The Local Climate of Carrollton, Texas

Overview of Carrollton’s Climate

Carrollton has a humid subtropical climate, with hot summers and mild winters. Located in North Texas, Carrollton’s climate is influenced by its inland location away from the moderating effects of the Gulf of Mexico.

The city experiences seasonal variations in temperature and precipitation. Summers are long and hot, while winters are short and mild.

The hottest months are July and August with average highs of 96°F (36°C), while the coldest months are January and February with average lows of 36°F (2°C).

Temperatures

Temperatures in Carrollton can vary widely over the course of the year. Here is an overview of average temperatures:

• Summer Highs (June – August): Average high around 96°F (36°C)
• Winter Lows (December – February): Average low around 36°F (2°C)
• Record High: 113°F (45°C) on June 28, 1980
• Record Low: -7°F (-22°C) on February 12, 1899

The city sees 100 days per year with temperatures above 90°F (32°C) and around 15 days per year where temperatures stay below freezing.

Diurnal Temperature Variation

There are often large differences between daytime highs and nighttime lows in Carrollton. In summer, overnight lows only drop to around 75°F (24°C), while winter nights can plunge below freezing even when daytime highs are in the 50s°F (10s°C). This diurnal variation is most extreme in spring and fall.

Precipitation

The majority of precipitation falls from April through October in the form of rain from thunderstorms. Here are some key precipitation statistics:

• Average Annual Rainfall: 37 inches (940 mm)
• Wettest Month: May (4.4 inches or 112 mm on average)
• Driest Month: January (1.8 inches or 46 mm on average)
• Average Annual Snowfall: 2.2 inches (5.6 cm)
• Heaviest 1 Day Rainfall: 8 inches (203 mm) on October 17, 2018

Droughts can occur when rainfall totals are less than 30 inches per year, which happened in 10% of years from 1981-2010. Severe thunderstorms can bring heavy rain and flooding, while winter storms occasionally bring freezing rain, sleet, or snowfall.

Growing Season Rainfall

The majority of precipitation occurs during the growing season from April to October, which helps support agriculture in the area.

During winter and early spring, precipitation is lighter but crucial for providing moisture ahead of the growing season. Hail sometimes accompanies severe spring thunderstorms and can damage crops.

Flood Risk

Urban flooding occurs in Carrollton when heavy rainfall overwhelms local drainage capacity. Some major transportation routes are prone to flooding during extreme rain events, including:

• Interstate 35E
• President George Bush Turnpike
• portions of Truman Street, Hebron Parkway, Keller Springs Road

Check for flood alerts and road closure notices during severe storms. Do not attempt to drive through flooded roads.

Severe Weather

As part of Tornado Alley, Carrollton is vulnerable to a variety of extreme and severe weather:

Thunderstorms

• Frequent from March to November, peaking in May
• Main risks are lightning, hail, high winds, flash flooding
• Around 30 thunderstorm days per year on average

Tornadoes

• Part of Texas Tornado Alley with higher tornado frequency
• Tornado season is March through June
• One of higher risk areas in Dallas-Fort Worth metroplex
• Historical tornadoes up to EF4 strength

Hail

• Size of golf balls or larger in some past hailstorms
• May accompany severe spring thunderstorms
• Causes damage to cars and buildings

Winter Storms

• 1 to 2 winter storms per year with snow and ice
• Generally minor overall impacts
• Can disrupt travel, knock out power

Historical Severe Weather Events

Some significant past severe weather events in Carrollton include:

• EF3 tornado in April 1957 causing widespread damage
• Softball-sized hail during April 2006 storms
• 1993 ice storm leaving 250k in DFW without power
• Winter storm in February 2021 dropping 8 inches of snow

Be prepared by having a family emergency plan and assembling disaster supplies like flashlights, backup power options, blankets, medicine, and non-perishable food.

Climate Influences and Land Features

What influences and controls Carrollton’s humid subtropical climate? What land features or weather factors shape local weather?

Inland, Mid-Latitude Location

At 33° North latitude, Carrollton lies in the mid-latitudes, far from moderating oceanic influences. As an inland location in North Texas, weather systems often sweep down the Great Plains bringing extremes of heat, drought, and severe storms. Carrollton lacks the immediate climatic influence of the Gulf of Mexico.

