2012 Spring Climate Summary - Warmest on Record at Indianapolis

Spring 2012 in Review
With June 1 comes the end of meteorological spring, a period defined as covering the months of March through May. The spring of 2012 in central Indiana will go down as the warmest on record. At Indianapolis, the old record average temperature of 58.1 degrees set during the spring of 1977 was shattered by almost two degrees. This included the warmest March on record, when most locations across central Indiana experienced average temperatures of 13 to 16 degrees above normal. Drier than normal conditions were also experienced across central Indiana throughout the spring, with many locations ending up three to six inches below normal on precipitation throughout the period. By the end of May, the U.S. Drought Monitor had expanded drought conditions to encompass around 50% of the state.
The following is a review of weather conditions experienced in central Indiana during the 2012 spring season.


March 2012 will go down in history as the warmest March of record in Indianapolis, and nearly a whopping 15 degrees above normal. The last time the record average temperature for a month was tied occurred when March 1946 equaled the record warm March 1910. The last time a record monthly average temperature was set happened at the close of August 1936 during the Heat Wave of 1936. Even more impressive, the average temperature for March 2012 shattered the previous record from March 1910 by nearly 5 degrees.

The record warmth of March resulted from an upper level ridge that remained over the Indianapolis area from March 14-22. June like weather prevailed for more than a week. Daily temperatures averaged more than 20 degrees above normal during this period. The 11-day period from March 12-22 was the warmest of any 11-day period so early in the year prior to April 20. At Indianapolis, the temperature made it to 70 degrees or warmer on 14 days, and 80 degrees or warmer on 7 days this month, both of which had never happened on so many days in any previous March on record. Indianapolis made it to 84 degrees on the afternoon of the 21st, the warmest temperature during the month and just missing the all-time record high of 85 degrees set on March 31, 1981.


Because of the warm winter and the sudden onset of extended early summer weather, vegetation sprang to life overnight. Early spring flowers bloomed very quickly and faded in a couple of days. Tulips, lilacs, flowering bushes and trees were in full bloom during the last week of March. Many trees were budding including oaks. Lawn mowers were heard everywhere as grasses literally grew more than 6 inches overnight. The outdoors was typical of early May rather than late March.

The warm temperatures of March were not confined to the Indianapolis area. Much of the Midwest and east coast shared in the summer like weather. To quote what Weather Bureau officials stated in March 1910, "Never since the Weather Bureau was established has there been such an early opening of spring." The U.S. Weather Bureau became the National Weather Service in 1970. Weather records at Indianapolis began in 1871.


It may seem hard to believe after such a warm month, but March did have a chilly stretch early in the month after a strong cold front passes through the region on the 2nd. High temperatures were at or below 40 degrees March 3rd through 5th over much of central Indiana before a rapid warmup began with highs in the mid and upper 60s from the 6th through the 8th. Many locations across central Indiana experienced a high in the 40s on the 9th in the wake of another frontal passage. However, much of central Indiana experienced high temperatures at 50 degrees or warmer for the remainder of the month as the record warmth began in earnest.



The last few days of the persistent March warmth lingered into the first few days of April, with highs topping out in the lower and middle 80s on the 3rd. Cooler weather followed through much of the rest of the first half of the month as a broad upper level trough established across the Great Lakes and brought repeated surges of colder air into the region. Many locations across central Indiana in fact did not see high temperatures warm above 70 degrees again until the 15th. Low temperatures cooling into the upper 20s and lower 30s on several mornings through this period brought concerns about frost accrual and the impacts of subfreezing temperatures to vegetation that had been substantially advanced in growth courtesy of the record warmth in March. Most locations experienced their coolest temperatures on the mornings of the 11th and 12th as temperatures fell into the 25 to 30 degree range. Despite the cold mornings, impacts to vegetation across central Indiana appeared to be minor.

Warmer temperatures returned from the 15th through the 20th before a cold frontal passage ushered in another period of much cooler temperatures as large high pressure expanded south from Canada. High temperatures in the 50s were common across central Indiana from the 21st through the 23rd with lows once again falling back into the 30s before a brief warmup in the few days that followed. The arrival of a nearly stationary warm front into southern Indiana for the last few days of the month brought large temperature differences to the region. Temperatures north of the front struggled to climb out of the 50s while highs warmed into the 70s along and south of the boundary. As the boundary pushed north on the 30th, much of central Indiana warmed into the 70s and lower 80s, making the last day of the month the warmest day since the 3rd for much of the region.


Indianapolis marked another rare occurrence for Spring 2012 during April. The average temperature for April was 2.1 degrees cooler than March. Typically the average monthly temperature increases nearly 11 degrees from March to April. This was only the second time since 1872 when March was warmer than April. The only other occurrence was in 1907. It is interesting to note that both events were caused by either a record warm or record cold month. In 1907, March was followed by the coldest April of record. This year a record warm March is followed by an April with an average monthly temperature that was only 1.5 degrees above normal. In fact, the other six major climate reporting stations within central Indiana also experienced average temperatures in April that were generally a degree or two cooler than those experienced in March.

