Average Weather at Spencer Municipal Airport Iowa, United States

At Spencer Municipal Airport, the summers are long, warm, and wet; the winters are freezing, snowy, and windy; and it is partly cloudy year round. Over the course of the year, the temperature typically varies from 9°F to 84°F and is rarely below -12°F or above 92°F.

The warm season lasts for 4.0 months, from May 20 to September 21, with an average daily high temperature above 72°F. The hottest day of the year is July 18, with an average high of 84°F and low of 63°F.

The cold season lasts for 3.3 months, from November 26 to March 4, with an average daily high temperature below 38°F. The coldest day of the year is January 20, with an average low of 9°F and high of 26°F.

The figure below shows you a compact characterization of the entire year of hourly average temperatures. The horizontal axis is the day of the year, the vertical axis is the hour of the day, and the color is the average temperature for that hour and day.

Average Hourly Temperature

The average hourly temperature, color coded into bands: frigid < 15°F < freezing < 32°F < chilly < 45°F < cold < 55°F < cool < 65°F < comfortable < 75°F < warm < 85°F < hot < 95°F < sweltering. The shaded overlays indicate night and civil twilight.

Clouds

At Spencer Municipal Airport, the average percentage of the sky covered by clouds experiences significant seasonal variation over the course of the year.

The clearer part of the year at Spencer Municipal Airport begins around June 8 and lasts for 4.4 months, ending around October 19. On July 28, the clearest day of the year, the sky is clear, mostly clear, or partly cloudy 73% of the time, and overcast or mostly cloudy 27% of the time.

The cloudier part of the year begins around October 19 and lasts for 7.6 months, ending around June 8. On February 3, the cloudiest day of the year, the sky is overcast or mostly cloudy 56% of the time, and clear, mostly clear, or partly cloudy 44% of the time.

Cloud Cover

The percentage of time spent in each cloud cover band, categorized by the percentage of the sky covered by clouds: clear < 20% < mostly clear < 40% < partly cloudy < 60% < mostly cloudy < 80% < overcast.

Precipitation

A wet day is one with at least 0.04 inches of liquid or liquid-equivalent precipitation. The chance of wet days at Spencer Municipal Airport varies significantly throughout the year.

The wetter season lasts 6.0 months, from April 6 to October 6, with a greater than 24% chance of a given day being a wet day. The chance of a wet day peaks at 41% on June 7.

The drier season lasts 6.0 months, from October 6 to April 6. The smallest chance of a wet day is 7% on January 14.

Among wet days, we distinguish between those that experience rain alone, snow alone, or a mixture of the two. Based on this categorization, the most common form of precipitation at Spencer Municipal Airport changes throughout the year.

Rain alone is the most common for 8.9 months, from March 1 to November 27. The highest chance of a day with rain alone is 41% on June 7.

Snow alone is the most common for 3.1 months, from November 27 to March 1. The highest chance of a day with snow alone is 6% on January 18.

Daily Chance of Precipitation

The percentage of days in which various types of precipitation are observed, excluding trace quantities: rain alone, snow alone, and mixed (both rain and snow fell in the same day).

Rainfall

To show variation within the months and not just the monthly totals, we show the rainfall accumulated over a sliding 31-day period centered around each day of the year. Spencer Municipal Airport experiences extreme seasonal variation in monthly rainfall.

The rainy period of the year lasts for 9.0 months, from March 2 to December 1, with a sliding 31-day rainfall of at least 0.5 inches. The most rain falls during the 31 days centered around June 16, with an average total accumulation of 4.3 inches.

The rainless period of the year lasts for 3.0 months, from December 1 to March 2. The least rain falls around January 23, with an average total accumulation of 0.1 inches.

Average Monthly Rainfall

The average rainfall (solid line) accumulated over the course of a sliding 31-day period centered on the day in question, with 25th to 75th and 10th to 90th percentile bands. The thin dotted line is the corresponding average liquid-equivalent snowfall.

Snowfall

We report snowfall in liquid-equivalent terms. The actual depth of new snowfall is typically between 5 and 10 times the liquid-equivalent amount, assuming the ground is frozen. Colder, drier snow tends to be on the higher end of that range and warmer, wetter snow on the lower end.

