A rare weather phenomenon could hit Bucks and the south east tomorrow.
The Met Office has issued a yellow weather warning which means we could see "Thundersnow".
Snow, wind and heavy rain could affect the county tomorrow (Thursday January 12) and the Met Office warned of disruption to road, rail and air travel.
The yellow warning of snow, which has been extended to last until 11.55pm, is expected to start at 10am.
The warning, on the Met Office website, read: "Rain moving eastwards across the south of the UK on Thursday may turn to snow in places.
"There is a chance of snow settling with disruption to road, rail and air services as well as interruptions to power supplies and other utilities - this is more likely across East Anglia and southeast England.
"Associated heavy rain and strong winds may prove additional hazards.
"As skies clear on Thursday night there is also potential for widespread ice to form quite rapidly on untreated surfaces."
Chesham will see highs of 2 and lows of a chilly -7.
But it is expected to be worse in other parts of the country with severe weather warnings issued elsewhere.
What is thundersnow?
It's a type of storm where snow falls instead of rain.
Those caught in a thundersnow can expect the usual lightning and thunder which comes with an ordinary storm, but rainfall is swapped with snow.
It happens when thunderstorms form in wintry conditions.
A strong movement of upwards air needs to combine with warm air wrapping amidst it to create the unusual occurence.
Exact locations are difficult to predict, but yellow warnings for wind and snow affect all of Scotland, most of Wales and Northern Ireland, and the south east area.
Those areas will be affected by showers and snow from winter storms, which carry a risk of thundersnow, at varying points over the coming days.
The thundersnow could develop between Wednesday and Friday in the right conditions.
On Thursday the warnings expand to include Wales and eastern England, and will continue into Friday, affecting much of Britain.