This report describes the historical weather record at the Aitkin Municipal Airport (Steve Kurtz Field) (Aitkin, Minnesota, United States) during 2012. This station has records back to August 1992.

Aitkin, Minnesota has a humid continental climate with warm summers and no dry season. The area within 25 mi of this station is covered by croplands (87%) and lakes and rivers (12%)

Daylight saving time (DST) was observed at Aitkin, Minnesota during 2012. There were two time changes during 2012:

2012 was a leap year and thus has 366 days rather than the normal 365. Leap years occur every fourth year and the extra day is always February 29th. In 2012 February 29th falls on a Wednesday.

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 2012 they occurred on:

The hottest day of 2012 was July 2, with a high temperature of 91°F. For reference, on that day the average high temperature is 77°F and the high temperature exceeds 85°F only one day in ten. The hottest month of 2012 was July with an average daily high temperature of 83°F.

Relative to the average, the hottest day was March 18. The high temperature that day was 75°F, compared to the average of 39°F, a difference of 36°F. In relative terms the warmest month was March, with an average high temperature of 52°F, compared to an typical value of 38°F.

The longest warm spell was from August 21 to September 7, constituting 18 consecutive days with warmer than average high temperatures. The month of July had the largest fraction of warmer than average days with 84% days with higher than average high temperatures.

Temperature

The daily low (blue) and high (red) temperature during 2012 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 2012 was January 19, with a low temperature of -18°F. For reference, on that day the average low temperature is 0°F and the low temperature drops below -18°F only one day in ten. The coldest month of 2012 was December with an average daily low temperature of 8°F.

Relative to the average, the coldest day was January 19. The low temperature that day was -18°F, compared to the average of 0°F, a difference of 19°F. In relative terms the coldest month was September, with an average low temperature of 41°F, compared to an typical value of 45°F.

The longest cold spell was from September 21 to October 16, constituting 26 consecutive days with cooler than average low temperatures. The month of September had the largest fraction of cooler than average days with 73% days with lower than average low temperatures.

The longest freezing spell was from December 17 to December 31, constituting 15 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.

The clearest month of 2012 was August, with 77% of days being more clear than cloudy. The longest spell of clear weather was from August 26 to September 7, constituting 13 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 2012 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 2012 was October, with 61% of days being more cloudy than clear. The longest spell of cloudy weather was from October 22 to October 30, constituting 9 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.

This station reports the quantity of liquid precipitation but not observations of weather events in the area. For this reason, this section will only discuss the quantity of precipitation and not its type.

Liquid Equivalent Quantity

The day with the largest quantity of precipitation was June 20. That day saw 4.055" of liquid (or liquid equivalent) precipitation, compared to a median value of 0.124". The month with the most precipitation was June, with 10.858", compared to a median value of 2.606".

As determined by quantitative measurements, the longest dry spell was from January 28 to February 20, constituting 24 consecutive days with no measured precipitation. The month with the largest fraction of dry days was January, with 90% of days reporting no measured precipitation at all.

The month with the largest fraction of days with at least some measured precipitation was May, with 45% of days reporting some measured precipitation.

Precipitation Quantity

The daily measured quantity of liquid (or liquid equivalent in the case of solid precipitation) precipitation over the course of 2012, with the median non-zero quantity (thick gray line) and 10th, 25th, 75th, and 90th non-zero percentiles (shaded areas). The bar at the top of the graph is green if any precipitation was measured that day and white otherwise.

Either snow is exceptionally rare at this location or this station did not reliably report it during 2012.

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 2012 was September with an average daily low humidity of 33%, and the most humid month was December with an average daily low humidity of 62%.

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 2012 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 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 2012, January had 31 dry days, no comfortable days, and no humid days; April had 30 dry days, no comfortable days, and no humid days; July had no dry days, 11 comfortable days, and 20 humid days; and October had 30 dry days, 1 comfortable day, and no humid days.

Dew Point

The daily low (blue) and high (red) dew point during 2012 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 highest sustained wind speed was 25 mph, occurring on March 19; the highest daily mean wind speed was 17 mph (March 27); and the highest wind gust speed was 39 mph (January 1).

The windiest month was April, with an average wind speed of 7 mph. The least windy month was August, with an average wind speed of 4 mph.

Wind Speed

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

Visibility is the maximum distance at which a given reference object or light can be clearly discerned. In the United States, visibilities that are greater than or equal to 10 miles are typically reported as 10 miles.

The day of 2012 with the lowest average visibility was December 1, with an average visibility of 1.7 mi. The month with the lowest average visibility was December, with an average visibility of 8.1 mi. With an average visibility of 9.6 mi, the month of April had the highest average visibility.

Visibility

The daily average visibility, depicted as gray bars encroaching down from the top of the graph.

The cloud ceiling is the altitude of the lowest layer of clouds that are at categorized as broken (mostly cloudy) or overcast (cloudy). If no such cloud layer exists then the ceiling is unlimited and no value is reported.

The day of 2012 with the lowest average cloud ceiling was June 25, with an average cloud ceiling of 98'. The month with the lowest average cloud ceiling was February, with an average cloud ceiling of 3091'. The month of September has the highest average cloud ceiling, with an average cloud ceiling of 5161'.

Cloud Ceiling

The daily average cloud ceiling, depicted as gray bars encroaching down from the top of the graph. Missing data or days with insufficient clouds to define a cloud ceiling are shown as white columns.