Index
Site and Situation
Site and situation are keys to understanding Kentucky's climate and its role in the state's economy. Kentucky is centrally situated in the eastern half of the United States. It lies midway between the Gulf of Mexico to the south and the Great Lakes to the north and between the Atlantic Coast to the east and the Great Plains to the west. Kentucky site is characterized by a physical landscape covering more than 40,000 square miles and extending more than 400 miles from the Mississippi River in the west toward the Appalachian Mountains in the east. It is about 175 miles at its Greatest extent from north to south and it narrows to the west. Elevation increases from less than 400 feet above sea level along the Mississippi River to higher than 4,000 feet along the southeast. However, 75% of the state lies below 1,000 feet above sea level, and 99% percent is less than 2,000 feet in elevation. With the exception of a small area along the western margin of Kentucky that drains directly into the Mississippi River, Kentucky's nearly 90,000 miles of streams and rivers drain to the north and west into the Ohio River.
 
Regional Landscapes
Kentucky is a state of diverse regional landscapes. Physical proceess have shaped distinctive landforms, and people have used these in a variety of ways to make a living. The influence and importance of climate varies with the physical and economic character of these regional landscapes The Jackson Purchase Region of far western Kentucky includes alluvial plains and small hills. Low lying areas strecting south and east from the Ohio and Mississippi rivers are nearly flat and thus poorly drained. labkes, pponds and other welands are common Local relief is generaly less than 100 feet. the soil is fertile, and agriculture helps to sustain the regions small rural communities. Corn, soybeans, and winter wheat are the dominant crops. Oaducha sitated along the Ohio River, is the region's larges industrial and commercial center.

The Western Kentucky Coal Field Region lies east of the Jackson Purchase It is part of a basin that reaches southward from Illinois and Indiana and is endowed with coal and oil resources. Relief increases toward the margin of the basin, and much of this area is forested. Alluvial deposits become prominent in proximity to the Ohio River. As in the Jackson Purchase, the nearly flat land is poorly drained and wetlands are evident. Fertile soils support extensive production of corn and soybeans. Agriculture and mining have supported the growth of many rural communities. The cities of Owensboro and Henderson, both located along the Ohio River, are primary centers of business and industry.

Kentucky is perhaps best known for its Bluegrass Region. Located in north central Kentucky, the core of the Bluegrass is a gently rolling karst plain characterized by sinkholes, sinking stream and springs. The region's limestone-purified water is recognized as a key location factor for Kentucky's distilleries. Weathering of limestone has prodcued the state's most fertile soil, and the horse farms sprawling across rich pasturelands are a Kentucky icon. Relief increases gradually and the soil becomes less fertile twoards the margin of the Bluegrass. Tobacco isalso an important source of income for farmers throughout much of the region. The Knobs Region, identified by disperesd, often conical hills that have steep slopes but rise only about 500 feet above the surrounding plain, surrounds the Bluegrass. The City of Lexington lies in the heart of the Bluegrass while the outer Bluegrass inculdes the Ohio River cities of Louisville and Covington. This is the most highly urbanized and industrialized region in Kentucky.

Farther to the east, the Eastern Kentucky Coal Field Region is distingushed by its more rugged terrain. Most of the region lies on the Appalachian Plateau that rises gradually from the west toward the Appalachian Mountians. The plateau has been carved by water to form a landscape distinguished by a maze of hills, valleys and hollws. The hills are less than 2,000 feet in elevation, and local relief is several hundered feet. Pine Mountain trends across the south eastern margin of Kentucky where the plateau reaches the Appalachian Mountains. Kentucky's highest point is 4139 feet, is the peak of Black Mountain along the border with Virginia. The Eastern Kentucky Coal Field is well endowed with natural resources including abundant coal deposits, natural gas, and extensive forests that support the region's economy. Strip mining has significantly altered the landscape in some areas. Forestes include a mixture of hardwood and softwood species. Agriculture includes a mix of tobacco, corn, hay, and pasture but is practiced on a very limited scale. Soils are not praticularly fertile, and only small areas of flat land are avalible for cultivation. This region is also the least industrialized . Ahsland, the largest city in the region, is located along the Ohio River. Cities located througut the region are small and largely confined to narrow valleys and more gently sloping hillsides.

The Pennyroyal Region stretches across southern Kentucky from the JAckson Purcahse to the Bluegrass and Eastern Kentucky Coal Field. The Dripping Springs Escarpment of the Pennyroyal encircles much of the Western Kentucy Coal Field and falls onto a karst plain. Sinkholes, sinking streams, and springs are characteristic of the rolling landscape. Mammoth Cave, the world's longest cave system is located in the region. Much of the escarpment is forested, while the karst plain supports a variety of agricutral uses. In its western and southern extent, corn,soybeans and winter wheat are grown. Farther east and north, patureland and hay become more common, and siginficantly less land is devoted to grain production. Tobacco is an important cash crop throught much of the region. Bowling Green, a diverfied city that capitalizes on its location between Louiville and Nashville, Tennessee, is the Pennyroyal's largest city. Hopkinsville and a number of other smaller cities are dispersed throught the region. Tourism is important in the Mammoth Cave area, the Land Between the Lakes region located at the westen extent of the region, and Lake Cumberland located near the eastern extent.
 
