Advice
October's weather
Autumn chill sets in and the days are much shorter. The growing season is all but over.
Although we had some cooler days over September, the autumn is now definitely here for real, and it feels colder. Despite occasional warm days, there is a chill in the air, particularly in the mornings and evenings. The reduced day length is very noticeable. Frosts are more likely. Gales and rain are to be expected, and there may even be a little snow on higher ground in the north of Scotland and Northern Ireland.
Regional differences become increasingly marked, with Scotland, Northern Ireland and northern England feeling much more autumnal than the southern tip of the UK.
Make the most of the remaining warmth while you can!
Temperature
Mean temperatures during October vary between 7-8°C (45-46°F) in northern Scotland, to 11°C (52°F) in southern England, with the north of England and Northern Ireland experiencing means between 8-9.5°C (46-50°F), and the Midlands settling in at about 10°C (50°F).
However, the gap between the minimum and maximum temperatures over the 24-hour cycle is widening.
Temperatures as low as -3 to -4°C (25-27°F)were recorded overnight last year in northern Scotland and Northern Ireland. Slight air frosts can occur in October, even in areas of southern England - parts of Surrey for example.
On warm days, the temperatures can reach 14-15°C (57-60°F) in southern England, 13.5°C (56°F) in the Midlands and southern Wales, 12-13°C (54-55°F) in northern England and Northern Ireland, and 10-11°C (50-52°F) in Scotland. Within Scotland, the west is usually slightly warmer than the east, but only by about 1°C (2°F).
Gardeners should therefore be prepared for frost. In cold areas, you should already have moved your tender plants into the house, or to a heated greenhouse. In mild areas you may be able to overwinter things in the garden, but you should have fleece, together with straw, bracken, paper or some other packing material, on hand in order to cover the more tender plants. A thick layer of mulch over the died-down crowns of tender herbaceous plants can also be effective in ensuring their return next spring.
Rain
Rainfall is very variable in October, with both wet, stormy and cold, dry weather both possible. Yearly rainfall averages for October can frequently be both well above and well below mean levels.
Western Scotland usually has the most rain, with Scotland experiencing more rain than England, Wales and Northern Ireland.
More than 200mm of October rain is common in the Scottish highlands, with 110-120mm being likely in central and eastern parts of Scotland, the borders and the north of England.
75mm of October rainfall is around average for the Midlands and for central southern areas of England; 100mm is common in the south west of England; 120-125mm could be expected in Northern Ireland; East Anglia is generally the driest region with 50-60mm being possible over the month.
Snowfall is possible this month, but is only likely in the northernmost parts of Scotland and Northern Ireland, and only on higher ground.
Be prepared for all possibilities. Do not rely on heavy autumn rains to take care of watering new plants, unless you live in an area with very predictable rain at this time of year. October 2003 saw 58% of the average rainfall for this month, which only compounded the summer drop in the water table. If you do need to supplement rainfall and water new or transplanted trees, shrubs and perennials, then use stored rainwater or recycled grey water wherever possible.
If there are heavy rains forecast, make sure that you have supported, tied in and pruned (if appropriate) all herbaceous plants and climbers, and that any newly planted trees are well staked.
Wind
Winds pick up as the autumn progresses, with gales being more likely. The winds will blow the autumn leaves off the trees, creating a lot of clearing up work in the garden and putting an end to displays of beautiful autumn colour.
The north and west of the UK (i.e. Scotland, Wales and northern England) usually have the worst of the gales, with southern areas and East Anglia getting off more lightly. Coastal areas generally have stronger winds than inland regions.
Wind-chill can make the weather feel colder, and can scorch the leaves of plants such as acers, which are mainly grown for their beautiful leaf colours and forms. Increasing the shelter in your garden may help with this problem.
Sunshine
The day length is now noticeably shorter, and the angle of the sun more acute, with decreased intensity. These are limiting factors to plant growth, together with lower temperatures and gusty winds.
The south coast of England always has the greatest amount of sunshine in October (100-108 hours on average, but reaching 150 hours in a good year). However, despite the indisputable fact that northern areas of the UK generally have shorter days than southern areas, the Scottish Highlands actually compare favourably with northern and central England when average hours of sunshine are compared in October (88 hours average in Wick, but only 86 hours average in Nottingham, for example). Northern Ireland generally experiences about 80-85 hours of sunshine over October, and Wales about 90 hours.