It's an urban myth that bonfires are illegal at certain times of the day, but that doesn't mean you can't fall foul of the law by having one. Here is the advice from the authority on the subject...(Dorset County Council)
Having a bonfire?
If you have considered the alternatives ( composting, trip to the recycling centre, garden waste collection) and a bonfire is still the best practical option for disposing of your garden waste, you should ensure you have taken the following precautions:
Warn your neighbours - lighting a bonfire can cause nuisance to your neighbours especially if it is a nice sunny day with washing out and windows open
Only burn dry material - this is likely to cause less smoke
Never burn household rubbish, rubber tyres or anything containing plastic, foam or paint - these can cause harmful emissions
Never use old engine oil, meths or petrol to light or encourage the fire
Avoid lighting a fire in unsuitable weather conditions - smoke hangs in the air on damp days and in the evening. If it is windy smoke may be blown into neighbour gardens and across roads
Avoid burning at weekends and on bank holidays when people want to enjoy their gardens
Never leave a fire unattended or leave it to smoulder
The law on bonfires
Bonfires are only illegal if they cause a nuisance to others. It is commonly thought that there are byelaws banning bonfires or restricting the days or times when they are allowed - there aren't.
Burning waste from another site
It is an offence to bring waste from another site and burn it, for example tradesmen bringing waste home and burning it. Whether or not they are causing a statutory nuisance, they are committing an offence.
Hazard to road users
If the smoke from a bonfire poses a hazard to road users the police have powers to deal with it and you should report the incident to them.
Environmental Protection Act 1990
Environmental Protection Act 1990 can be used to deal with people who act unreasonably and cause a statutory nuisance to neighbours. To be considered a statutory nuisance, a bonfire would usually have to be a persistent problem. If someone does cause a repeated nuisance this may lead to enforcement action, and ultimately legal proceedings could be taken and the person fined up to £5,000.
Contacts for reporting a bonfire nuisance
North Dorset District Council Customer Services
Tel: 01258 454111. Fax: 01258 484185. Mobile: 07781 472878 (Text SMS)