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Average Weather in Irondale Alabama, United States

In Irondale, the summers are long, hot, and muggy; the winters are short, cold, and wet; and it is partly cloudy year round. Over the course of the year, the temperature typically varies from 35°F to 89°F and is rarely below 21°F or above 96°F.

Climate Summary

coldcoolwarmhotwarmcoolJanFebMarAprMayJunJulAugSepOctNovDec67%67%46%46%clearovercastprecipitation: 5.1 inprecipitation: 5.1 in2.9 in2.9 inmuggy: 89%muggy: 89%0%0%drydrytourism score: 6.4tourism score: 6.41.31.3
Click on each chart for more information.

Based on the tourism score, the best times of year to visit Irondale for warm-weather activities are from late April to mid June and from late August to mid October.

Temperature

The hot season lasts for 3.9 months, from May 25 to September 22, with an average daily high temperature above 82°F. The hottest day of the year is July 22, with an average high of 89°F and low of 72°F.

The cool season lasts for 2.9 months, from November 29 to February 24, with an average daily high temperature below 60°F. The coldest day of the year is January 23, with an average low of 35°F and high of 54°F.

Average High and Low Temperature

The daily average high (red line) and low (blue line) temperature, with 25th to 75th and 10th to 90th percentile bands. The thin dotted lines are the corresponding average perceived temperatures.

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

Average Hourly Temperature in IrondaleJanFebMarAprMayJunJulAugSepOctNovDec12 AM4 AM8 AM12 PM4 PM8 PM12 AMvery coldvery coldcoldcoldcoolcoolcomfortablewarmhotvery coldwarmvery cold
The average hourly temperature, color coded into bands: frigid < 15°F < freezing < 32°F < very cold < 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.

Baiyun, China (7,999 miles away) is the far-away foreign place with temperatures most similar to Irondale (view comparison).

Clouds

In Irondale, 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 in Irondale begins around July 14 and lasts for 4.3 months, ending around November 24. On October 12, the clearest day of the year, the sky is clear, mostly clear, or partly cloudy 67% of the time, and overcast or mostly cloudy 33% of the time.

The cloudier part of the year begins around November 24 and lasts for 7.7 months, ending around July 14. On January 5, the cloudiest day of the year, the sky is overcast or mostly cloudy 54% of the time, and clear, mostly clear, or partly cloudy 46% of the time.

Cloud Cover Categories

Cloud Cover Categories in IrondaleclearercloudiercloudierJanFebMarAprMayJunJulAugSepOctNovDec0%100%10%90%20%80%30%70%40%60%50%50%60%40%70%30%80%20%90%10%100%0%Oct 1267%Oct 1267%Jan 546%Jan 546%Jul 1456%Jul 1456%Nov 2457%Nov 2457%clearmostly clearpartly cloudyovercast
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 in Irondale varies throughout the year.

The wetter season lasts 7.2 months, from January 20 to August 25, with a greater than 32% chance of a given day being a wet day. The chance of a wet day peaks at 44% on July 9.

The drier season lasts 4.8 months, from August 25 to January 20. The smallest chance of a wet day is 20% on October 8.

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 throughout the year is rain alone, with a peak probability of 44% on July 9.

Daily Chance of Precipitation

Daily Chance of Precipitation in IrondalewetdrydryJanFebMarAprMayJunJulAugSepOctNovDec0%10%20%30%40%50%60%70%80%90%100%Jul 944%Jul 944%Oct 820%Oct 820%Jan 130%Jan 130%Jan 2032%Jan 2032%Aug 2532%Aug 2532%rain
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. Irondale experiences significant seasonal variation in monthly rainfall.

Rain falls throughout the year in Irondale. The most rain falls during the 31 days centered around February 28, with an average total accumulation of 5.1 inches.

The least rain falls around August 23, with an average total accumulation of 2.9 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

The sliding 31-day liquid-equivalent quantity of snowfall in Irondale does not vary significantly over the course of the year, staying within 0.1 inches of 0.1 inches throughout.

Average Liquid-Equivalent Monthly Snowfall

Average Liquid-Equivalent Monthly Snowfall in IrondaleJanFebMarAprMayJunJulAugSepOctNovDec0 in1 in2 in3 in4 in5 inJan 200.1 inJan 200.1 inJul 290.0 inJul 290.0 in
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 in Irondale varies significantly over the course of the year. In 2017, the shortest day is December 21, with 9 hours, 56 minutes of daylight; the longest day is June 20, with 14 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 5:36 AM on June 12, and the latest sunrise is 1 hour, 32 minutes later at 7:08 AM on November 4. The earliest sunset is at 4:38 PM on December 4, and the latest sunset is 3 hours, 22 minutes later at 8:00 PM on June 29.

