Scotland's climate is cool and wet with extreme variations in daylight hours—from as little as five hours in mid-winter to 20 hours in mid-summer. There's only about a 20-degree difference between average winter temperatures—in the low 40s Fahrenheit—and average summer temperatures, which are typically in the mid-60s F. Nights, year-round, are much colder than daylight hours. Average temperatures are always about 10 degrees colder than London temperatures. Though there is very little snow in Scotland's major cities, snow and fog in the Highlands and high mountains are not uncommon and can often catch hikers by surprise.
Scotland's coast is so profoundly indented that its climate is almost island-like. Coast-to-coast at its narrowest point, between the Firth of Forth at Edinburgh, and the Firth of Clyde at Glasgow, it is only 25 miles wide. No one is ever more than about 45 miles from the sea. The influence of the Atlantic Ocean and its Gulf Stream to the west and the North Sea to the east moderate weather extremes but also create substantially different conditions east and west. The west of Scotland is wetter and slightly colder, with fewer sunny days than the east.
Scotland's Midge Seasons
Fans of outdoor pursuits in Scotland need to prepare for the country's plagues of midges, tiny biting insects that swarm in clouds so thick they sometimes look like fog. The females first emerge in May. They don't bite but are everywhere and are easy to inhale. Come June and the males, which do bite—a lot—hatch. Later in the year, if the spring has been unusually warm and humid, there is another wave of biting midges, mostly along the west coast, that hatch at the end of August or early September. Unfortunately, these months are also the most pleasant weatherwise. If you visit the beaches and the Highlands during midge seasons, bring plenty of insect repellent and avoid bare arms and legs. Campers should fit their tents with insect-proof netting.
The Seasons in Scotland
Regardless of what the calendar says, from a practical point of view, Scotland really has only two seasons, winter and summer. From mid-October through the end of April, the temperature variation is only about five degrees Fahrenheit. Though there may not be much snow—except in the mountains—wet, blustery weather can make all of these months bitterly cold. June, July, August, and sometimes September are the summer months with the best chance of milder, dryer temperatures and clearer skies. September is a kind of a toss-up. If it is dry, the heather-covered hills turn beautiful shades of gold and crisp, brisk temperatures prevail. But September is just as likely to be a wet, chilly month with damp, penetrating cold, even indoors.
The Different Regions of Scotland
Although the difference between the Highlands and the Lowlands sometimes seems more cultural than actual, Scotland is divided by a real geological division, the Highland Boundary Fault, that runs from Arran and Helensburgh, just west of Glasgow to Stonehaven, just south of Aberdeen on the east coast. The cities of Glasgow and Edinburgh and the parts of southern Scotland, known as the Borders, are in the Lowlands. Visitors come here for Scotland's major museums and festivals, its historic castles in Edinburgh and Stirling, for salmon fishing on the Tweed, golfing in St Andrews, and outdoor activities in Perthshire.
The weather across this region, coast to coast, is broadly similar with generally cloudy skies from October through May, windy and cold winters, and very little chance of snow or freezing temperatures. The windchill factor in the very hilly cities of the Lowlands makes winters seem much more bitterly cold than the mercury would suggest. The most significant difference is an east/west divide, with Glasgow and the west of this area having about twice as much rain as Edinburgh and the east. But this is mostly a matter of degree. In Glasgow, the U.K.'s rainiest city, average monthly rainfall during the wettest months—between September and January—is about 4.1 inches, and the daily chance of rain hovers around 50 percent. In Edinburgh, on the dryer east coast, the rainiest months are November through January, with the daily probability of precipitation a bit less than 40 percent. Average winter temperatures range from 34 to 43 degrees F, and average summer temperatures at the end of July/beginning of August range from 52 to 66 degrees F. The hours of daylight change dramatically with the seasons. In mid-winter, there are seven hours of daylight, while in mid-summer, the day lasts more than 17 and a half hours.
The Highlands and Islands
This is the designation usually given to the Western Highlands, the county of Argyll, Loch Lomond, and the Trossachs National Park, Islay, the Isle of Skye, the inner and outer Hebrides and many of Scotland's most beautiful lochs. Visitors flock here for the region's stark and dramatic mountain scenery, for its lochside cycling and hiking, for whisky tourism, and the many opportunities for sports and adventure in Glencoe and through Fort William.
