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

    <schemaVersion>X0306</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2016-04-28</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0001396633</issuerCik>
        <issuerName>SUMMER ENERGY HOLDINGS INC</issuerName>
        <issuerTradingSymbol>SUME</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001116185</rptOwnerCik>
            <rptOwnerName>LEIBMAN NEIL</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>800 BERING DRIVE</rptOwnerStreet1>
            <rptOwnerStreet2>SUITE 260</rptOwnerStreet2>
            <rptOwnerCity>HOUSTON</rptOwnerCity>
            <rptOwnerState>TX</rptOwnerState>
            <rptOwnerZipCode>77057</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>1</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle>Chief Executive Officer</officerTitle>
            <otherText></otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2016-04-28</value>
            </transactionDate>
            <deemedExecutionDate></deemedExecutionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>J</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness></transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>22708</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>0</value>
                    <footnoteId id="F1"/>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>759026</value>
                    <footnoteId id="F2"/>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <footnotes>
        <footnote id="F1">The reporting person received these shares of common stock in connection with a personal guaranty given by the reporting person for the benefit of the Issuer in connection with an Advance-to-Loan Amount Note, whereby the Issuer borrowed funds from a lending institution. In consideration of such personal guaranty, the Issuer agreed to grant up to 30,000 shares of common stock per month, reduced accordingly as the principal amount of the Note is reduced.</footnote>
        <footnote id="F2">Does not include 46,479 shares held of record by Boxer Capital, Ltd., a Texas LP. Mr. Leibman is general partner of such entity and has sole voting and dispositive power over such shares. Also does not include 1,807,576 shares held of record by MAA Holdings Limited, a Texas LP. Mr. Leibman is general partner of such entity and has sole voting and dispositive power over such shares. Also does not include 24,442 shares held of record by Northeast Opco, LLC, a Texas LLC. Mr. Leibman is a control person and 20% owner of such entity and shares voting and dispositive power over such shares. Mr. Leibman disclaims beneficial ownership of the reported securities except to the extent of his pecuniary interest therein, and this report shall not be deemed an admission that such reporting person is the beneficial owner of the securities for purposes of Section 16 of the Exchange Act, or for any other purpose.</footnote>
    </footnotes>

    <remarks>By Alexander N. Pearson, pursuant to a power of attorney dated December 12, 2012, included as Exhibit 24.1 to Schedule 13G filed on December 12, 2012.</remarks>

    <ownerSignature>
        <signatureName>/s/ NEIL LEIBMAN</signatureName>
        <signatureDate>2016-04-29</signatureDate>
    </ownerSignature>
</ownershipDocument>
