South Dakota Weather History and Trivia
May

May 1 -

Which state has the warmer all-time high temperature record...Alaska or Hawaii? Believe it or not, it is a tie. The warmest temperature ever recorded in Alaska is 100 degrees F which occurred June 27, 1915 at Fort Yukon. The warmest temperature on record for Hawaii is also 100 degrees F which was set on April 27, 1931 at Pahala. Record low temperatures for the state are, of course, a different story. The United States record low temperature of -80 degrees F was recorded January 23, 1971 at Prospect Creek, Alaska. By contrast the coldest temperature on record in Hilo, Hawaii is 53 degrees F set in February 1962.

May 2 -

On May 2nd, 1984 strong thunderstorm winds did damage just northwest of Pierre. The strong winds lifted a trailer into the air and hurled 50 yards before crashing it back into the ground...destroying the trailer. During its brief flight the trailer was lifted high enough to damage the upper sections of a home.

May 3 -

Hail often falls in swaths or streaks beneath thunderstorms, with paths typically 5 miles long and one-half mile wide. The world's "hail belts" are generally found at mid-latitudes, often downwind of mountain ranges. The high plains of the United States and Canada are among the areas that receive the most hail in the world.

May 4 -

On May 4th, 1967 the temperature dropped all the way to 17 degrees F. That is the coldest temperature on record for the month of May in Sioux Falls.

May 5 -

Heavy rains...snow...and severe weather struck the Black Hills area on May 5th, 1975. Heavy rains totaled two to five inches in the northern Black Hills flooding many streams. Higher elevations such as the Lead area received over a foot of snow. While heavy rains and snow pounded the Black Hills the surrounding plains had to contend with severe weather. Rapid City narrowly missed being struck by a tornado as the storm's damage path began about 2 miles east of Rapid City. The Rapid City airport did report a gust of 53 miles an hour with Ellsworth Air Force Base receiving a gust to 70 miles an hour. The tornado did cause severe damage to farm buildings in the Tilford area.

May 6 -

Ever wonder how far a lightning discharge can travel? If the lightning is a cloud-to-ground bolt, then the travel distance is limited by the distance from the inside of the cloud to the ground, which is usually under 10 miles. Cloud-to-cloud or intracloud discharges my reach for 100 miles or more in rare cases.

May 7 -

May 7, 1993 severe weather erupted across the tri-state area ahead of an approaching cold front. Tornadoes, large hail, strong winds, and flash flooding all affected the area on this one night. One of the numerous tornadoes on that day traveled north near I-29 destroying a farmstead and tossing vehicles. The tornado destroyed a large barn silo, and numerous outbuildings just north of Beresford. The tornado overturned an 11,000 lb. tractor, but that was only a warmup for the 34,000 lb. semi-truck that the storm lifted off the ground and threw into the ditch... the storm also blew several cars off of an exit ramp.

Strong thunderstorm winds estimated at over 100 miles an hour destroyed an apartment building, 5 mobile homes, 15 garages, 16 vehicles, and damaged many other homes and vehicles in the Brookings area. Across southwest Minnesota several tornadoes and straight line wind gusts did damage. Rainfall amounts of 2 to 7 inches in less than three hours were common across southeast South Dakota and southwest Minnesota causing flash flooding. Several hundred homes and businesses were flooded across southwest Minnesota causing $1.6 million dollars in damage in Rock County alone.

May 7 -

May 7th, 1967 the eastern half of South Dakota was choked by a dust storm. Strong winds which occasionally exceeded 60 miles an hour whipped dust high into the air reducing visibilities to near zero at times. The low visibilities were responsible for many accidents on area highways. A large amount of top soil was eroded and carried away by the wind in some areas erosion was so bad that small grain crops had to be re-seeded.

May 8 -

When you look a flash of lightning the bolt appears to be quite wide, but in actuality most lightning bolts are not much thicker than a pencil. However, lightning can be quite long with vertical strikes stretching 5 to 10 miles while horizontal channels can reach over 100 miles in length.

