A straw bale set on fire in Wisbech and an out of control bonfire in March were attended to by fire crews.
The incidents happened yesterday (Monday August 12) between 2pm and 5.30pm.
Firefighters were first called to an unattended bonfire containing plastics on Peyton Avenue in March.
They then were alerted to two broken bales of straw on fire in a field.
The cause of both was accidental.
Shortly after they attended a straw bale that had deliberately been set alight in Redmoor Lane in Wisbech.
It comes as police and fire officers are urging the public to be vigilant and report suspicious behaviour in a bid to prevent arsons in the county.
The plea is part of the force's #SaferSummer campaign and comes at a time when there are often more offences, influenced by warm dry weather, school holidays and harvest season.
Sergeant Craig Flavell, from the force's rural crime action team (RCAT), said the summer months see an increase in rural arsons, with the harvest resulting in an increase in stack fires, when hay bales are deliberately set on fire.
Anyone with information should about the fire in Redmoor Lane should contact police by visiting www.cambs.police.uk to submit an online report or call Crimestoppers on 0800 555111.
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