Position in Tornado Alley

Carrollton’s position within the so-called Tornado Alley means more frequent severe spring storms and tornado outbreaks. When cold, dry air from Canada collides with warm, humid air from the Gulf Coast, it can spark powerful thunderstorms and tornado development.

Elevation and Terrain

With an elevation of around 550 feet (168 meters) above sea level on generally flat topography, Carrollton does not have any significant terrain features affecting local climate. There are modest elevation gradients down toward the Trinity River basin to the west.

Urban Heat Island Effect

Built up urbanization introduces heat sinks across concrete-heavy urban and suburban zones. Asphalt roads, sidewalks, parking lots, and buildings retain daytime heat and gradually release heat during the nighttime hours. This can make urban heat island areas several degrees warmer overnight.

Regional Wind Patterns

Prevailing wind flows, storm tracks, and seasonal fronts influence Carrollton’s temperature and precipitation patterns over the course of the year:

Warm Season (March to September)

During summer, winds prevail from the south bringing warmer and more humid air masses up from coastal regions. Easterly winds off areas like Louisiana also transport moisture. Sea breezes sometimes penetrate further inland during heat waves for slight cooling.

Cold Season (October to February)

As cold fronts move down from the north more frequently during winter, northerly winds predominate, delivering periodic blasts of cold, dry air. The dryline wind shift line sets up just west of the region as a boundary between eastward moisture flow and dry west winds.

Transition Seasons (Early Spring, Late Fall)

During the spring and fall shoulder seasons, Carrollton lies in more of a battleground between competing air masses, leading to higher volatility and severe storm potential. Complex wind field changes occur with passing weather fronts and pressure systems.

Local Microclimates

Within Carrollton’s broader humid subtropical climate zone exist smaller-scale microclimates based on elevation, urban density, proximity to waterways, and amount of greenery.

Microclimate Variations

Parts of Carrollton may exhibit localized variations in top climate factors like:

• Average temperatures
• Frequency of 100°F+ days
• Intensity of the urban heat island effect
• Nighttime temperature cooling rates
• Total seasonal rainfall
• Snowfall accumulations

Higher Elevations

Slightly cooler temperatures prevail at topographically higher elevation zones toward the eastern side of Carrollton in the 600+ feet range. During summer heat waves or inversions, cooler air tends to sink to lower basins and valleys.

Trinity River Basin

The bottoms of the Trinity River basin feature more humid conditions given moisture retention down in the valley. Sections of floodplain also have deeper moisture reserves that aid vegetation growth during drought periods. Pockets are slightly warmer on average.

Floodplain Wetlands

Isolated floodplain wetlands scattered along tributary creeks experience their own unique wet foliage microclimates thanks to idyllic, closed canopy conditions. Dense vegetation cover also boosts humidity while lowering air and water temperatures.

Parks and Greenbelts

Heavily vegetated community parks, golf courses, and greenbelt zones enjoy localized cooling from increased shade and evapotranspiration across lakes, ponds, fountains, lawns, gardens, and tree groves. These urban oases can be 5°F cooler on hot summer afternoons.

Seasonal Variations and Events

Carrollton’s humid subtropical climate produces distinct seasons with different temperature and precipitation norms as well as seasonal events and happenings tied to the changing weather.

Winter (December to February)

Winters are typically short and mild across most of Texas including Carrollton, yet extreme arctic cold outbreaks can still occur:

Average High: 57°F (14°C)

Average Low: 36°F (2°C)

• Dormant period for vegetation
• Light precipitation; occasional snow/ice storms

Spring (March to May)

Spring brings warming temperatures and the threat of severe thunderstorms:

Average High: 77°F (25°C)

Average Low: 55°F (13°C)

• Wildflower blooms
• Severe weather season begins
• Flash flooding potential
• Tornadoes
• Hail
• Peak rainfall in May

As temperatures quickly rise while clashing with late-season cold snaps, the atmosphere becomes increasingly unstable, sparking severe thunderstorm development across North Texas.

Vibrant wildflower displays color the countryside starting in March as bluebonnets, Indian paintbrushes and other flowers blanket fields and roadsides. But enjoy quick before they wilt under the intensifying springtime heat.