Daylight saving time (DST) is observed in Irondale 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

Sunrise & Sunset with Twilight and Daylight Saving Time in IrondaleJanFebMarAprMayJunJulAugSepOctNovDec12 AM2 AM4 AM6 AM8 AM10 AM12 PM2 PM4 PM6 PM8 PM10 PM12 AMJun 125:36 AMJun 125:36 AM8:00 PMJun 298:00 PMJun 29Dec 44:38 PMDec 44:38 PM7:08 AMNov 47:08 AMNov 4Mar 12DSTMar 12DSTDSTNov 5DSTNov 5daynightnightnightnightSolarMidnightSolarMidnightSolarNoonSunriseSunset
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.

Irondale experiences extreme seasonal variation in the perceived humidity.

The muggier period of the year lasts for 4.6 months, from May 14 to October 2, during which time the comfort level is muggy, oppressive, or miserable at least 22% of the time. The muggiest day of the year is July 25, with muggy conditions 89% of the time.

The least muggy day of the year is January 24, when muggy conditions are essentially unheard of.

Humidity Comfort Levels

Humidity Comfort Levels in IrondalemuggyJanFebMarAprMayJunJulAugSepOctNovDec0%10%20%30%40%50%60%70%80%90%100%Jan 240%Jan 240%89%Jul 2589%Jul 25May 1422%May 1422%Oct 222%Oct 222%oppressiveoppressivemuggymuggydrydryhumidhumidcomfortablecomfortablemiserablemiserable
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 in Irondale experiences mild seasonal variation over the course of the year.

The windier part of the year lasts for 7.2 months, from October 8 to May 14, with average wind speeds of more than 4.1 miles per hour. The windiest day of the year is February 26, with an average hourly wind speed of 5.2 miles per hour.

The calmer time of year lasts for 4.8 months, from May 14 to October 8. The calmest day of the year is August 4, with an average hourly wind speed of 3.1 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 in Irondale varies throughout the year.

The wind is most often from the south for 4.3 months, from February 26 to July 3; for 2.4 weeks, from July 29 to August 15; and for 1.2 months, from November 12 to December 17, with a peak percentage of 44% on May 4. The wind is most often from the east for 1.6 months, from August 15 to October 4, with a peak percentage of 36% on September 15. The wind is most often from the north for 1.3 months, from October 4 to November 12 and for 2.3 months, from December 17 to February 26, with a peak percentage of 33% on October 12.

Wind Direction

Wind Direction in IrondaleNSWSENSNJanFebMarAprMayJunJulAugSepOctNovDec0%100%20%80%40%60%60%40%80%20%100%0%westsoutheastnorth
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).

Best Time of Year to Visit

To characterize how pleasant the weather is in Irondale throughout the year, we compute two travel scores.

The tourism score favors clear, rainless days with perceived temperatures between 65°F and 80°F. Based on this score, the best times of year to visit Irondale for general outdoor tourist activities are from late April to mid June and from late August to mid October, with a peak score in the third week of September.

Tourism Score

Tourism Score in Irondalebest timebest timeJanFebMarAprMayJunJulAugSepOctNovDec02468106.46.41.31.36.26.25.15.1 precipitationprecipitationcloudscloudstemperaturetemperaturetourism score
The tourism score (filled area), and its constituents: the temperature score (red line), the cloud cover score (blue line), and the precipitation score (green line).

The beach/pool score favors clear, rainless days with perceived temperatures between 75°F and 90°F. Based on this score, the best time of year to visit Irondale for hot-weather activities is from early June to mid September, with a peak score in the third week of August.

Beach/Pool Score

Beach/Pool Score in Irondalebest timeJanFebMarAprMayJunJulAugSepOctNovDec02468106.46.40.10.1 precipitationprecipitationcloudscloudstemperaturetemperaturebeach/pool score
The beach/pool score (filled area), and its constituents: the temperature score (red line), the cloud cover score (blue line), and the precipitation score (green line).

Methodology

For each hour between 8:00 AM and 9:00 PM of each day in the analysis period (1980 to 2016), independent scores are computed for perceived temperature, cloud cover, and total precipitation. Those scores are combined into a single hourly composite score, which is then aggregated into days, averaged over all the years in the analysis period, and smoothed.

Our cloud cover score is 10 for fully clear skies, falling linearly to 9 for mostly clear skies, and to 1 for fully overcast skies.

Our precipitation score, which is based on the three-hour precipitation centered on the hour in question, is 10 for no precipitation, falling linearly to 9 for trace precipitation, and to 0 for 0.04 inches of precipitation or more.

Our tourism temperature score is 0 for perceived temperatures below 50°F, rising linearly to 9 for 65°F, to 10 for 75°F, falling linearly to 9 for 80°F, and to 1 for 90°F or hotter.

Our beach/pool temperature score is 0 for perceived temperatures below 65°F, rising linearly to 9 for 75°F, to 10 for 82°F, falling linearly to 9 for 90°F, and to 1 for 100°F or hotter.

Growing Season

Definitions of the growing season vary throughout the world, but for the purposes of this report, we define it as the longest continuous period of non-freezing temperatures (≥ 32°F) in the year (the calendar year in the Northern Hemisphere, or from July 1 until June 30 in the Southern Hemisphere).

