You are currently viewing Best Packing List for Your Thermal Comfort when Watching the Aurora

When you visit Alaska in winter to watch the aurora, read this post to know when to come, what potentail weather conditions and thermal discomfort to expect, what causes the discomfort and what to pack for comfort for aurora watching.

  1. Prologue
  2. Fairbanks Is a Favorite Destination for Aurora Watching
  3. What to Pack for Comfort for Aurora Watching
  4. What to Pack for Comfort for Aurora Watching Is Not about Style
  5. Weather-wise, Aurora Watching Conditions Are Best in March
  6. Sun Shine at the Top of the Atmosphere and the Earth’s Surface
  7. How Do the Weather Conditions Affect Your Thermal Comfort?
  8. In Clear Nights, Temperature Seems to Be in Free Fall
  9. Sun Shine at the Top of the Atmosphere and the Earth’s Surface
  10. Energy Exchange between Your Body and the Ambient Air Causes Thermal Discomfort
  11. Discomfort due to Conduction
  12. The Role of Humidity for Thermal Comfort
  13. Insulation Is Important for Thermal Comfort
  14. Fabrics also Have Moisture Properties
  15. Wicking and Layering Is Key
  16. How to Stay Comfortable when Visiting the Interior
  17. Take Home Message on What to Pack for Comfort for Aurora Watching
  18. Further Readings
  19. References



Last week, a friend of mine stopped by my office to drop a dress off that I had borrowed her for an outreach project. “What have you been up to lately?” I asked. She said that she and her students were at the airport this week greeting the first Chinese charter flight of this aurora watching season. Her Chinese class sang a Chinese welcome song. “How exciting” I responded.


Fairbanks Is a Favorite Destination for Aurora Watching

Alaska is not only a great land to visit under the midnight sun, but also in winter for aurora watching. The aurora attracts many tourists from Taiwan and Japan every winter. The aurora travel packages of some companies include outerwear. Therefore, you can identify the Princess aurora tourists from Japan in town by their orange long down parkas with fur hoods. However, what else do you need for aurora watching when you are from a warmer region than Alaska?

What to Pack for Comfort for Aurora Watching

Here is a list of essential items to pack and wear for aurora watching.

  1. Underwear – long thermal underwear, in plain English long johns. They are an essential part of the layering to create the right insulation to enjoy watching the aurora at -20F (-28.9oC). Underneath the long johns wear your underpants, bra (unless you are a guy), and undershirt.

    Tip: The breast enhancer bras provide greater insulation than a lacy bra.

  2. Alaska jeans – these are jeans with 16 oz weight and a flannel lining inside.
  3. A wool sweater.
  4. Socks. Go for wool socks as they absorb sweat without feeling wet and cold.
  5. Bunny boots are the gold standard, but hard to get outside of Alaska (and even in Alaska). Sorel boots or similar, but suitable for -40F (-40oC) will do too. Read the description. Buy them with wool socks on. Make sure they do not squeeze your feet. Any squeezing leads to cold feet, i.e. go a size up. Read more on avoiding cold feet.
  6. Thermal over-pants or a thermal skirt to keep the knees and thighs warm.
  7. The down parka with hood should cover you bum and should fit loose, not tight. You don’t want to squeeze the air layers between the layers. Air is a great insulator.
  8. Silk lined gloves under a pair of shearling mittens. They should be long enough that they overlap with the sleeves of your parka so you don’t have any cold bridges. Read more on cold gaps in clothing.
  9. A scarf. A qiviut scarf made from the under-wool of the musk ox is the best.
  10. A qiviut hat, best in trapper style to cover your ears and head. Wear the ear pieces down. Oh, did I mention that chandeliers or long metal earrings will get cold and may stick (read freeze) to your skin at 40 below?
  11. Swimwear to relax and warm up in one of the off the tourist path hot springs in Alaska.
  12. A face mask. Be careful! Have the face mask in your checked-in baggage! Don’t have a mask in your carry-on baggage! Some countries forbid wearing and/or owning face masks. As a result, you may consider buying a face mask in Alaska and leaving it there when they are not allowed in your homeland.


What to Pack for Comfort for Aurora Watching Is Not about Style

Yes, in this outfit, even a size 2 person looks like a dumpling. But you still can look stylish in outerwear at 40 below when you color-coordinate. Think of this aurora watching outfit as a casual vacation outfit that insulates at the same time. When you arrange your own travel, read what to look for when buying a down coat so you won’t waste your money on a coat that is useless for Fairbanks climate conditions.


The Aurora Is only Visible during Darkness on Clear Sky Days

During summer, you can’t watch the aurora despite it is out there. You only recognize it by disturbed cell phone communication. Therefore, when you make Fairbanks your destination for aurora watching, you have to come after mid August and before May to have a chance. The best month to watch the aurora in Fairbanks is March. In Interior Alaska, March is the driest month with respect to precipitation and cloudiness on climate average, because it the start of the drought season. Therefore, the likelihood that the sky is clear is the highest. August is the rain season. Consequently, your chances for clear sky are low.