May 9 -

Strong thunderstorms produced high winds and copious rainfall amounts in eastern South Dakota on May 9th, 1986. The strong winds blew down an overhang and porch near Brandon, but more impressive were the rainfall amounts. Two to four inches of rain were common over much of eastern South Dakota including a 7.5 inch total at Redfield (in Spink county). The heavy rainfall caused extensive flooding, with Walworth and Potter counties reporting the most damage. In those counties many roads and several bridges were washed out. In Lyman county a dam on Lake Byre broke leaving water waist deep in the town of Kennebec.

May 10 -

On May 10th through the 12th, 1991 heavy rainfall led to devastating flash floods in the southern Black Hills. Rain amounts ranged from four to ten inches in most locations. The runoff poured into creeks and rivers, rapidly driving them out of their banks. The city of Oral was the hardest hit as flood waters carried several houses a few hundred feet from where they originally stood. Many roads, culverts, and bridges were completely washed out by the floods causing over $1 million dollars in damage.

May 11 -

A late Spring snowstorm hit the western third of South Dakota on May 11th and 12th, 1983. Snow amounts ranged from 3 to 10 inches and in some areas the snow was accompanied by thunder, lightning, sleet, and hail making for an interesting mix of weather. The heaviest snow amounts fell in the northern Black Hills although some areas in the plains had strong winds creating drifts high enough to make roads impassable.

May 11 -

Numerous tornadoes touched down in southwest and west central South Dakota on May 11th, 1991 causing considerable damage. Strong winds and hail swept through the Custer National Forest damaging up to 2,500 acres of trees. However, things were much worse in the Rapid City area. Numerous tornadoes touched down in the Rapid City area. One tornado damaged several homes and destroyed, at least, nine mobile homes five miles north of Rapid City. A larger tornado, reportedly over 1/4 of a mile wide, and packing winds estimated between 150 and 200 miles an hour just 5 to 10 miles north of Rapid City destroyed 9 homes and damaged 150 others. The storm caused many injuries, but no deaths. Also, at least seven tornadoes were spotted in the Edgemont area although damage was light.

May 12 -

On May 12th, 1984 severe weather erupted across northeast South Dakota. A tornado touched down just northeast of Clark (in Clark County) and cut a path 25 miles long into Codington County. The tornado moved southeast and, at times, was an amazing three- quarters of a mile wide. The storm moved through southwest sections of Henry (in Codington county) where it split into two separate tornadoes which moved different directions. One moved northeast and quickly dissipated while the second continued its path of destruction to the southeast.

On its southeast trek the tornado destroyed eleven barns, twenty-three sheds, six homes, one mobile home, seven garages, eight grain bins, as well as, machinery and hundreds of trees. The storm also wrapped a small plane around a pole. Areas along the storm path reported hail from golf ball to grapefruit size with some areas in Henry having the hail pile up to 15 inches deep.

May 13 -

How's this for heavy rain? On May 13th, 1982 a thunderstorm dumped 5 inches of rain in less than one hour just south of Platte (in Charles Mix county)! The runoff from the rain was sufficient to move a 54 foot cultivator up against a fence.

May 13 -

The latest significant snow (that is a snowfall of 2 inches or more) for Sioux Falls occurred on May 13, 1943 when Sioux Falls reported 2 inches of snow.

May 14 -

Is it possible that cities affect the frequency that lightning occurs? It's possible. Recent research suggests that lightning frequencies over and downwind of many Midwestern cities can be 10 to 20% higher than for surrounding areas.

May 15 -

On May 15th, 1991 a series of slow moving thunderstorms moved over Bennett county in South Dakota. Not only did five to six inches of rain fall in the Martin and Tuthill area, but marble to golf ball size hail fell for an extended period of time. So much hail fell that it actually piled into drifts as high as 6 feet.

May 16 -

The highest average annual wind speed at any recording station in the United States is on Mt. Washington where the average wind speed is 35 miles an hour. You think it's windy here in the plains...Mt. Washington (in New Hampshire) once averaged winds at 128 miles an hour for an entire day and 70 miles an hour for a month!