This is a rainy region, being in the west and wetter part of Scotland. During the winter months of heaviest rainfall, as much as 4.7 inches a month can fall. But since the temperature rarely drops below 34 F in winter, there is little snow except on the mountain tops. Summer temperatures average about 65 F. The best chance of clear, dry weather for this area's outdoor activities in from the end of June to the end of August.
In the islands, the presence of the Gulf Stream moderates temperatures, so you can expect cool summers and moderate winters with the mercury rarely falling below 37 F. There is, however, a lot of rain—nearly 5 inches a month during the heaviest rainfall months of November to January. In summer there is plenty of daylight to enjoy the outdoors. On the longest day, in June, the sun rises at 4:26 a.m. and doesn't set until 10:17 p.m., giving about 17 hours and 50 minutes of daylight. That makes up for the short winter days, with mid-winter clocking up only six hours and 45 minutes of daylight
The enormous Cairngorm National Park, in central Scotland, is the country's most significant wilderness region and its coldest. Balmoral, the Queen's private vacation home, is located here, and the house and grounds are visitor attractions when the royal family is not in residence. It is also the center for Scotland's winter sports with its most popular and most reliable ski areas. While other regions, notably Ben Nevis and Glencoe in the Highlands, have ski areas, they are more likely to rely on snowmaking equipment than the ski areas of the Cairngorms. Winter temperatures here range from 30 F to 38 F with a much colder wind chill factor in the high mountains. The snowiest season lasts from the end of December through February, but snow remains in the highest peaks until well into the spring. During the summer months, in July, the temperature ranges from 49 to 62 degrees. It is cloudy more often than clear. Days are long in the summer, reaching nearly 18 hours of daylight in mid-summer. In December, on the other hand, there are only six hours and 40 minutes of daylight.
Winter in Scotland
Winter in Scotland lasts about nine months. From late September through the end of May, you can expect cold, wet weather punctuated by occasional bright, clear, and frigid days. Cloud cover holds heat closer to the ground, so when Scotland's skies are clear and starry at night, or bright and blue during the day, the temperatures will be the coldest. Because Scotland has a generally damp climate, the cold is penetrating and more uncomfortable than the temperature might indicate.
What to pack: Bring warm, waterproof outerwear, hats, gloves, and boots. Pack some fleece tops to layer on over long-sleeved T-shirts and sweaters if necessary. Make sure you have water-resistant shoes and plenty of dry socks if you plan to spend a lot of time out of doors. And bring warm sleepwear. Even though central heating and home insulation have improved dramatically in Scotland, the Scots like to keep their homes much cooler than most Americans are used to. Pack cardigans or light jackets to wear indoors. If you're planning a city break in Edinburgh, Glasgow or Dundee, you'll still want to pack wooly tights and a proper winter coat.
Summer in Scotland
Mid-June to mid-September are the warmest months in Scotland with the best chance of sunshine. Although the average high temperature throughout Scotland at this time of year is in the mid-60s, it is just an average. Record-breaking heatwaves, in line with the current climate extremes worldwide, are not unheard of. But nights can still be 10 to 15 degrees colder than days, so be prepared—and don't forget about the midges.
What to pack: Bring a raincoat or a waterproof poncho to layer over your backpack. Pack a quilted or fleece vest—what the British call a gilet. If you are going to be traveling in May, June, or early September, be sure to include lightweight, long-sleeved shirts and long trousers to protect against the midges. And buy some insect repellent designed explicitly for Scotland's midges. Camping and outdoor suppliers usually sell it. Bring sunscreen as well. The days are long, and the hard angle of the northern sun, mainly reflected off lochs, can be surprisingly intense. In terms of your general wardrobe, include layers that you can add on or remove to suit the changing weather conditions and your level of activity. It can just as quickly be hot as chilly.
Winter or summer, you can expect some rain when you are in Scotland. But it is also very windy—so foldable umbrellas have a pretty short lifespan. We'd recommend bringing waterproof outerwear and hats instead. It is easy to pick up an inexpensive umbrella after you arrive if you really need one.