Other Factors Affecting the Aurora

The occurance of a strong aurora depends on the activity of the Sun. The higher it is the stronger and more colorful the aurora becomes. Read more on the colors of the aurora.  Unfortunately, this activity is a function of the about 11 years sun spot cycle.


Weather Conditions and Climate Mean Differ Strongly

According to the World Meteorological Organization, a climate mean is the average over the weather conditions over several (typically 30) years. Of course, in individual years, the weather deviates from the 30-years average. In other words, you may end up visiting in a March that is much more cloudy than on average. Under these circumstances, your chances to see the aurora are lower than on average.


long term daily means of temperature in Fairbanks in March
Daily mean near-surface air temperature in Fairbanks in March averaged over 1988 to 2016. The gaps indicate that not 30 years of data were available for these days. The color coding refers to the thermal comfort accoding to the table in this post.


daily mean temperature and thermal comfort in Fairbanks in 2015
Daily mean near-surface air temperature (T) and universal temperature comfort index (UTCI; temperature how we feel it) in Fairbanks in 2015. The color coding is explained in the next section.


How Do the Weather Conditions Affect Your Thermal Comfort?

When it’s moist and/or windy while cold you feel thermal stress, not only because it is cold. Various stress categories exist (see table below).


table of thermal comfort dependent on air temperature in C and F
Table of thermal stress categories in dependence of the Universal Thermal Comfort Index (UTCI) given in degree Celsius (left) and Fahrenheit (right). The UTCI considers the impact of wind, relative humidity, insolation and temperature as well as the human metabolism under the assumption that the person is approriately dressed for the actual weather conditions. Note that this color coding of the thermal stress categories is used in the figures shown in this post.


In Clear Nights, Temperature Seems to Be in Free Fall

Daily minimum and maximum temperatures, which are the lowest and highest temperatures in the figures below) vary also from their long-term mean. For all these reasons, packing for the daily climate mean temperature is by no means sufficient for protection from frostbite and/or hypothermia. Add wind to the mix, then you feel even colder than it actually is due to wind chill. If it is also humid, the thermal comfort is even worse.


fairbanks diurnal course of temperature
Hourly mean temperature in Fairbanks on March 29, 2016 as an example how temperature and the UTCI may vary during the diurnal course and differ from the climate daily mean value. The colors indicate the thermal stress according to the table above.


diurnal cycle of hourly mean temperature temperature in Fairbanks
Hourly mean temperature in Fairbanks on March 6, 2016.The color coding refers to the thermal comfort accoding to the table above. Compare the conditions to those on March 2016 as an example how temperatures may differ in the diurnal course among days of the same month.


hourly temperatures on an extremely cold day to understand what to pack for comfort for aurora watching
Hourly mean temperature in Fairbanks on March 13, 2007. The color coding refers to the thermal stress categories shown in the above table. This examples show that the UTCI can be lower or higher than the actual temperature as well as identical.


Sun Shine at the Top of the Atmosphere and the Earth’s Surface

Energy from Sun radiates thru space to the Earth. At the top of the atmosphere, incoming solar radiation differs by latitude, season, time of the day. At the Earth surface, this incoming solar radiation may be less due to cloudiness, absorbing gases in the atmosphere and air pollution.

Radiation transfers heat by electromagnetic waves. The diagram below illustrates that insolation from the Sun is the largest in the Arctic and Antarctic in boreal and Austral summer, respectively. It is lowest in the respective winters of each hemisphere. The figure also reveals that the southern hemisphere receives more


solar radiation input over a year at various latitudes to show when auror watching is possible
Mean solar radiation (also known as insolation or shortwave radiation and called sun shine by most people) as a function of latitude and day of the year (DoY). Fairbanks is at 64.8378N


Energy Exchange between Your Body and the Ambient Air Causes Thermal Discomfort

According to Planck’s law, every body including the air radiates at its own temperature. Cold bodies radiate with lower energy than hot bodies. This means the energy flows from the higher to the lower energy, or in other words, from the warm to the cold body. Thus, clothes or exposed skin loose energy by radiation when they are warmer than the ambient air.

There will be no loss by radiation when your clothes’ and the air have the same temperature (see plot below). However, even when you dressed appropriately, your body will loose heat when the environment is colder than your body temperature. The bigger the difference between the surface temperature of your outerwear and the environment is, the higher the loss of radiation energy will be.

thermal behavior of clothes worn for aurora watching
The gain or loss of radiation energy is zero where the environment and clothes have the same temperature. Loss of heat occurs left of this point, gain on the right. Loss means that the clothes’ temperature decreases, gain means it increases. A gray and perfect black clothes are shown.


Discomfort due to Conduction

You also loose body heat due to conduction, which refers to the transfer of heat by molecules. For example, heat from your feet is transferred to the sole of your boots to the frigid cold soil. Consequently, your feet loose energy that your body has to compensate for by means of chemical energy (food).