Temperatures started the month out warm as a frontal boundary oscillated across the Ohio Valley through May 7. Much of central Indiana was along and south of the boundary with high temperatures commonly in the upper 70s to middle 80s. The frontal boundary finally moved away from the region on the 8th, ushering in the coolest days of May. High temperatures were in the upper 60s and lower 70s and lows falling back into the 40s. A few locations even bottomed out in the upper 30s on the mornings of the 9th and 10th.

High pressure remained the dominant influence over central Indiana and much of the Ohio Valley through the middle of the month, bringing dry weather with plenty of sunny days and mainly clear and cool nights. Temperatures were near average with highs in the 70s to around 80 and lows ranging from the middle 40s to middle 50s from the 11th through the 17th. Beginning on the 18th, an upper ridge expanded into the Ohio Valley with high temperatures warming into the upper 80s and lower 90s on the 19th and 20th. The passage of a weakening cold front on the 21st brought temperatures back down into the upper 60s and lower 70s for much of central Indiana. The cool down was temporary. A steady warming trend commenced on the 23rd and persisted right through the Memorial Day weekend. Indiana experienced the warmest weather of the year to date as highs on the 26th, 27th and 28th topped out in the lower and middle 90s. This was the longest and hottest heat wave since early September 2011. A passing cold front brought relief to the state on the 29th. May ended on the mild side.


Temperature Data for Sites in Central Indiana
Spring 2012 Temperature
Normal Temperature
Diff. From Normal
Indianapolis Int’l Airport
Terre Haute
Indianapolis – Eagle Creek
Spring Extremes Across Central Indiana
Warmest Temperature
Coldest Temperature
Indianapolis Int’l Airport
92 on 5/28
25 on 3/4
93 on 5/27 and 5/28
24 on 3/5 and 3/10
94 on 5/27
21 on 3/10
Terre Haute
96 on 5/27 and 5/28
24 on 3/5
92 on 5/27 and 5/28
23 on 3/5
93 on 5/27 and 5/28
25 on 3/10
Indianapolis-Eagle Creek
91 on 5/27 and 5/28
25 on 3/10
Precipitation during March ranged from less than an inch in west central Indiana to more than 6 inches in extreme south central Indiana. Much of the western half of Indiana was on the dry side while normal to wetter than normal conditions prevailed in the eastern half. Rainfall in most areas of central and southern Indiana varied from 1.5 to 3.5 inches. Precipitation during the month fell primarily in the form of rain.
Lowland flooding and near bankfull conditions occurred along in the White River basin following locally heavy rains of 2 to nearly 4 inches on the 22nd and 23rd. Lowland flooding along portions of the East Fork White and Muscatatuck rivers lasted about 3 days. Localized flooding occurred in portions of Shelby, Johnson and Jennings Counties.  
A cold front brought scattered thunderstorms during the afternoon and evening of the 30th. Most locations across central Indiana received a half to three quarters of an inch of rain. Heavier rainfall up to two inches occurred from Brown and Lawrence Counties east through Decatur and Jennings Counties, causing some localized flooding.
Snowfall totals in March ranged from a trace to nearly 7 inches. All of the snow fell before the 6th. The heaviest snow fell in southern Indiana late on the 4th and early on the 5th. The areas devastated by the tornadoes on the 2nd received 2 to 4 inches of snow. The heaviest snow fell in Martin County. This was the biggest snowfall of the winter season for southern Indiana.
April was a dry month in much of Indiana especially in southwest and northern Indiana. Monthly rainfall totaled from one-half of an inch in portions of north central Indiana to nearly 6 inches at some locations in southern Indiana. Most areas received between 1 and 3 inches of rainfall during April.
Drought conditions appeared for the first in the state since last October. The U.S. Drought Monitor indicated abnormally dry conditions in portions of western Indiana as of April 24th. Little or no rain fell in much of Indiana north of Interstate 70 from the 1st through the 13th.   Rainfall was absent from nearly the entire state from the 5th through the 13th. Windy and dry conditions raised wildfire concerns during this time. Indiana farmers took advantage of the dry weather and planted corn and soybeans at a record pace according to the Indiana Field Office of USDA’s National Agricultural Statistics Service. Some farmers stopped planting when soils became too dry for crop germination.
Widespread showers and thunderstorms on the afternoon and evening of the 30th alleviated dry conditions to some extent. Most areas in the state received one quarter to one inch of rainfall. April was the first month without river flooding since October.
May was another dry month in much of Indiana especially in portions of southwest and northeast Indiana. Monthly rainfall totaled from around one-half of an inch in southwest and northeast Indiana to more than 9 inches in Harrison County in extreme south central Indiana. Most areas received between 1 and 4 inches of rainfall during May.
Rainfall was not evenly distributed during May. Most locations went from 20 to 26 days with very little rainfall. Rainfall of 1 to 3 inches in central Indiana on May 1st caused localized high water and bankfull conditions along the Eel, White and East Fork White Rivers during the first week of May. Rainfall of 3 to 6 inches in portions of Jackson, Washington and eastern Lawrence counties on the evening of May 4th caused brief flooding along the Muscatatuck River in southwest Jackson County. Rainfall was nearly absent from the state from the 10th through 28th.  Rainfall on May 29th in central and southern Indiana and cooler weather alleviated dry conditions to some extent. Significant rainfall during the waning hours of May and continuing into early June provided some additional relief.
Drought conditions expanded during the month of May. The U.S. Drought Monitor on May 29th indicated 50% of the state in drought conditions. Dry conditions in Vigo and Sullivan counties prompted county wide burning bans during the latter part of May. Replanting of crops was necessary in some areas because of drought stress.
Spring Precipitation Data for Sites in Central Indiana
Spring 2012 Precipitation
Normal Precipitation
Diff. From Normal
Indianapolis Int’l Airport
Terre Haute
Indianapolis – Eagle Creek
Severe Weather


