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

    <schemaVersion>X0202</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2007-01-03</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

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

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001169479</rptOwnerCik>
            <rptOwnerName>BECK RONALD H</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>2 NORTH CASCADE AVENUE</rptOwnerStreet1>
            <rptOwnerStreet2>C/O WESTMORELAND COAL COMPANY</rptOwnerStreet2>
            <rptOwnerCity>COLORADO SPRINGS</rptOwnerCity>
            <rptOwnerState>CO</rptOwnerState>
            <rptOwnerZipCode>80903</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>1</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle>VP-Finance and Treasurer</officerTitle>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
                <footnoteId id="F1"/>
            </securityTitle>
            <transactionDate>
                <value>2007-01-03</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>S</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
                <footnoteId id="F2"/>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>500</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>20</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>500</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
                <footnoteId id="F1"/>
            </securityTitle>
            <transactionDate>
                <value>2007-01-03</value>
                <footnoteId id="F3"/>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>I</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
                <footnoteId id="F4"/>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>39</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>19.67</value>
                    <footnoteId id="F5"/>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>166</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>401(k)</value>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <footnotes>
        <footnote id="F1">$2.50 par value per share.</footnote>
        <footnote id="F2">The sale represented on this Form 4 was effected pursuant to a pre-existing Rule 10b5-1 plan, adopted by the reporting person in November 2006.</footnote>
        <footnote id="F3">Shares acquired at various dates from 11/22/06 to 01/03/07.</footnote>
        <footnote id="F4">No transaction took place.  This information is required for electronic filing purposes only.</footnote>
        <footnote id="F5">Price reflects the most recent date of acquisition.</footnote>
    </footnotes>

    <ownerSignature>
        <signatureName>/s/Diane S. Jones, VP, Corporate Relations, by Power of Attorney</signatureName>
        <signatureDate>2007-01-05</signatureDate>
    </ownerSignature>
</ownershipDocument>
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X0202
4
2007-01-03
0
0000106455
WESTMORELAND COAL CO
WLB
0001169479
BECK RONALD H
2 NORTH CASCADE AVENUE
C/O WESTMORELAND COAL COMPANY
COLORADO SPRINGS
CO
80903
0
1
0
0
VP-Finance and Treasurer
Common Stock
2007-01-03
4
S
0
500
20
D
500
D
Common Stock
2007-01-03
4
I
0
39
19.67
A
166
I
401(k)
$2.50 par value per share.
The sale represented on this Form 4 was effected pursuant to a pre-existing Rule 10b5-1 plan, adopted by the reporting person in November 2006.
Shares acquired at various dates from 11/22/06 to 01/03/07.
No transaction took place.  This information is required for electronic filing purposes only.
Price reflects the most recent date of acquisition.
/s/Diane S. Jones, VP, Corporate Relations, by Power of Attorney
2007-01-05