Voters are going to the polls in by-elections in Stoke-on-Trent Central and Copeland.
Polling stations will be open from 07:00 until 22:00 GMT.
Voting will take place as Storm Doris, forecast to bring heavy rain and winds of 80mph, is expected to cross central and northern parts of England.
The contests follow the resignations of Labour MPs Tristram Hunt, in Stoke-on-Trent Central and Jamie Reid, in Copeland, in Cumbria.
Stoke-on-Trent Central candidates, in alphabetical order
Mohammed Yaqub Akram – Independent
Zulfiqar Ali – Liberal Democrats
Jack Brereton – Conservatives
The Incredible Flying Brick – Official Monster Raving Loony Party
Adam Colclough – Green Party
Godfrey Davies – Christian Peoples Alliance
Barbara Fielding – Independent
David Furness – British National Party Local People First
Paul Nuttall – UKIP
Gareth Snell – Labour
Copeland candidates, in alphabetical order
Michael Guest – Independent
Rebecca Hanson – Liberal Democrats
Trudy Harrison – Conservatives
Roy Ivinson – Independent
Jack Lenox – Green Party
Fiona Mills – UKIP
Gillian Troughton – Labour