Blackpool Wren Rovers were two up at Poolfoot Farm through Olly Hesford and Jordan Wood. But Billy Cartmell on 55 minutes and Jake Mangan 10 minutes later levelled it up.
Tom Slater then popped up in injury time to make it four wins from four games for Thornton.
In the only other game in the division to beat the weather, Fulwood Amateurs Reserves won 3-0 at Poulton.
Alex Smithson and Billy Dewhurst scored in quick succession in the first half with Hugo Strand adding the cherry on top in the second period.
In Division Two Reserve, Freckleton are top after an 8-0 demolition of Rossendale A which remarkably featured eight different scorers.
Danny Thompson, Guillermo Marchant, Brad Jones, Callum Williams and Lewis Masters made It 5-0 at the break and Mohamed Soliman, Jimmy Richardson and Max Newby completed the rout in the second half.
Hesketh Bank are in second on goal difference thanks to a 3-0 win over Lytham Town.
John Ashcroft set the ball rolling before Connor Murphy plastered his name on the scoresheet just three minutes later. Jonathan Croft grabbed the third.
Ben Davies goal on 55 minutes for Croston earned them three points against Fulwood Amateurs A and Milnthorpe Cornithians earned their first points of the season coming from behind to win at Storeys 2-1, Lewis Airey and Will Booth netting in the second half after Josh Heap’s opener for the hosts.
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