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

    <schemaVersion>X0206</schemaVersion>

    <documentType>3/A</documentType>

    <periodOfReport>2010-02-11</periodOfReport>

    <dateOfOriginalSubmission>2010-03-09</dateOfOriginalSubmission>

    <noSecuritiesOwned>0</noSecuritiesOwned>

    <issuer>
        <issuerCik>0000811808</issuerCik>
        <issuerName>SUMMIT FINANCIAL GROUP INC</issuerName>
        <issuerTradingSymbol>SMMF</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001486521</rptOwnerCik>
            <rptOwnerName>George Georgette R.</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>PO BOX 8523</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>CHARLESTON</rptOwnerCity>
            <rptOwnerState>WV</rptOwnerState>
            <rptOwnerZipCode>25303</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle></officerTitle>
            <otherText></otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeHolding>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>0</value>
                    <footnoteId id="F3"/>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>By Father</value>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeHolding>
    </nonDerivativeTable>

    <derivativeTable>
        <derivativeHolding>
            <securityTitle>
                <value>8% Non-Cumulative Convertible Preferred Stock, Series 2009</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>5.50</value>
            </conversionOrExercisePrice>
            <exerciseDate>
                <value>2010-03-01</value>
                <footnoteId id="F1"/>
            </exerciseDate>
            <expirationDate>
                <value>2019-06-01</value>
                <footnoteId id="F1"/>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>18181.81</value>
                    <footnoteId id="F2"/>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>By Sellaro Enterprise</value>
                </natureOfOwnership>
            </ownershipNature>
        </derivativeHolding>
        <derivativeHolding>
            <securityTitle>
                <value>8% Non-Cumulative Convertible Preferred Stock, Series 2009</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>5.50</value>
            </conversionOrExercisePrice>
            <exerciseDate>
                <value>2010-03-01</value>
                <footnoteId id="F1"/>
            </exerciseDate>
            <expirationDate>
                <value>2019-06-01</value>
                <footnoteId id="F1"/>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>0</value>
                    <footnoteId id="F3"/>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>By Father-in-Law and Mother-in-law</value>
                </natureOfOwnership>
            </ownershipNature>
        </derivativeHolding>
        <derivativeHolding>
            <securityTitle>
                <value>8% Non-Cumulative Convertible Preferred Stock, Series 2009</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>5.50</value>
            </conversionOrExercisePrice>
            <exerciseDate>
                <value>2010-03-01</value>
                <footnoteId id="F1"/>
            </exerciseDate>
            <expirationDate>
                <value>2019-06-01</value>
                <footnoteId id="F1"/>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>0</value>
                    <footnoteId id="F3"/>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>By Mother</value>
                </natureOfOwnership>
            </ownershipNature>
        </derivativeHolding>
    </derivativeTable>

    <footnotes>
        <footnote id="F1">The 2009 Series Preferred Stock may be converted at the holder's option on any dividend payment date.</footnote>
        <footnote id="F2">The reporting person did not report on her original Form 3 her spouse's indirect ownership through a company controlled by him of 18,181 shares of common stock into which the 8% Non-Cumulative Convertible Preferred Stock, Series 2009 could be converted.  These shares were also omitted from 5 subsequent Form 4s filed since the initial Form 3 filing.</footnote>
        <footnote id="F3">The reporting person inadvertently reported indirect beneficial ownership of shares owned by her mother and father and her mother-in-law and father-in-law.  Shares owned directly and indirectly by these individuals were also inadvertently reported on 5 Forms 4 filed since the initial Form 3 filing.</footnote>
    </footnotes>

    <remarks></remarks>

    <ownerSignature>
        <signatureName>Teresa D. Ely, Lmtd POA Attorney-In-Fact</signatureName>
        <signatureDate>2015-07-23</signatureDate>
    </ownerSignature>
</ownershipDocument>