As with rainfall, we consider the snowfall accumulated over a sliding 31-day period centered around each day of the year. Spencer Municipal Airport experiences some seasonal variation in monthly liquid-equivalent snowfall.

The snowy period of the year lasts for 5.5 months, from October 27 to April 12, with a sliding 31-day liquid-equivalent snowfall of at least 0.1 inches. The most snow falls during the 31 days centered around December 8, with an average total liquid-equivalent accumulation of 0.4 inches.

The snowless period of the year lasts for 6.5 months, from April 12 to October 27. The least snow falls around July 17, with an average total liquid-equivalent accumulation of 0.0 inches.

Average Liquid-Equivalent Monthly Snowfall

The average liquid-equivalent snowfall (solid line) accumulated over the course of a sliding 31-day period centered on the day in question, with 25th to 75th and 10th to 90th percentile bands. The thin dotted line is the corresponding average rainfall.

Sun

The length of the day at Spencer Municipal Airport varies significantly over the course of the year. In 2017, the shortest day is December 21, with 8 hours, 59 minutes of daylight; the longest day is June 21, with 15 hours, 23 minutes of daylight.

Hours of Daylight and Twilight

The number of hours during which the Sun is visible (black line). From bottom (most yellow) to top (most gray), the color bands indicate: full daylight, twilight (civil, nautical, and astronomical), and full night.

The earliest sunrise is at 5:40 AM on June 15, and the latest sunrise is 2 hours, 19 minutes later at 7:59 AM on November 4. The earliest sunset is at 4:45 PM on December 7, and the latest sunset is 4 hours, 19 minutes later at 9:04 PM on June 26.

Daylight saving time (DST) is observed at Spencer Municipal Airport during 2017, starting in the spring on March 12, lasting 7.8 months, and ending in the fall on November 5.

Sunrise & Sunset with Twilight and Daylight Saving Time

The solar day over the course of the year 2017. From bottom to top, the black lines are the previous solar midnight, sunrise, solar noon, sunset, and the next solar midnight. The day, twilights (civil, nautical, and astronomical), and night are indicated by the color bands from yellow to gray. The transitions to and from daylight saving time are indicated by the 'DST' labels.

Humidity

We base the humidity comfort level on the dew point, as it determines whether perspiration will evaporate from the skin, thereby cooling the body. Lower dew points feel drier and higher dew points feel more humid. Unlike temperature, which typically varies significantly between night and day, dew point tends to change more slowly, so while the temperature may drop at night, a muggy day is typically followed by a muggy night.

Spencer Municipal Airport experiences significant seasonal variation in the perceived humidity.

The muggier period of the year lasts for 3.2 months, from June 8 to September 14, during which time the comfort level is muggy, oppressive, or miserable at least 11% of the time. The muggiest day of the year is July 21, with muggy conditions 42% of the time.

The least muggy day of the year is February 16, when muggy conditions are essentially unheard of.

Humidity Comfort Levels

The percentage of time spent at various humidity comfort levels, categorized by dew point: dry < 55°F < comfortable < 60°F < humid < 65°F < muggy < 70°F < oppressive < 75°F < miserable.

Wind

This section discusses the wide-area hourly average wind vector (speed and direction) at 10 meters above the ground. The wind experienced at any given location is highly dependent on local topography and other factors, and instantaneous wind speed and direction vary more widely than hourly averages.

The average hourly wind speed at Spencer Municipal Airport experiences mild seasonal variation over the course of the year.

The windier part of the year lasts for 8.2 months, from September 25 to June 1, with average wind speeds of more than 6.0 miles per hour. The windiest day of the year is April 8, with an average hourly wind speed of 7.3 miles per hour.

The calmer time of year lasts for 3.8 months, from June 1 to September 25. The calmest day of the year is August 3, with an average hourly wind speed of 4.7 miles per hour.

Average Wind Speed

The average of mean hourly wind speeds (dark gray line), with 25th to 75th and 10th to 90th percentile bands.

The predominant average hourly wind direction at Spencer Municipal Airport varies throughout the year.