Climate
The climate of Kentucky reflects the interplay of several locational influences. Kentucky's inland location contributes to a contiental influnces which acting alone tends to produce a large seasonal temperature range between summer and winter. Meanwhile, its position north of the gulf of Mexico contributes a tropical marine influence that moderates temperatures and yields ample precipitation. Kenucky's mid-latitude position places it in a region where weather can be highly variable. While prevailing surface winds are southerly and light, upper level westerly winds steer frontal systems across the state. These systems bring warm,moist air from the south,followed by cooler and drier air from the north. At a broder scale, Kentucky's climate is influenced by ineractions involving teh oceans and atmosphere. While these influences originate thousands of miles away, thay may contribute to significant varations in Kentucky's cliamte on a seasonal or annual time frame.

Mean annual temperature ranges from 53 F in the northeast to 59 F in the southwest but there is significant seasonal variation in temperature. Summer days are Typically sunny warm and humid. Most areas of the state recive more than 60 percent of available sunshine during summer. the average daily high temperature for july increases from about 86 F in the east to 90 F in the west. High temperatures exceed 90 F an average of 20 days per year in the north and east and 40 or more days in the south and west. Temperatures occasionaly exceed 100 F. The passage of frontal systems is less frequent durring summer, so weather patterns are typically more persistent. But when they do arive, cold fronts bring pllesant conditions that may persist for a few days. Winters are rarely harsh. In January average daily high temperatures increase from 338 F in the north to 44 F in the south. Cloudy skies are more frequent in winter, as most areas recive nearly 40 percent of available sunshine. Polar air masses occasionally affect Kentucky for short periods. Temperatures dip below 0 F an average of about fie days in the north and two days in the south. Spring and fall are generally pleasant seasons, though temperatures can change dramatically with the passage of frontal systems. The diurnal temperature range is about 20 F during the summer and winter but increases to near 25 F during the spring and fall, when warm days and cool nights are prevalent.

Kenucky's growing season varies across the state. The average date of the last spring freeze ranges from early April in the southwest to early May in the northeast. Meanwhile, the avearge date of the first fall freeze extends from early October in the northeast to late Ocotober in the southwest. The aveage length of the frost-free period varies from about 165 days in the northeast to 200 days in the southwest, but the average can vary with local topography.

Precipitation is generally plentiful to meet agricultural needs and the needs of municipalities that serve industrial, commercial, and residentail users. Average annual precipitation ranges from 42 inches in the north to 52 inches in the south. Much of the range is due to a strong precipitation gradient during the winter season. Summer precipitation patterns are less pronounced.

Fall is normally Kentucky's dry season, while the spring season is typically the wettest. But precipitation is well distributed throught the year. Thunderstorms are responsible for much of the rainfall during summer, and they often bring intense rainfall that may be highly localized. Rainfall intenseities generally increase twoards the southwest. Rates exceeding one inch per hour are not ususual, and 24-hour totals of five inches or more occur an avearge of about one in ten years at a given location. Meanwhile it is common for a location to go for a period of two weeks or more without mesurable precipitation in the summer or fall. Snowfall is most likely from December to March, but it occasionally occursa as eraly as October or as late as April. Seasonal amounts average from nearly 10 inches in the south to more than 20 inches in the north. Amounts are highly variable from year to year. In some years, a single heavy snowfall event may represent a large precentage of the seasonal toatl. Across southern Kentucky, seasonal totals of less than five incehs are fairly common, while totals of more than 20 inches are infrequent. Northern areas rarely recive less than 10 inches of snow and occasionally recive as much as 40 inches or more. Snowcover seldom persists for than a week in the south or more than two weeks in the north.
 
Natural Hazards
The climate of Kentucky reflects the interplay of several locational influences. Kentucky's inland location contributes to a contiental influnces which acting alone tends to produce a large seasonal temperature range between summer and winter. Meanwhile, its position north of the gulf of Mexico contributes a tropical marine influence that moderates temperatures and yields ample precipitation. Kenucky's mid-latitude position places it in a region where weather can be highly variable. While prevailing surface winds are southerly and light, upper level westerly winds steer frontal systems across the state. These systems bring warm,moist air from the south,followed by cooler and drier air from the north. At a broder scale, Kentucky's climate is influenced by ineractions involving teh oceans and atmosphere. While these influences originate thousands of miles away, thay may contribute to significant varations in Kentucky's cliamte on a seasonal or annual time frame.

