Advice
January's weather
Coldest month
This is one of the coldest months of the year, particularly for inland areas (coastal areas are at their coldest next month).
A clear sky and a still day could herald hard frost. Snow is to be expected in NE Scotland, and could occur anywhere, though usually only in inland areas north of the UK south coast. Snowfall during UK winters is variable and notoriously difficult to predict. But gales and rain can make it feel almost as cold as it does on a frosty or snowy day.
Temperature
The last three Januaries have all been warmer than the long-term UK averages for this time of year. Even so, mean temperatures have hovered around 3-6°C (37-43°F), with minimum temperatures dropping to around 1-2°C (34-36°F), or less in cold areas. This is challenging for plants that are not quite hardy in the UK, especially if the extra chill persists for more than the occasional night and if the soil freezes.
If this winter is as hard as some well-publicised reports have forecast, then we could expect UK means as low as 2-3°C (36-37°F), with minimum temperatures, nights and colder areas dropping well below this.
Inland areas and areas of low ground are the coldest, with valleys becoming potential frost pockets. Coastal areas are usually milder, although more prone to driving winds and rain.
Rain
This is a wet time of year in many parts of the UK, with all areas experiencing a winter peak in precipitation. But local topography can affect rainfall enormously, with dramatic local variations.
Eastern Scotland generally receives around 116mm in January, which is similar to the overall UK average. Western Scotland, by contrast can expect more in the region of 180mm, although 250mm is not at all unusual at this time of year.
East Anglia, as usual, is one of the driest regions, expecting a mean of around 50mm rainfall in January. Northern England can expect about 90mm, SW England and Northern Ireland can expect 120mm, the Midlands, the South and the SE of England about 80mm, and Wales (overall) around 150mm. Obviously, it is the hills and any coastal regions that will receive the bulk of the rain in these regional averages.
Yearly rainfall averages are very variable, with January 2005 being much wetter than average for Scotland, dryer than average for England and Wales, and on par for Northern Ireland. January 2004 was generally wetter than average, and January 2003 was closer to long-term UK averages throughout.
Wind
Gale-force winds are a problem for the UK in January. The northern half of the UK is usually worst affected, particularly towards the western coastal regions, where gales can be severe.
Areas of higher ground and coastal fringes usually receive the worst of the winds. Combined with rain, this makes for unpleasant conditions.
Your garden needs protection just as you do - stakes, ties, fleece wraps, cloches, supports and wayward branches will all need regular checking for damage. Plants can suffer from wind rock at the roots, which will affect their health and vigour the following spring.
Sunshine
The South and the East of the UK fare the best for sunshine in January. This is partly due to the topography of the UK landmass. Western and northern regions are hillier than the eastern and southern regions, so they receive less of the sun when it is low in the sky during winter.
Average hours of sunshine for this month are: 45 hours in northern England and northern Wales, 48 hours in the Midlands, in SW England and southern Wales, and 53 hours in East Anglia, southern and South East England. Northern Ireland can expect 44 hours of sunshine.
Northern Scotland can expect 27.5 hours, western Scotland about 38 hours, and eastern Scotland more like 41 hours of sunshine.
This lack of light limits growth of plants in greenhouses, conservatories and windowsills. Moving them to a sunnier position over the winter is advised. The shorter days at this time of year can induce flowering in some plants, such as poinsettias and chrysanthemums.