May 17 -

Research on lightning deaths finds that most fatalities occur at the time that the storm appears to be ending. During the height of a thunderstorm most people are inside seeking protection from the rain. For about a 10 minute period after the rain ends (sometimes longer) and even when it seems that the sun is coming out...lightning can still be quite a threat. People begin to head back outdoors and these late lightning strikes prove very dangerous.

May 18 -

On May 18th, 1977 residents of western South Dakota experienced some rough weather. Golf ball sized hail and wind gusts to 87 miles an hour ripped through Philip (in Haakon county). The hail was quite intense and drifted to one and a half feet deep. The storm heavily damaged several aircraft at the Philip airport. Also, baseball sized hail was reported near Harrington (in Bennett county) with winds over 60 miles an hour throughout the area causing only minor damage.

May 18 -

The latest measurable snow on record in Sioux Falls occurred on May 18, 1968 when .7 of an inch of snow fell.

May 19 -

With the ground in Black Hills already saturated from heavy rains the previous week, developing thunderstorms were not a welcome sight on May 19th, 1982. The thunderstorms produced additional heavy rains including 3.58 inches at Spearfish...3.32 inches at Cheyenne Crossing...and .82 of an inch in twelve minutes at Hot Springs. With Flash Flood Warnings in effect for much of the area water came out of the banks of many streams causing widespread damage in the Hills. A diversion Dam broke at Spearfish causing a mud slide to cover some roads. In Deadwood the main water line broke leaving the city temporarily without water. Homes were evacuated at Nisland, Hot Springs, and Bridger. Damage throughout the Black Hills included washed out bridges, flooded basements, several breached dams, and roads completely washed away.

May 20 -

Severe weather erupted across central and western South Dakota on May 19th and 20th, 1974. On the evening of May 19th, 1974 thunderstorms developed across the central sections of the state dropping numerous tornadoes although damage was minimal as the storms were in largely unpopulated areas. However, on the 20th strong winds toppled several structures, including a drive- in theater screen, across Meade county. Also on the 20th, softball sized hail fell in Kennebec doing tremendous damage to area windows.

May 20 -

Unfortunately for area residents, the little town of Codell, Kansas was hit by a tornado in three consecutive years 1916-1917 and 1918. While that is remarkable in itself, the fact that all three years the tornadoes struck the town on the same day, May 20th, is truly bizarre.

May 21 -

Heavy rains inundated portions of southeast South Dakota on May 21st, 1982. Five and one-half inches fell at Yankton over the course of 4 hours...while eight and one-half inches fell in two hours southwest of Parkston (in Hutchinson county). Not to be outdone Avon (in Bon Homme county) picked up 1.80 inches in only 25 minutes. The heavy rains and rapid runoff from the storms washed out many roads in the area.

May 22 -

May 22nd, 1993 is a day that will be remembered in Sioux Falls for many years. Nearly stationary thunderstorms dumped five to seven and one-half inches of rain on the southwest side of Sioux Falls causing major urban flooding. At least 200 basements were flooded by water and sewage as storm and sewer systems backed up. Water came up to the roofs of cars in the Empire Mall area. Nearly 3000 customers in Sioux Falls lost power due to the flooding. Quarter sized hail fell for up to 1 1/2 hours continuously in some areas in southwest Sioux Falls causing considerable damage to hundreds of roofs, trees, and gardens. Thousands of cars received extensive hail damage. The storm seemed to serve as a precursor for the wet months and extensive flooding that occurred in the summer of 1993.

May 22 -

On May 22nd, 1975 thunderstorms packing extremely high winds raked portions of eastern South Dakota. Strong winds and hail hit several counties in the northeast portion of the state with a few funnel clouds being sighted. But, the real weather was going on in the southeast where Mitchell reported a gust of 75 miles an hour and Yankton was blasted with a 103 mile an hour gusts. The strong winds toppled many trees and farm structures in the Yankton area.