Mean annual temperature ranges from 53 F in the northeast to 59 F in the southwest but there is significant seasonal variation in temperature. Summer days are Typically sunny warm and humid. Most areas of the state recive more than 60 percent of available sunshine during summer. the average daily high temperature for july increases from about 86 F in the east to 90 F in the west. High temperatures exceed 90 F an average of 20 days per year in the north and east and 40 or more days in the south and west. Temperatures occasionaly exceed 100 F. The passage of frontal systems is less frequent durring summer, so weather patterns are typically more persistent. But when they do arive, cold fronts bring pllesant conditions that may persist for a few days. Winters are rarely harsh. In January average daily high temperatures increase from 338 F in the north to 44 F in the south. Cloudy skies are more frequent in winter, as most areas recive nearly 40 percent of available sunshine. Polar air masses occasionally affect Kentucky for short periods. Temperatures dip below 0 F an average of about fie days in the north and two days in the south. Spring and fall are generally pleasant seasons, though temperatures can change dramatically with the passage of frontal systems. The diurnal temperature range is about 20 F during the summer and winter but increases to near 25 F during the spring and fall, when warm days and cool nights are prevalent.

Kenucky's growing season varies across the state. The average date of the last spring freeze ranges from early April in the southwest to early May in the northeast. Meanwhile, the avearge date of the first fall freeze extends from early October in the northeast to late Ocotober in the southwest. The aveage length of the frost-free period varies from about 165 days in the northeast to 200 days in the southwest, but the average can vary with local topography.

Precipitation is generally plentiful to meet agricultural needs and the needs of municipalities that serve industrial, commercial, and residentail users. Average annual precipitation ranges from 42 inches in the north to 52 inches in the south. Much of the range is due to a strong precipitation gradient during the winter season. Summer precipitation patterns are less pronounced.

Fall is normally Kentucky's dry season, while the spring season is typically the wettest. But precipitation is well distributed throught the year. Thunderstorms are responsible for much of the rainfall during summer, and they often bring intense rainfall that may be highly localized. Rainfall intenseities generally increase twoards the southwest. Rates exceeding one inch per hour are not ususual, and 24-hour totals of five inches or more occur an avearge of about one in ten years at a given location. Meanwhile it is common for a location to go for a period of two weeks or more without mesurable precipitation in the summer or fall. Snowfall is most likely from December to March, but it occasionally occursa as eraly as October or as late as April. Seasonal amounts average from nearly 10 inches in the south to more than 20 inches in the north. Amounts are highly variable from year to year. In some years, a single heavy snowfall event may represent a large precentage of the seasonal toatl. Across southern Kentucky, seasonal totals of less than five incehs are fairly common, while totals of more than 20 inches are infrequent. Northern areas rarely recive less than 10 inches of snow and occasionally recive as much as 40 inches or more. Snowcover seldom persists for than a week in the south or more than two weeks in the north.
 
Climate & Economy
Kentucky's climate is a valuable natural resource. However like other states, Kentucky is vulnerable to a variety of hazards assosciated with its climate. These hazards pose therats to life and property, and tey can disrupt economic activity.

Thunderstorms are an important element of Kentucky's climate. They can occur throught the year but are most common in warmer months. The number of thunderstorm days averages about 55 in the west and closer to 40 in the east. While thunderstorms are a vital source of rainfall in the summer season, they can also bring servere weather, inculuing damaging winds, hail, and torandoes. Fewer than ten torandoes are recored in most years. Torandoes are most frequent in Aprial, but can occur in any month.

Winter storms producing heavy snow occasionally affect Kentucky. Heavy snow is normally associated with storm systems that orginate in the southwest, are fueled by Gulf moisture, and track toward the northeast. Instead of snow, a winter storm may bring freezing rain that produces significant icing, but shuch events are infrequent. Intense winter storms are sometimes followed by cold waves that bring subzero tempratures.

Flooding can be widespread or highly localied acroos Kentucky. Wiedspread flooding is most common in the winter and spring seasons when moisture-laden frontal systems can drop heavy rains over large ares. Flooding in the late summer and early fall can occur due to the remenats of a tropical cyclone that tracts over the state. Intense thunderstorm precipitation can cause flash flooding.

While flash floods can occur anywhere across the state, they are a greater threat in areas of rough terrain and narrow stream valleys.

Droughts are a recurrent feature of Kentucky;s climate. They occur an aveage of about one year in ten and usually become evident during the growing season when tempratures are warm and the demand for water is high. Since fall is normally a dry season, recovery ussualy dose not occur untill winter and in some cases a drought may persist for more than a year. Droughts often intensifiy during the summer due to a strong Bermuda High, wich blocks the movement of frontal systems accross the state, inhbits the development of thundersorms, and contributes to the intesity of heat waves.