Historical Weather For 1971 in Tanana, Alaska, USA

Location

This report describes the historical weather record at the Ralph M. Calhoun Memorial Airport (Tanana, Alaska, United States) during 1971. This station has records back to July 1948.

Tanana, Alaska has a humid subarctic continental climate with cool summers and no dry season. The area within 25 mi of this station is covered by forests (94%) and lakes and rivers (4%)

Calendar

Daylight saving time (DST) was observed at Tanana, Alaska during 1971. There were two time changes during 1971:

  • DST started on Sunday April 25, 1971 at 3:00 am, from -10:00 (GMT-10) to -09:00 (GMT-9).
  • DST ended on Sunday October 31, 1971 at 1:00 am, from -09:00 (GMT-9) to -10:00 (GMT-10).

1971 was not a leap year, so it has 365 days and no February 29th. The first leap year before 1971 was 1968 and the first after was 1972.

The summer and winter solstices and the spring and fall equinoxes mark the passing of the seasons. They fall on nearly the same day each year, with differences of a day or two depending on the year. In 1971 they occurred on:

Spring Equinox Sunday, 21 March 1971.
Summer Solstice Tuesday, 22 June 1971.
Fall Equinox Thursday, 23 September 1971.
Winter Solstice Wednesday, 22 December 1971.

Temperature

The hottest day of 1971 was February 21, with a high temperature of 22°F. For reference, on that day the average high temperature is 8°F and the high temperature exceeds 25°F only one day in ten. The hottest month of 1971 was February with an average daily high temperature of -5°F.

Relative to the average, the hottest day was January 4. The high temperature that day was 13°F, compared to the average of -3°F, a difference of 16°F. In relative terms the warmest month was February, with an average high temperature of -5°F, compared to an typical value of 5°F.

The month of February had the largest fraction of warmer than average days with 21% days with higher than average high temperatures.

Temperature

The daily low (blue) and high (red) temperature during 1971 with the area between them shaded gray and superimposed over the corresponding averages (thick lines), and with percentile bands (inner band from 25th to 75th percentile, outer band from 10th to 90th percentile). The bar at the top of the graph is red where both the daily high and low are above average, blue where they are both below average, and white otherwise.

The coldest day of 1971 was January 24, with a low temperature of -61°F. For reference, on that day the average low temperature is -14°F and the low temperature drops below -44°F only one day in ten. The coldest month of 1971 was March with an average daily low temperature of -36°F.

Relative to the average, the coldest day was February 24. The low temperature that day was -61°F, compared to the average of -9°F, a difference of 52°F. In relative terms the coldest month was March, with an average low temperature of -36°F, compared to an typical value of -2°F.

The longest cold spell was from January 12 to February 6, constituting 26 consecutive days with cooler than average low temperatures. The month of January had the largest fraction of cooler than average days with 84% days with lower than average low temperatures.

The longest freezing spell was from January 1 to March 11, constituting 70 consecutive days with temperatures strictly below freezing.

Hourly Temperature Bands

The full year of hourly temperature reports with the days of the year on the horizontal and the hours of the day on the vertical. The hourly temperature measurement is color coded into meaningful temperature bands: frigid is purple (below 15°F), freezing is blue (15°F to 32°F), cold is dark green (32°F to 50°F), cool is light green (50°F to 65°F), comfortable is yellow (65°F to 75°F), warm is light red (75°F to 85°F), hot is medium red (85°F to 100°F), sweltering is dark red (above 100°F), and missing data is pink.

Clouds

The clearest month of 1971 was January, with 39% of days being more clear than cloudy. The longest spell of clear weather was from January 15 to January 19, constituting 5 consecutive days that were clearer than they were cloudy.

Cloud Coverage

The fraction of time spent in each of the five sky cover categories over the course of 1971 on a daily basis. From top (most blue) to bottom (most gray), the categories are clear, mostly clear, partly cloudy, mostly cloudy, and overcast. Pink indicates missing data. Outside of the United States clear skies are often reported ambiguously, leading them to be lumped in with the missing data. The bar at the top of the graph is gray if the sky was cloudy or mostly cloudy for more than half the day, blue if it is clear or mostly clear for more than half the day, and blue-gray otherwise.

The cloudiest month of 1971 was February, with 50% of days being more cloudy than clear. The longest spell of cloudy weather was from February 5 to February 11, constituting 7 consecutive days that were cloudier than they were clear.

Hourly Cloud Coverage

The full year of hourly cloud coverage reports with the days of the year on the horizontal and the hours of the day on the vertical. The sky cover is color coded: from most blue to most gray, the categories are clear, mostly clear, partly cloudy, mostly cloudy, and overcast. Pink indicates missing data. Outside of the United States clear skies are often reported ambiguously, leading them to be lumped in with the missing data.

Precipitation

This station provides hourly reports of significant weather events at and around the station, but does not report the quantity of precipitation at the station itself. This is common for weather stations located outside of the United States, and for a small subset of stations in the United States that are located at lesser used and smaller airports.

Present Weather Reports

This station reports when significant weather events (including precipitation) are visually observed at or near the station. Such events do not always correspond to measured quantities of liquid equivalent precipitation, such as when the event is near by not at the station, or in the case of solid precipitation that does not melt in the collection basin.

