The sun is shining, the flowers are in bloom - and undertakers everywhere are tearing their hair out. Sydney's unseasonably mild winter, the warmest on record, might be a joy for most of us but it's making life tough for funeral directors, who are experiencing their slowest season in 25 years.

''We've seen the biggest drop in business in a generation,'' said Andrew Smith, chief executive of InvoCare, the largest private funeral, cemetery and crematorium operator in the Asia-Pacific region. ''Winter is usually our busiest time, but there's been no real flu season this year and no real cold snaps, and that's being reflected in a big drop in business.''

Grave concerns: Master funeral director Warwick Hansen, the regional manager of Hansen & Cole Funerals. Credit:Marco Del Grande

Wollongong mortician Warwick Hansen has been in the industry for 47 years. ''It's probably the slowest winter I've ever seen,'' he said. ''We've had a 10 to 15 per cent drop in the death rate. Talking to other people in the industry, suppliers and coffin makers, they are all saying they have been affected.''

Winter is traditionally the Grim Reaper's busiest period, according to Charmian Bennett, a specialist in environmental health at the National Centre for Epidemiology and Population Health, in Canberra. ''That's because most of the infectious diseases, like the flu and even coughs and colds - which can kill older people - are spread by personal contact, which increases in winter when people tend to spend more time indoors, in closer proximity to one another. But if it's a warm winter then people may spend less time inside, and such diseases don't become as prevalent.''

Sydney is experiencing its warmest winter on record, with an average maximum temperature of 19.5 degrees. Such warming is already affecting when Australians die. In a study published in April this year, Dr Bennett and her fellow researchers discovered there had been a 15 per cent shift towards summer deaths over the past 40 years. ''In the future, it looks like if this pattern continues, that heat-related deaths could outweigh cold-related deaths,'' she said.