Furthermore, there is a huge temperature gradient between your skin (98F, 37.5oC) and the ambient air (see graphs for air temperatures above). The skin increases the air temperature in the vicinity of the skin. This slightly warmer, buoyant near-skin air rises. Thereby, it transports heat away from your skin. This process is called convection. When it is also windy, the wind transports the slightly warmed air away too. This means that under windy conditions, your skin’s energy loss due to convection will accelerate.


The Role of humidity for Thermal Comfort

High humidity can not only make you feel uncomfortable at high, but also at low temperatures. Air feels colder than it is under cool conditions with high relative humidity. Being in the shadow or in the sun makes a difference in thermal comfort. Walking causes movement and mixing in the air layers between your clothes or your skin and the first layer. Thus, the heat exchange is higher than when just standing.

Researchers used manekins warmed to skin temperature and various artifical “sweating methods on them” and equipet the various clothes layers with temperature sensors and/or measured the heat they had to replace to hold the manekins’ temperature. Researchers also asked appropriately dressed people about their thermal comfort. Using these data empirical relationships have been derived that determine a to determine the universal thermal comfort index (UTCI) that is expressed as a temperature. I used this empirical model to calculate the UTCI that measures how we feel the temperature under the respective environmental conditions. Depending on the environmental conditions the environment can feel warmer or colder than it actually is (see temperature and UTCI plots in this post).


Insulation Is Important for Thermal Comfort

Clothing hinders energy loss. Fabrics with low conduction coefficient are great for creation of a good body insulation. Thin air layers are best as air is a bad thermal conductor. Consequently, layering is key to create appropriate insulation to stay outside for several hours when watching the aurora. Wherever the fabric is in direct contact with your body and/or the environment, conduction takes place. A down coat that has a water resistant outer coating is a great insulator.


insulation characteristics of clothes to pack for comfort for aurora watching
Thermal properties of various fabrics including air. In case of air, the lower thermal conduction coefficient is valid for thin air layers, while the large one corresponds to a thick layer wherein convection and movement occurs. The lower the value the better the insulation.



Fabrics also Have Moisture Properties

Sweating serves to regulate body temperature by evaporation that causes cooling. In cold climate, evaporative cooling is unwanted. As a result, you will have to choose a wicking fabric closest to your body to avoid that the fabric gets wet.


Wicking and Layering Is Key

Modal, rayon, viscose, tencel, lyocell, and bamboo take up sweat. Once they are wet, insulation is zero! Thus, these materials are not a great choice for thermal comfort at temperatures in the the negative double digits. On the contrary, merino wool can take up a lot of moisture without feeling wet.


How to Stay Comfortable when Visiting the Interior

Wool socks are a must! Wear two pairs for extra insulation and always buy your winter boots a size larger than your summer shoes. Recall squeezing your feet in means you have contact between the feet, the socks, and boots and hence conduction of heat to the environment.

Go for silk or polypropylene long underwear. Pile on layers of polar fleece or wool for insulation. The outermost layer should protect against wind and moisture from outside, i.e. melting snow or under warmer conditions rain.

Adjustable openings avoid cold bridges where cold air can enter and mix with the air between your layers. A high percentage of body heat is lost via the head followed by the extremities. Thus, a hat, scarf, and gloves are must-haves. In March, the Sun is still low in the sky. Sunglasses are needed during the days because of the refection of the sun beams on snow and icy roads. The snow acts like a mirror which means that sunscreen with a high SPF is needed when you do sightseeing during the day. Since temperatures may go above the freezing point during the day, waterproof shoes with thick insulating soles are needed. Avoid rubber boots as the thermal conductivity of rubber is high.


Take Home Message on What to Pack for Comfort for Aurora Watching

Together these facts mean that how we feel our environment when dressed appropriately depends on energy exchange (wind, radiation, humidity, etc.), and our activity. Air can feel warmer/colder than its actual temperature. What to pack for comfort for aurora watching are clothing in materials with low conductivity to reduce convection and radiation loss. The clothing in the right fabrics must be suitable for layering to create thin air layers. Thin air layers namely are perfect for insulation meaning that you can prolong the time you can stay outside in comfort. Layering is key, style is optional.

P.S. At 40 below, batteries freeze. Thus, keep your camera warm. More on taking photos in the Arctic.


Further Readings

You can find a video of my talk about the physics of clothes – what Alaska’s climate means for body heat exchange at the link. You may also be interested in reading what you need to increase safety when traveling in Alaska. There are also lookbooks for each month that contain outfit inspirations for various temperature ranges for work and play. Take into account that people adapt to the weather of their climate region. This means when you live in a region with warm or hot weather you might dress with an additional layer.



Mölders, N., 2019: Outdoor Universal Thermal Comfort Index Climatology for Alaska. Atmospheric and Climate Sciences9, 558-582. doi: 10.4236/acs.2019.94036.

Shulski, M. and Wendler, G. 2007: The Climate of Alaska. University of Alaska Press, Fairbanks. 216 p.

Photos: G. Kramm
Graphics: N. Mölders

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