Information on the Sierra de Gredos, Central
Spain
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CLIMATE Annual Rainfall Weather Overview The Sierra de Gredos enjoys a Continental variation of the Mediterranean climate in that winters are cold but summers are hot and there is very little rain. The summer temperatures are less extreme than those experienced on the plains but can still reach 30+ºC during the day. This makes cooling off in the mountain rivers and pools a welcome relief if walking, and means the days are warm enough to spend lazing by the riverbank picnicking or barbecueing. The evenings and mornings are pleasantly cool. The weather usually warms up about mid June and cools down sometime towards the end of September or early October. There may be snow still on the high peaks into June. Most of the weather comes from the South west and the result of this is that the Sierra de Bejar and the Southern side of the mountains have a higher average annual rainfall than the northern valley. Heaviest rainfall tends to be in Oct/Nov/Dec and March/April. The winter on the South side is relatively mild and the area from Arenas de San Pedro to Plasencia enjoys a micro-climate that allows the growth of more Mediterranean plants – oranges, palms and bouganvillia for example. There is rarely snow in the valley of the Tietar River and the area of La Vera, being approx. 400 metres above sea level. In the Northern valley the temperatures can drop quite low, the River Tormes being above 1200 metres above sea level. Throughout the colder months there are usually many clear, bright sunny days that bring the daytime temperatures up and make it very pleasant for walking and sightseeing. Snow usually arrives by November on the higher peaks and lasts above 1800 ms until into May/June. There are periods of snow in the villages along the main road, AV941, of the Northern Valley. This road is always kept clear as it is the main artery along the Gredos, as is the N502 road through Puerto del Pico from Córdoba to Ávila. Spring arrives later in the Northern Gredos valley, usually about May, when the meadows are full of wild flowers. Many of the slopes are carpeted with broom and the white broom is frequently seen. As there are a variety of trees (evergreen and deciduous oaks, poplar, alder, birch, pines etc.) in the Gredos the Autumn is a very beautiful time of the year with the leaves turning many different colours.
Comparisons of average annual rainfall in 3 areas of the Sierra de Gredos. Figures are given in litres per square metre. Hoyos del Espino: village in the Central Gredos nearest the Plataforma – Annual average 892 l/sq.m
Puerto del Pico is the main pass through the Central Gredos. - Annual average 1308 l/sq.m
Arenas del San Pedro is the main town on the South side of the mountains in the Tietar valley – Annual average 1554 l/sq.m
July and August are the most reliable months for weather in Gredos. The days are hot and sunny reaching temperatures in the low 30ºs C. The evenings are pleasantly warm. Occasionally there is a cooler spell in August. Very occasional thunderstorms. Walking on the South face of Gredos can be rather arduous in these months as the climbs are steep. Walking in North Gredos during July and August is fine - an early start is recommended. Definitely warm enough to want to cool off in some of those beautiful river pools. The rest of the year the weather is less reliable as is common in mountainous areas. April, May, June, Sept.& Oct. There can be spells of low cloud, mist, rain and cooler temperatures with the evenings and nights being cool. During these months there can also be spells of bright, sunny days and the tempertures will then rise to the 20ºs C, high 20’s/low 30’s in Sept and May, June. Jan., Feb., Nov. & Dec. These are the months when it is most likely to snow – above 1800 ms there will be snow and ice and, depending on the current weather conditions, this may occur at lower altitudes. Snow often lasts into June. Again the weather can be changeable but is somewhat more reliable than in the UK peak areas. There are often spells of sunny weather and again the temperatures rise and it is often warm enough to walk in T-shirts in the middle of the day (and in the snow!). The nights and mornings can be very cold with temperatures of -12ºC being recorded occasionally. We have decided not to include a table of monthly average temperatures as these cover all conditions in the month and don’t really provide useful information. Please bear in mind that these are guidelines only. Link to this week’s weather forecast here. This takes you straight to Ávila province Then select a village/town in the drop down list under "Seleccione municipio". Selecting Hoyos del Espino will give you the best forecast for the Regional Park and Central Gredos (North side) GEOLOGY The Gredos mountains are formed mainly of granite, a metamorphic rock made up of quartz, mica and feldspar. This was formed over app. 300 million years and over 400 million years ago in the Paleozoic era or First Age, when the marine sediment from the Tethys ocean, which covered the Iberian Peninsular, built up heat and pressure and metamorphosised at its heart to produce gneiss, slate and schist. At the end of the First Age, in the tectonic processes known as the Hercynian uplift about 250 million years ago, this metamorphic rock was pushed up from about 600 ms to form the beginnings of the main mountain ranges. The sediment eroded during the relatively calm Mesozoic or Second era, until the geologically recent tectonic processes of the Alpine shift, about 25 million years ago, created the mountain ranges of the Himalayas and the Alps amongst others, including the Gredos, during the Cenozoic or Third era. The sedimentary layers formed the Mesetas. To the South of the Gredos the blocks sank to form the much lower valley floor of the Tietar. There was then a general balancing towards the West causing the flow of the large rivers, Tajo and Duero, to the Atlantic and Portugal. The main passes of Puerto del Pico and Tornavacas were formed by large transverse faults. Some vertical fracturing has produced needlelike rock formations (agujas in Spanish) and knife-edged ridges (cuchillares) but otherwise the granite has been smoothed by erosion. About 2 million years ago the depression of the River Tormes to the North occurred as a result of the tectonic movements and the balancing towards the West. In the last period of the Ice Age the Gredos was subjected to glaciation which ended about 10,000 years ago. The glaciers altered the river basins and valleys from their typical V shape to the shape of a U leaving cirques/corries at the head and glacial lakes. Between Puerto del Pico and Tornavacas there were 41 glaciars, the largest being what we now know as the Circo de Gredos with its lake, Laguna Grande.
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