The wind is most often from the south for 6.6 months, from May 4 to November 23, with a peak percentage of 47% on September 3. The wind is most often from the north for 2.4 weeks, from November 23 to December 10 and for 4.5 months, from December 20 to May 4, with a peak percentage of 31% on December 5. The wind is most often from the west for 1.4 weeks, from December 10 to December 20, with a peak percentage of 32% on December 16.

Wind Direction

The percentage of hours in which the mean wind direction is from each of the four cardinal wind directions (north, east, south, and west), excluding hours in which the mean wind speed is less than 1 mph. The lightly tinted areas at the boundaries are the percentage of hours spent in the implied intermediate directions (northeast, southeast, southwest, and northwest).

Solar Energy

This section discusses the total daily incident shortwave solar energy reaching the surface of the ground over a wide area, taking full account of seasonal variations in the length of the day, the elevation of the Sun above the horizon, and absorption by clouds and other atmospheric constituents. Shortwave radiation includes visible light and ultraviolet radiation.

The average daily incident shortwave solar energy experiences extreme seasonal variation over the course of the year.

The brighter period of the year lasts for 3.5 months, from May 4 to August 21, with an average daily incident shortwave energy per square meter above 6.0 kWh. The brightest day of the year is July 8, with an average of 7.1 kWh.

The darker period of the year lasts for 3.4 months, from October 30 to February 11, with an average daily incident shortwave energy per square meter below 2.8 kWh. The darkest day of the year is December 19, with an average of 1.7 kWh.

Average Daily Incident Shortwave Solar Energy

The average daily shortwave solar energy reaching the ground per square meter (orange line), with 25th to 75th and 10th to 90th percentile bands.

Topography

For the purposes of this report, the geographical coordinates of Spencer Municipal Airport are 43.164 deg latitude, -95.202 deg longitude, and 1,332 ft elevation.

The topography within 2 miles of Spencer Municipal Airport is essentially flat, with a maximum elevation change of 39 feet and an average elevation above sea level of 1,330 feet. Within 10 miles is essentially flat (207 feet). Within 50 miles contains only modest variations in elevation (705 feet).

The area within 2 miles of Spencer Municipal Airport is covered by cropland (98%), within 10 miles by cropland (98%), and within 50 miles by cropland (98%).

Data Sources

This report illustrates the typical weather at Spencer Municipal Airport, based on a statistical analysis of historical hourly weather reports and model reconstructions from January 1, 1980 to December 31, 2016.

Temperature and Dew Point

Spencer Municipal Airport has a weather station that reported reliably enough during the analysis period that we have included it in our network. When available, historical temperature and dew point measurements are taken directly from this weather station. These records are obtained from NOAA's Integrated Surface Hourly data set, falling back on ICAO METAR records as required.

In the case of missing or erroneous measurements from this station, we fall back on records from nearby stations, adjusted according to typical seasonal and diurnal intra-station differences. For a given day of the year and hour of the day, the fallback station is selected to minimize the prediction error over the years for which there are measurements for both stations.

The stations on which we may fall back include but are not limited to Estherville Municipal Airport, Jackson Municipal Airport, Cherokee Municipal Airport, Storm Lake Municipal Airport, Worthington Municipal Airport, Sheldon, Windom Municipal Airport, and Orange City Municipal Airport.

Other Data

All data relating to the Sun's position (e.g., sunrise and sunset) are computed using astronomical formulas from the book, Astronomical Tables of the Sun, Moon and Planets , by Jean Meeus.

All other weather data, including cloud cover, precipitation, wind speed and direction, and solar flux, come from NASA's MERRA-2 Modern-Era Retrospective Analysis . This reanalysis combines a variety of wide-area measurements in a state-of-the-art global meteorological model to reconstruct the hourly history of weather throughout the world on a 50-kilometer grid.

Land Use data comes from the Global Land Cover SHARE database , published by the Food and Agriculture Organization of the United Nations.

Elevation data comes from the Shuttle Radar Topography Mission (SRTM) , published by NASA's Jet Propulsion Laboratory.

Names, locations, and time zones of places and some airports come from the GeoNames Geographical Database .

Time zones for aiports and weather stations are provided by AskGeo.com .

Maps are © Esri, with data from National Geographic, Esri, DeLorme, NAVTEQ, UNEP-WCMC, USGS, NASA, ESA, METI, NRCAN, GEBCO, NOAA, and iPC.