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

    <schemaVersion>X0306</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2018-10-18</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0000107687</issuerCik>
        <issuerName>WINNEBAGO INDUSTRIES INC</issuerName>
        <issuerTradingSymbol>WGO</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001382452</rptOwnerCik>
            <rptOwnerName>Happe Michael J</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>WINNEBAGO INDUSTRIES, INC.</rptOwnerStreet1>
            <rptOwnerStreet2>P.O. BOX 152</rptOwnerStreet2>
            <rptOwnerCity>FOREST CITY</rptOwnerCity>
            <rptOwnerState>IA</rptOwnerState>
            <rptOwnerZipCode>50436</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>1</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle>CEO &amp; President</officerTitle>
            <otherText></otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock, $.50 par value</value>
            </securityTitle>
            <transactionDate>
                <value>2018-10-18</value>
            </transactionDate>
            <deemedExecutionDate></deemedExecutionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>F</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness></transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>1418</value>
                    <footnoteId id="F1"/>
                </transactionShares>
                <transactionPricePerShare>
                    <value>29.12</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>54368</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <footnotes>
        <footnote id="F1">Upon the annual incremental vesting of a restricted stock award granted 10/18/17 under the Winnebago Industries, Inc. 2014 Omnibus Equity, Performance Awards, and Incentive Compensation Plan, which is a Section 16(b) plan, the reporting person exercised their option to have a portion of such vested shares, equal in value to the tax amount calculated based upon the value of such shares on the vesting date, to be withheld by the Company in order to meet reporting person's tax obligation incurred upon the vesting of such restricted stock award.</footnote>
    </footnotes>

    <ownerSignature>
        <signatureName>/s/ Stacy Bogart, Vice President, General Counsel &amp; Secretary, Winnebago Industries, Inc. under Power of Attorney</signatureName>
        <signatureDate>2018-10-19</signatureDate>
    </ownerSignature>
</ownershipDocument>
