Capital Management, L.L.C., By: its Managing Member, /s/ Jeffrey L. Gendell</signatureName>
        <signatureDate>2013-05-01</signatureDate>
    </ownerSignature>

    <ownerSignature>
        <signatureName>Tontine Capital Management, L.L.C., By: its Managing Member, /s/ Jeffrey L. Gendell</signatureName>
        <signatureDate>2013-05-01</signatureDate>
    </ownerSignature>

    <ownerSignature>
        <signatureName>Tontine Partners, L.P., By: its General Partner, Tontine Management, L.L.C., By: its Managing Member, /s/ Jeffrey L. Gendell</signatureName>
        <signatureDate>2013-05-01</signatureDate>
    </ownerSignature>

    <ownerSignature>
        <signatureName>Tontine Management, L.L.C., By: its Managing Member, /s/ Jeffrey L. Gendell</signatureName>
        <signatureDate>2013-05-01</signatureDate>
    </ownerSignature>

    <ownerSignature>
        <signatureName>Tontine Overseas Associates, L.L.C., By: its Managing Member, /s/ Jeffrey L. Gendell</signatureName>
        <signatureDate>2013-05-01</signatureDate>
    </ownerSignature>

    <ownerSignature>
        <signatureName>Tontine Capital Overseas Master Fund II, L.P. By: its General Partner, Tontine Asset Associates, L.L.C., By: its Managing Member, /s/ Jeffrey L. Gendell</signatureName>
        <signatureDate>2013-05-01</signatureDate>
    </ownerSignature>

    <ownerSignature>
        <signatureName>Tontine Asset Associates, L.L.C., By: its Managing Member, /s/ Jeffrey L. Gendell</signatureName>
        <signatureDate>2013-05-01</signatureDate>
    </ownerSignature>

    <ownerSignature>
        <signatureName>/s/ Jeffrey L. Gendell</signatureName>
        <signatureDate>2013-05-01</signatureDate>
    </ownerSignature>
</ownershipDocument>
