The Pacific coast, a rainy oceanic climate
From the Aleutian Islands peninsula to the southeast coast, i.e. the entire Gulf of Alaska from Anchorage to Ketchikan, the climate is cool oceanic. The region has a low annual temperature range and abundant precipitation throughout the year, but with significant peaks during winter snowfalls. Summer is often foggy with frequent and rapid weather changes. The average temperature in Anchorage in July is 15°C. This is due to the proximity of the ocean but also to the passage of the warm Kouro Shivo current which comes from Japan: thus the sea air is warmed. The evaporation of water will form a humid air which, driven by the winds over the land, will collide with the coastal mountain ranges. Barred by the mountains, it turns into precipitation, rain or snow depending on the season. In this area, the climatic contrasts are enormous. Thus Homer and Seward, two cities on the Kenai Peninsula not far from Anchorage, and Montague Island located opposite Seward, have very different rainfall patterns which can be explained by their orientation in relation to the coast. The city of Homer receives 600 mm of water per year while Seward receives 1,700 mm; Montague Island boasts a record of 8,500 mm over a year, which is four times what falls on the Amazon!
The Aleutian Islands, cold and windy
They delimit the Gulf of Alaska on one side, in the Pacific Ocean, and the Bering Strait on the other, in the eponymous sea facing Siberian Russia. Here the average altitude is relatively low. On the other hand, the fog is almost permanent and there are only 36 days of sunshine on average per year. Thus with relatively mild temperatures and high humidity, the vegetation is very dense. It is the kingdom of the forest, with large trees and especially spruces. The undergrowth is a carpet of moss and lush ferns. Only the windy areas have relatively little vegetation. Few visitors venture on these very wild islands nevertheless.
The interior: snowy in winter, sunny in summer
It is a continental climate of Siberian type which reigns on the interior of Alaska, particularly in Fairbanks and in the Denali National Park, the regions most visited by the tourists. The annual thermal amplitudes are important with a very cold winter and less precipitations than in the rest of the state, because this region is sheltered from the maritime influence by the mountain ranges. The city of Fairbanks regularly sees the thermometer drop below -45°C in winter and the average temperature in December, January and February is around -20°C! On the other hand, the average annual precipitation is 350 mm, lower than on the coasts.
The extreme north, a polar climate
Beyond the Arctic Circle, the climate is almost permanently cold, with occasional strong winds, but with little precipitation. Two zones can be distinguished. The first is the Brooks Range with precipitation of about 200 to 300 mm per year; the second is a plain further north which, with 100 mm of rain per year, is drier despite its proximity to the Arctic Ocean. As it is frozen for much of the year, it gives off little moisture and consequently little rain.
On the other hand, temperatures are generally milder than in the Brooks Range. Be careful, though, because the average annual temperature in Barrow is -14°C! In July, the city experiences average temperatures of 3°C (beautiful sunny days exist), while the thermometer remains pointed at -30°C in winter; and up to -60°C at Prospect Creek Camp. It is therefore during the three mild months that you should plan your stay in this region, with as a basic element in your travel bag a good rain gear and warm and light clothes, because in the same day the temperature differences can be important.
The midnight sun, a polar phenomenon
Some phenomena relative to the latitudes of Alaska are particularly original. Thus the midnight sun causes an inequality between the day-night duration which is not always easy to live with. Thus, during the summer solstice, on June 21, the daytime is at its peak with, for example, 19 hours of daylight in Anchorage and a night that is in fact only a weak half-light. This is a particularly festive event in the city. On the other hand, when you are in Barrow, this date means nothing to the inhabitants. Here, on May 10, the sun rises and does not set until the beginning of August, which is more than 80 days without night! Conversely, when winter approaches, night replaces day and the 19 hours of daylight in Anchorage, in summer, are transformed into 19 hours of night. The same is true for Barrow where the night begins around November 18th and ends on January 24th... This is not without consequences on the psyche of the inhabitants. Thus, cabin fever, which could be translated as "interior fever", affects a good number of inhabitants and manifests itself by a depressive feeling, faced with the cold, the night and the confinement during the winter (Alaska has the highest suicide rate in the United States). It is also a period of inactivity that is on average fourteen times higher than in the rest of the country. Normann Mailer wrote about Alaska that it was the northern terminus of neurosis.
The magic of the northern lights
Who has never dreamed of witnessing the light show offered by the northern lights? The Tlingit Indians believe that the northern lights were the welcome to the sky of a fallen warrior. These atmospheric phenomena are not as rare as we think. In addition to this poetic explanation and belief, there is a scientific explanation for this phenomenon. The electrons and protons projected by the sun constitute a solar wind and a flow of particles that enter the earth's sphere at about 50,000 km/h, causing them to be diffracted towards the poles. These particles are usually blocked by the Earth's natural magnetic field. But at the poles, this magnetic field is less active, allowing the electrified particles to collide with the atoms of the upper atmosphere (oxygen, nitrogen, hydrogen...).
When they penetrate the upper layers of the atmosphere between 100 and 200 km in altitude, they collide with helium and hydrogen atoms. The shock thus produced releases photons, which emit light and the magic happens: these are the famous aurora borealis! The shapes are changing and irregular like draperies with yellow, red, green, blue or violet colors. Some regions have more intense auroras than others. Like in Fairbanks: with a latitude of 64.8561, the city is placed on the auroral oval which encircles the North Pole and constitutes the ideal zone to observe these luminous phenomena. At this latitude, it is possible to see up to 240 of them per year! For the aurora hunters, a perfect website gives day by day the mapped weather of this unique magnetic phenomenon, dedicated to the intensity of the aurora magnetic ring in Fairbanks (www.gi.alaska.edu/AuroraForecast). The closer the activity level is to 9 (provided the sky is clear), the more likely you are to see beautiful auroras. However, from April 21 to August 21, the daylight is too bright, even in the middle of the night, to have a chance to see an aurora borealis, because of the summer equinox on June 21, which offers an increasingly intense midnight sun as you move towards the North Pole. Try your luck before or after, but be aware that in the middle of winter, the snowy sky prevents you from seeing the aurora borealis. The best nights are the result of equations between the season (not too much daylight but also moonlight), the weather (no clouds) and a strong magnetic activity. November-December and March-April are particularly good seasons to try your luck. We advise you to plan your itinerary in the north only at the last moment, depending on the weather and magnetic conditions, and to juggle your stay in Denali National Park (where the aurora can also be observed). You should know that once in Fairbanks, you will have to drive between 1 hour and 1h30 to get away from the city lights and observe the famous Northern Lights at night.
Seasonality linked to the climate
Those who love extreme conditions will certainly appreciate the winter season, when the snow spreads as far as the eye can see and in abundance on the Alaskan reliefs: skiing, skating on the frozen lakes, snowshoeing, snowmobile and dog sled races... But above all: watching the Northern Lights! Temperatures can drop to -35°C in January in Fairbanks, so you need to be well equipped. The best time to go to Alaska is between the end of May and the end of September, the summer being concentrated in July and August. The weather is then relatively mild (between 10 and 20°C in July) even if snow and cold can still occur, and mosquitoes are numerous and voracious! Some places or activities are not accessible before the end of June because of the snow. Bear watching takes place from the end of May to the end of September. During the good season, it is an opportunity to camp (the cheapest way to visit Alaska), hike, go bear fishing, kayak, boat to see the collapsing glaciers, orcas, whales, etc. sail in the fjords.