The growing season in Irondale typically lasts for 7.5 months (231 days), from around March 25 to around November 11, rarely starting before February 27 or after April 17, and rarely ending before October 24 or after November 29.

Time Spent in Various Temperature Bands and the Growing Season

Time Spent in Various Temperature Bands and the Growing Season in Irondalegrowing seasonJanFebMarAprMayJunJulAugSepOctNovDec0%100%10%90%20%80%30%70%40%60%50%50%60%40%70%30%80%20%90%10%100%0%50%Mar 2550%Mar 2550%Nov 1150%Nov 1190%Apr 1790%Apr 1790%Oct 2490%Oct 2410%Feb 2710%Feb 2710%Nov 2910%Nov 290%Dec 250%Dec 25Jul 23100%Jul 23100%freezingvery coldcoldcoolcomfortablewarmhot
The percentage of time spent in various temperature bands: frigid < 15°F < freezing < 32°F < very cold < 45°F < cold < 55°F < cool < 65°F < comfortable < 75°F < warm < 85°F < hot < 95°F < sweltering. The black line is the percentage chance that a given day is within the growing season.

Growing degree days are a measure of yearly heat accumulation used to predict plant and animal development, and defined as the integral of warmth above a base temperature, discarding any excess above a maximum temperature. In this report, we use a base of 50°F and a cap of 86°F.

Based on growing degree days alone, the first spring blooms in Irondale should appear around February 6, only rarely appearing before January 20 or after February 26.

Growing Degree Days

The average growing degree days accumulated over the course of the year, with 25th to 75th and 10th to 90th percentile bands.

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 significant seasonal variation over the course of the year.

The brighter period of the year lasts for 4.7 months, from April 9 to August 30, with an average daily incident shortwave energy per square meter above 5.8 kWh. The brightest day of the year is June 5, with an average of 6.6 kWh.

The darker period of the year lasts for 2.7 months, from November 14 to February 4, with an average daily incident shortwave energy per square meter below 3.4 kWh. The darkest day of the year is December 24, with an average of 2.5 kWh.

Average Daily Incident Shortwave Solar Energy

Average Daily Incident Shortwave Solar Energy in IrondalebrightdarkdarkJanFebMarAprMayJunJulAugSepOctNovDec0 kWh1 kWh2 kWh3 kWh4 kWh5 kWh6 kWh7 kWh8 kWh9 kWhJun 56.6 kWhJun 56.6 kWhDec 242.5 kWhDec 242.5 kWhApr 95.8 kWhApr 95.8 kWhAug 305.8 kWhAug 305.8 kWhFeb 43.4 kWhFeb 43.4 kWh
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 Irondale are 33.538 deg latitude, -86.707 deg longitude, and 758 ft elevation.

The topography within 2 miles of Irondale contains significant variations in elevation, with a maximum elevation change of 577 feet and an average elevation above sea level of 808 feet. Within 10 miles contains significant variations in elevation (1,089 feet). Within 50 miles also contains very significant variations in elevation (1,781 feet).

The area within 2 miles of Irondale is covered by artificial surfaces (76%) and trees (24%), within 10 miles by artificial surfaces (57%) and trees (39%), and within 50 miles by trees (69%) and cropland (17%).

Data Sources

This report illustrates the typical weather in Irondale, 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

There are 4 weather stations near enough to contribute to our estimation of the temperature and dew point in Irondale.

For each station, the records are corrected for the elevation difference between that station and Irondale according to the International Standard Atmosphere , and by the relative change present in the MERRA-2 satellite-era reanalysis between the two locations.

The estimated value at Irondale is computed as the weighted average of the individual contributions from each station, with weights proportional to the inverse of the distance between Irondale and a given station.

The stations contributing to this reconstruction are: Birmingham–Shuttlesworth International Airport (90%, 4.7 kilometers, northwest); Shelby County Airport (6%, 41 kilometers, south); Northeast Alabama Regional Airport (2.3%, 75 kilometers, northeast); and Anniston Metropolitan Airport (2.1%, 79 kilometers, east).

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.

Disclaimer

The information on this site is provided as is, without any assurances as to its accuracy or suitability for any purpose. Weather data is prone to errors, outages, and other defects. We assume no responsibility for any decisions made on the basis of the content presented on this site.

We draw particular cautious attention to our reliance on the MERRA-2 model-based reconstructions for a number of important data series. While having the tremendous advantages of temporal and spatial completeness, these reconstructions: (1) are based on computer models that may have model-based errors, (2) are coarsely sampled on a 50 km grid and are therefore unable to reconstruct the local variations of many microclimates, and (3) have particular difficulty with the weather in some coastal areas, especially small islands.

We further caution that our travel scores are only as good as the data that underpin them, that weather conditions at any given location and time are unpredictable and variable, and that the definition of the scores reflects a particular set of preferences that may not agree with those of any particular reader.