U.S. Fire Administration/National Fire Data Center

The Seasonal Nature of


Fire Incidents in 2000


Topical Fire Research Series, Volume 3 – Issue 6


June 2004 
T O P I C A L F I R E R E S E A R C H S E R I E S


The Seasonal Nature of Fire Incidents in 2000 

June 2004 Volume 3, Issue 6 

Findings 

H In the winter, the majority of the country experiences colder and wetter weather 

conditions, increasing the need for structural heating and producing the peak 

period for heating fires. 

H Warmer spring weather brings people outdoors, producing the peak period for 

total outdoor fires and fires caused by open flame. 

H During the summer, hot weather and reduced precipitation dry out natural 

vegetation, producing the peak period for natural fires. Summer is also the peak 

period for incendiary and suspicious fires, fires associated with fireworks, and 

children playing with fire. 

H Overall fire incidence is at its lowest in the winter as increased precipitation and 

cooler weather reduce the fuel available for outdoor fires and people spend more 

time indoors. 

H The incidence of vehicle fires is relatively constant throughout the year. 

Through decades of study, the incidence of fire has followed distinct patterns and trends that are seasonal in 

nature. Both natural occurrences and human behaviors vary with the seasons, and both are factors that affect the 

causes and damaging effects of fires. Changes in weather and climatological events can lengthen a season or rush 

the onset of a new one. Nevertheless, the individual seasons, and the U.S. population, do present certain fire profiles that are repeated year after year and can, in some measure, be predicted. 

In 2000, an estimated 1.7 million fires in the United States claimed more than 4,000 lives, injured 22,350 

people, and caused $11.2 billion in property damage.1 The three leading causes of fire in 2000—incendiary, cooking, and open flame—are greatly affected by seasonal human activities. This report explores fire patterns by each 

season in 2000; both the changes in incidence and the causes of fire are discussed. For purposes of this report, the 

seasons are measured in 3-month blocks: winter is December through February, spring is March through May, 

summer is June through August, and fall is September through November. 

SEASONAL FIRE PROFILE 

Significant weather events that affected fire incidence in 2000 include a severe winter storm along the east 

coast in January, record high temperatures in the Southwest during May and June, a severe spring and summer 

drought throughout the south−central and southeastern states, and an early winter snowstorm in the Southeast.2 

The estimated number of seasonal structure, vehicle, and outdoor fires are shown in Figure 1.3,4 Outdoor fires 

predominate in the spring and summer, structure fires peak in the winter, and vehicle fires are highest in the summer months and fairly constant the rest of the year. Nearly half of reported fires are outside fires, which accounts 

for much of the variation in the total number of fires throughout the year. Figures 2 and 3 present the daily incidence of total fires and of fires by property type, respectively. Figure 4 depicts the causes of fires by season. The 

following seasonal sections discuss the salient issues from these figures. 

S Federal Emergency Management Agency 

United States Fire Administration S National Fire Data Center 

Emmitsburg, Maryland 21727 

http://www.usfa.fema.gov/inside−usfa/nfdc/pubs/tfrs.shtm 

U.S. Department of Homeland Security 

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FIGURE 1. 2000 FIRE INCIDENTS BY SEASON


Outdoor 

Structure Vehicle and Other Total 

Winter 148,200 83,500 158,500 390,200 

Spring 125,500 86,200 255,100 466,800 

Summer 114,900 95,600 243,600 454,100 

Fall 116,800 83,200 196,800 396,800 

Total* 505,500 348,500 854,000 1,708,000 

*Estimates may not add due to rounding. 

Source: NFPA and NFIRS 

0 

2000 

4000 

6000 

8000 

10000 

NUMBER OF FIRES EACH DAY 

1/1

1/151/292/122/263/113/25

4/8

4/22

5/6

5/20

6/3

6/17

7/1

715

7/298/128/26

9/9

9/2310/7

10/21

11/4

11/18

12/2

12/1612/30 

FIGURE 2. 

Source: NFIRS 

0 

1250 

2500 

3750 

5000 

6250 

7500 1/1

1/151/292/122/263/113/25

4/8

4/22

5/6

5/20

6/3

6/17

7/1

715

7/298/128/26

9/9

9/2310/7

10/21

11/4

11/18

12/2

12/1612/30 

NUMBER OF FIRES BY PROPERTY TYPE EACH DAY 

Structure 

Vehicle 

All Outdoor 

FIGURE 3. 

Source: NFIRS 

2 
CAUSES OF FIRES BY SEASON (unknowns apportioned) 

0 5 10 15 20 25 30 

Incendiary/Suspicious 

Children Playing 

Smoking 

Heating 

Cooking 

Electrical Distribution 

Appliances 

Open Flame 

Other Heat 

Other Equipment 

Exposure 

Natural 

Percent 

Winter Spring Summer Fall

0 5 10 15 20 25 30 0 5 10 15 20 25 30 0 5 10 15 20 25 30 

Seasonal % Yearly Average % 

FIGURE 4. 