March started off quickly with severe weather impacting the region on March 2. A powerful area of low pressure strengthened rapidly as it moved across Indiana into Michigan during the afternoon. Strong winds associated with the system combined with warm and moist air to generate severe thunderstorms across central Indiana. Much of the severe weather was large hail, with a few reports of damaging winds. This event however, will be most remembered for the significant tornadoes that impacted southern Indiana, Kentucky and southwest Ohio. Across far southern Indiana, numerous tornadoes struck, causing extreme destruction to several towns. For additional information on March 2, visit the link below: http://www.crh.noaa.gov/ind/?n=march2_2012severe#otherlinks

Additional severe weather events impacted central Indiana on the 17th, 23rd and 30th. The predominant type of severe weather from each of these events was large hail, with some reports of damaging winds. The Indianapolis International Airport recorded its highest wind gust of the month at 59 mph on the evening of the 17th as a severe thunderstorm passed through. On the 23rd, a long lived mini supercell tracked from Martin County northeast through Bloomington, Shelby County and the southeast Indianapolis metro, continuing northeast through Muncie. This storm produced a wall cloud and funnel cloud in the Bloomington area, and persistent hail that generally ranged from pea to quarter size throughout much of its lifespan. Golf ball size hail occurred in Muncie after the storm briefly intensified. Maybe most impressive, this storm dropped excessive amounts of small hail throughout northwest Shelby County, causing it to collect to the depths of 3 to 4 inches deep along Interstate 74 and other roads in the vicinity of Fairland. Interstate 74 was closed for an extended time period during the early morning of the 24th as county officials needed to use snow plows to get the remnant hail off the road. 



There were just a few severe weather events that impacted central Indiana during the month of April. On the evening of April 1, two small supercells developed north of Indianapolis in the vicinity of a frontal boundary. The storms moved quickly southeast, across the northern and eastern portions of the Indianapolis metro area, as well as Hancock, Decatur, Rush and Shelby counties, producing large hail up to the size of ping pong balls throughout.
Severe weather did not return to central Indiana until the last few days of the month as a nearly stationary boundary meandered across the Ohio Valley. A thunderstorm complex tracked from eastern Missouri, eastward across southern portions of Illinois and Indiana during the late afternoon of the 28th. These thunderstorms moved across the lower Wabash Valley, producing damaging wind gusts and large hail from Vincennes eastward to near Bedford. A 90 mph wind gust was reported in Washington, along with hail up to ping pong ball size. Thunderstorms again moved through central Indiana on the afternoon and early evening of the 30th. These storms remained subsevere, producing wind gusts to around 50 mph which did cause a few downed trees.
A nearly stationary frontal boundary across the region produced periodic showers and thunderstorms throughout the first week of the month. The bulk of the severe weather took place on the 1st as a strong disturbance moved through central Indiana. Thunderstorms impacted areas mainly south and east of Indianapolis during the afternoon, producing damaging winds and large hail. Wind gusts over 70 mph were recorded in Decatur and Henry Counties with thunderstorms. A weak EF0 tornado developed near Cory in Clay County. Focus then shifted to a supercell that moved into the northern Wabash valley during the evening. This storm produced hail, numerous wall clouds, funnel clouds and a couple of tornado sightings across eastern Illinois and into western Indiana. The storm continued to track east-southeast, producing an EF0 tornado near Yeddo in Fountain County and an EF1 near New Ross in Montgomery County. This supercell eventually weakened as it approached the Indianapolis metro area.
Additional strong to severe thunderstorms occurred on the evenings of the 4th, and 6th, and the afternoon and evening of the 7th. Flooding occurred in Ellettsville on the evening of the 7th, as Jacks Defeat Creek rose rapidly after three inches of rainfall fell across western Monroe County. A few homes were evacuated as a precaution near where the creek crosses State Route 46. Scattered thunderstorms developed in advance of a weakening cold front on the 20th and 21st, producing small hail, gusty winds and locally torrential rainfall.

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