SEASONS: Edinburgh has a four-season year, based on temperature and the vegetative cycle. Spring (mid-April through early June) is the season of lengthening days and diminishing frosts. It finds the trees leafing out, and the new annuals sprouting from the ground. Summer (early June through mid- September) is frost-free, with the vegetation in full foliage. Autumn (mid- September through mid-November) is brief, and brings shortening days and increasing frosts. Deciduous trees drop their leaves, and the annuals wither away. Winter (mid-November through mid-April) comes with short dark days, freezing temperatures, and snow. Trees stand with bare branches and vegetative growth is dormant until spring.
SUNNIEST MONTHS: May and June. This is when you can expect to get the sunniest weather of the year. Scotland is not known as a sunny land, and only 31% of the year's daylight hours will be sunny. This will range from a high of 35% in glorious May and June, to a low of 20% in gloomy December.
The long summer days are made even longer by abundant morning and evening twilight. You can count on an extra hour of twilight before sunrise, and an identical amount after sunset. This makes for short nights.
WARMEST MONTHS: July and August. During these months, afternoon temperatures range from downright crisp to warm (not hot), with the average being mild. Nights are generally cool and damp. The hottest temperature of the year will be around 78░, and will probably occur in late June or July.
Hardly ever will the nights be hot enough to require any sort of room- cooling. In fact, many visitors will welcome a morning fire in the grate before they toss back the quilts and step onto the cold floor.
COOLEST MONTHS: Late December through February. At this time of year, you can expect frosty mornings on almost half of the days. The afternoons are usually significantly warmer, however, with afternoon temperatures remaining below freezing only three or fours days each winter--usually during an outbreak of Arctic air. The coldest temperature of the year will be around 22░, and will probably occur in January.
Snowfalls are common enough during the winter months, but not as common as rain (including freezing rain). Consequently, the snow that does fall rarely stays on the ground for long--especially in the city center. Winter days in Edinburgh are short, dark, wet, windy, and generally miserable.
DRIEST MONTHS: March through May. Some 47% of the year's days will get no measurable precipitation; that is, they will get less than a hundredth of an inch. May will have 54% such dry days, whereas November and December will get only 42%. A "dry day" in the table, however, is one with less than a tenth of an inch--a more useful measure. It takes at least that much to wet the ground under the trees.
Much of the rain that falls is light, sometimes only a drizzle. It can persist for days, however, and although the totals are not impressive, it does keep things wet. The Scots simply put on their woolens and go about their business. Visitors are encouraged to do the same.
THINGS TO KNOW: Wool is the ideal material for Scottish weather. Good wool has the advantage of beading water on the outside while staying dry on the inside. When wet, it dries from the inside (skin side) out when subjected to body heat. Wet or dry, it maintains its loft and insulating abilities. Cotton, in contrast, dries from the outside in--leaving the layer next to the skin clammy the whole time. It collapses when wet, and retains little insulating ability. Canny visitors will wear wool outer garments.