May 23 -

Bigger hailstones, of course, fall faster than small hailstones. If you've ever been amazed at the damage caused by a brief hailstorm, you won't be when you hear how fast the stones are falling. A pea-size hailstone falls at approximately 22 miles an hour. The golf ball sized stones will plunge earthward at around 60 miles an hour while the massive baseball sized stones fall at a rate of around 100 miles an hour.

May 24 -

Many towns think that they are safe from tornadoes because of a local hill or a nearby river. This is actually a poor assumption. Tornadoes have been tracked crossing up and over mountain ridges as high as 3000 feet. Also, at least, 30 significant tornadoes have crossed the Mississippi River, with hundreds of other tornadoes crossing other major rivers.

May 25 -

During the afternoon of May 25th, 1985 thunderstorms developed along the east side of the Black Hills. The storms produced quite a bit of lightning and over the course of 2 hours started 18 small fires in the Black Hills. Fortunately, most of the fires were small and easily contained. One unfortunate fire fighter was struck by lightning as he was helping to extinguish a blaze that burned some 50 acres of grassland and forest. Thankfully, the man lived, but he did suffer several broken bones, burns, and major damage to his ears. The strike was so powerful that a man standing over 150 feet away was dropped to his knees.

May 26 -

On May 26th, 1992 a widespread frost and hard freeze hit most of South Dakota except for the southeast. Record low temperatures were set at Huron with 28 degrees...Pierre at 29 degrees...and Rapid City and Aberdeen at 30 degrees. The coldest temperature in the state was 18 degrees near Wessington Springs. The widespread freeze was, of course, hard on the agricultural community where $14 million dollars in crop losses were estimated.

May 27 -

On May 27th, 1991 thunderstorms erupted across southwest South Dakota during the evening and made their way into southeast sections of the state by the early morning hours of the 28th. In the southwest, already saturated ground and swollen creeks were drenched with 4 to 6 inches of rain. The rain produced flash flooding that damaged many roads and several bridges.

In the east central and southeast the storms produced gusty winds and large hail. Storms on May 27th and 28th, 1991 had reported wind gusts of over 80 miles an hour with numerous reports of over 60 miles an hour. However, the real threat with these storms was the hail. Over 1000 nesting birds were killed by falling hail at La Creek Refuge in Bennett county. Softball size hail was reported just north of Artesian in Sanborn county, and near Arlinton in Kingsbury county. The hail completely destroyed a grain bin near Arlington. Many areas had golf ball size hail or larger. Many homes had windows knocked out and roofs damaged. The storms produced millions of dollars in damages.

May 28 -

It always seems like its always cloudy on the weekends or on the day you have an outdoor activity scheduled. In reality, most of South Dakota, southwest Minnesota, and northwest Iowa receive between 60 - 70% of the possible hours of sunlight through the course of the year. However, portions of the north central and northeast South Dakota only receive between 50 and 60% of the possible hours of sunlight.

May 29 -

Do you know what the wettest month on record is for Sioux Falls? It occurred way back in May of 1898 when 9.42 inches of rain fell. That's over 1/3rd of the precipitation in an average year. The second wettest month for Sioux Falls was August 1932 when 9.33 inches of rain filled the gauge.

May 30 -

An amazing 17 inches of rain fell in a nine day period of time ending on May 30th, 1982 in the town of Avon, South Dakota (in Bon Homme county). This, of course led to major flood problems in the area. Krug's lake, located 1 mile south of Avon, is normally dry. Not only did the lake fill up, but it also drained into the south side of the town after a hastily constructed dike gave way. Many dwellings in the town ended up being completely surrounded by water.

May 30 -

The highest temperature on record for Sioux Falls in the month of May occurred on the 30th in 1934 when the mercury climbed to 104 degrees.

May 31 -

Believe it or not, the latest in the season that snow has fell in Sioux Falls is May 31st. On May 31, 1954 the Sioux Falls observing station reported a trace on snowfall.


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