Spring Severe Weather Safety Tips

Be alert to sudden changes in weather conditions, darkening skies, or warnings from local authorities. Seek shelter immediately if a tornado or severe storm is approaching:

• Identify closest tornado shelters
• Monitor TV, radio, mobile phones for alerts
• Avoid windows, vehicles, mobile homes
• Cover in interior room or basement

Summer (June to August)

The hot and humid months of summer arrive with intense heat waves:

Average High: 96°F (36°C)

Average Low: 75°F (24°C)

• Peak heating degree days
• High humidity as heat index tops 105°F (41°C)
• Heat waves and advisories
• High water usage and drought risk
• Local burn bans

The arrival of summer brings the year’s longest daylight hours and peak solar intensity. Coupled with humid southerly winds, summertime heat dominates local weather conditions and events.

Heat indices measuring combined heat and humidity levels routinely exceed 105°F (41°C), signalling dangerous conditions for outdoor activities. Heat cramps, exhaustion and strokes are top summer weather risks.

Water usage also soars over the summer months, depleting area reservoirs and potentially triggering outdoor water restrictions if drought conditions develop. Local burn bans prohibiting outdoor fires may also be implemented during stretches of heat and drought.

Top Summer Weather Safety Tips

Beat the Texas heat and stay cool with these precautions:

• Hydrate frequently
• Limit prolonged outdoor exposure
• Wear lightweight, light colored clothing
• Schedule intense activities in early morning/evening
• Monitor local heat advisories and indices

Fall (September to November)

Pleasant autumn weather arrives before winter’s cold takes hold:

Average High: 81°F (27°C)

Average Low: 57°F (14°C)

• Lower humidity
• Fall foliage colors
• Second severe weather season
• Occasional snow potential late

A welcome drop in humidity accompanies the gradual cooldown into fall. A second severe weather season kicks up in October as colliding air masses spur autumn storms with high winds, hail, lightning and isolated tornadoes.

Vibrant fall foliage takes hold across deciduous trees and shrubs starting in late October. Red and gold leaves stand out most boldly against urban backdrops. But enjoy the colors quickly before winter defoliation.

As winter nears in November, northern cold fronts sometimes meet up with Gulf moisture to generate the season’s first snow or wintry mix potential.

Most years though, accumulating snow holds off until the winter months across the majority of the Dallas-Fort Worth metro region including Carrollton.

Fall Lawn Care

Transition lawn care steps like aerating, overseeding, fertilizing and adjusting irrigation systems help lawns recover from summer stress and prepare for cooler months ahead. Monitor soil moisture levels heading into winter dormancy periods.

Annual Events and Celebrations

Changing seasons across Carrollton also usher in beloved annual happenings, festivals and events for the local community:

Winter

• New Year’s Eve fireworks shows
• Chinese New Year festivals
• Annual Martin Luther King Jr. Day march

Spring

• Easter egg hunts
• Annual St. Patrick’s Day parade
• Cinco de Mayo festivals

Summer

• Red, White and Blue Blast July 4th celebration at Josey Ranch Lake Park
• City birthday festival in late August
• Labor Day fireworks finales

Fall

• Annual Oktoberfest beer celebrations
• Pumpkin festivals and patch tours
• Veterans Day memorial ceremonies

Climate Change Impacts

Like locations worldwide, Carrollton’s climate patterns are gradually being altered by global climate change, driving long-term shifts in average conditions, extremes, and seasonal impacts.

Observed Local Changes

Analyzing weather records over past decades reveals steady changes consistent with regional and global climate change:

• Average temperatures up 1.5°F since 1970
• More frequent 100°F days
• Longer growing season by 2+ weeks
• Greater annual precipitation variability
• More heavy rain events

Projected Climate Changes

Scientific climate models point to Carrollton experiencing the following climate shifts through coming decades:

Hotter Summers

• Average summer temps rising 6+°F by 2050
• Heat waves becoming more intense and frequent
• Growing cooling demands

Altered Rainfall Patterns

• Periods of intensified drought broken up by heavy rain
• Greater flood risk with heavy downpours
• straining of storm drainage systems

At the Extremes

• More 100°F+ days above the current average of nearly 100 days
• Rapid day-to-night temp shifts

Monitoring local climate data and trends year-over-year will reveal real-time shifts as average conditions depart from the historical baseline.

Conclusion

Carrollton’s humid subtropical climate brings the heat of summer and storm threats of spring, while allowing for mild winters.

Microclimate variations exist across terrain zones, elevation levels and urban density. Climate change drives hotter summer extremes and amplified rainfall patterns. Tracking the numbers reveals the climate narrative over time.