The day in 1971 with the most precipitation observations was January 5. There were 5 hourly weather reports that day (out of a maximum of 24) in which some form of precipitation was observated at or near the station. The month with the most precipitation observations was February, with 37 hourly present weather reports involving some form of precipitation.

Precipitation Reports

The daily number of hourly observed precipitation reports during 1971, color coded according to precipitation type, and stacked in order of severity. From the bottom up, the categories are thunderstorms (orange); heavy, moderate, and light snow (dark to light blue); heavy, moderate, and light rain (dark to light green); and drizzle (lightest green). Not all categories are necessarily present in this particular graph. The faint shaded areas indicate climate normals. The bar at the top of the graph is green if any precipitation was observed that day and white otherwise.

As determined by the present weather reports, the longest dry spell was from March 11 to December 31, constituting 296 consecutive days with no observed precipitation. The months April, May, June, July, August, September, October, November, and December were completely without observed precipitation.

The month with the largest fraction of days with at least some observed precipitation was February, with 46% of days reporting some observed precipitation.

Hourly Weather Reports

The full year of hourly present weather reports with the days of the year on the horizontal and the hours of the day on the vertical. The color-coded categories are thunderstorms (orange); heavy, moderate, and light snow (dark to light blue); heavy, moderate, and light rain (dark to light green); drizzle (lightest green); freezing rain and sleet (light and dark cyan); snow grains (lightest blue); hail (red); fog (gray); and haze (brownish gray).

Liquid Precipitation Reports

In this section we consider only those weather reports that indicate liquid precipitation. For the purposes of this analysis, we include thunderstorms even though some thunderstorms are not accompanied by liquid precipitation.

The month of 1971 with the largest number of those reports was January, with a total of 0 reports. The day with the largest number of those reports was January 1, with a total of 0 reports.

Liquid Precipitation Reports

The daily number of hourly observed liquid precipitation reports (including thunderstorms) during 1971, with climate normals (faint shaded areas). The bar at the top of the graph is green if any liquid precipitation was observed that day and white otherwise.

Snow

This station reports when snow is observed falling but does not report the quantity of snow that has fallen or the depth of snow on the ground.

Reports

In this section we consider hourly weather reports that contain an observation of falling snow. These reports do not necessarily correspond to accumulation.

The first reported snow fall in 1971 was on January 1; the last was on March 10. The month of 1971 with the largest number of those reports was February, with a total of 37 reports. The day with the largest number of those reports was January 5, with a total of 5 reports.

Snow Reports

The daily number of hourly observed snow reports during 1971, with climate normals (faint shaded areas). The bar at the top of the graph is blue if there was snow fall observed that day and white otherwise.

Humidity

Humidity is an important factor in determining how weather conditions feel to a person experiencing them. Hot and humid days feel even hotter than hot and dry days because the high level of water content in humid air discourages the evaporation of sweat from a person's skin.

When reading the graph below, keep in mind that the hottest part of the day tends to be the least humid, so the daily low (brown) traces are more relevant for understanding daytime comfort than the daily high (blue) traces, which typically occur during the night. Applying that observation, the least humid month of 1971 was March with an average daily low humidity of 50%, and the most humid month was January with an average daily low humidity of 69%.

But it is important to keep in mind that humidity does not tell the whole picture and the dew point is often a better measure of how comfortable a person will find a given set of weather conditions. Please see the next section for continued discussion of this point.

Humidity

The daily low (brown) and high (blue) relative humidity during 1971 with the area between them shaded gray and superimposed over the corresponding averages (thick lines), and with percentile bands (inner band from 25th to 75th percentile, outer band from 10th to 90th percentile).

Dew Point

Dew point is the temperature below which water vapor will condense into liquid water. It is therefore also related to the rate of evaporation of liquid water. Since the evaporation of sweat is an important cooling mechanism for the human body, the dew point is an important measurement for understanding how dry, comfortable, or humid a given set of weather conditions will feel.

Generally speaking, dew points below 50°F will feel a bit dry to some people, but comfortable to people accustomed to dry conditions; dew points from 50°F to 68°F are fairly comfortable to most people, and dew points above 68°F are increasingly uncomfortable, becoming oppressive around 77°F.

To take some examples, and basing our categorization on the daily high dew point in 1971, January had 28 dry days, no comfortable days, and no humid days; April had no dry days, no comfortable days, and no humid days; July had no dry days, no comfortable days, and no humid days; and October had no dry days, no comfortable days, and no humid days.

Dew Point

The daily low (blue) and high (red) dew point during 1971 with the area between them shaded gray and superimposed over the corresponding averages (thick lines), and with percentile bands (inner band from 25th to 75th percentile, outer band from 10th to 90th percentile).

Wind

The highest sustained wind speed was 25 mph, occurring on February 10; the highest daily mean wind speed was 17 mph (February 9);

The windiest month was February, with an average wind speed of 8 mph. The least windy month was March, with an average wind speed of 5 mph.

Wind Speed

The daily low and high wind speed (light gray area) and the maximum daily wind gust speed (tiny blue dashes).

Other Measurements

This station did not reliably report the visibility during 1971.

Cloud Ceiling

This station did not reliably report the cloud ceiling during 1971.