Source: NFIRS 

Winter has the lowest number of fires overall; however, heating and holiday fires create a unique profile of 

residential structure fires during this period. Heating is the leading cause of winter residential structure fires. On 

average, heating causes approximately 15% of residential structure fires throughout the year, but causes 25% of 

such incidents during the winter months.5 

Residential Heating Fires. Figure 5 clearly shows the daily incidence of heating fires increasing rapidly beginning in the cold weather months. (The large spike in early October was the result of multiple structure fires in 

Ohio and Texas.) Most homes have heating systems, but these systems range from fairly sophisticated new heating 

systems in the most modern homes to outdated gas, oil, or electrical heating equipment in many older homes and 

buildings. 

A heating fire is one that is caused by central heating units, fixed or portable room−size heating units, fireplaces, chimneys, water heaters, or other devices. Maintenance is a big issue, especially among single−family 

homes. Oil and gas heating systems in particular rely on a burning flame to create heat. These systems must be 

cleaned periodically and well maintained. 

FIGURE 5. NUMBER OF RESIDENTIAL STRUCTURE 

HEATING FIRES EACH DAY 

400 

350 

300 

250 

200 

150 

100 

50 

0 1/1

1/151/292/122/263/113/25

4/8

4/22

5/6

5/20

6/3

6/17

7/1

715

7/298/128/26

9/9

9/2310/7

10/21

11/4

11/18

12/2

12/1612/30 

Source: NFIRS 

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Most heating fires are initiated by space heaters (e.g., portable electric heaters, portable kerosene heaters, 

wood stoves, fireplaces with inserts, room gas heaters). 

Residential heating fires have dramatically declined since their peak in the early 1980s, when high energy 

prices sparked a trend toward alternative heating sources. Yet even though the use of wood-burning stoves and 

other alternative heating sources has declined, the risk of loss from heating fires is still high. The types of heating 

equipment vary by region. Equipment involved in heating fires in the South is likely to be chimneys, or perhaps 

cooking ovens in poorer households. In the North, heating fires are more often caused by central or space heating 

systems. Weather conditions account for the differences—central heating systems are less prevalent in southern 

homes than those in northern climes. 

Holiday Fires. Cultural and religious practices greatly increase the fire risk between December 1st and January 

7th each year (Figure 2). Christmas trees, candles, and easily ignited decorations commonly enjoyed in homes 

during the winter holidays represent a fire danger not present at other times of the year. The number of Christmas 

tree fires increases as the holiday season progresses because as trees and other greenery dry out they become more 

combustible. 

Cooking presents a fire risk in residential structures over the winter holidays, with notable spikes on Christmas 

and New Year’s days, and an equally notable dropoff on the day after each holiday. Children playing fires also 

spike during the holiday season, most notably around New Year’s Eve and New Year’s Day. 

Outdoor fires occur with increased frequency during the holidays. Open flame fires, those started by matches, 

embers, or campfires, lead the causes of outdoor winter fires. Although difficult to discern in Figure 3, there is a 

spike in outdoor fires around New Year’s Day due to fireworks and matches. 

SPRING FIRES 

The longer days and warming temperatures of spring are responsible for the highest incidence of fire among 

the four seasons. This elevated fire risk is largely tied to a substantial increase in outdoor fires, which includes 

grass, tree, and brush fires (Figure 6). High winds and low relative humidity in the spring warm the ground and 

dry out fallen leaves and other fuels. Lightning also begins to present a problem in the spring. Once started, stronger winds can fan an outside fire.6 Not all of these fires are due to natural causes. Warm weather brings people 

outside, and some of their activities—campfires, rubbish fires, outdoor grill fires—contribute to accidental fires. 

0 

1250 

2500 

3750 

5000 

6250 

7500 1/1

1/151/292/122/263/113/25

4/8

4/22

5/6

5/20

6/3

6/17

7/1

715

7/298/128/26

9/9

9/2310/7

10/21

11/4

11/18

12/2

12/1612/30 

All Outdoor 

Grass, Tree, Brush 

FIGURE 6. NUMBER OF NATURAL AND ALL OUTSIDE FIRES EACH DAY

Source: NFIRS 

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SUMMER FIRES 

Figure 4 shows that children playing, incendiary, smoking, other heat, and natural fires are at their highest in 

the summer. A large spike in summer fires occurs around the 4th of July. Natural fires due to lightning strikes are 

at their highest in the summer months, and the increasing use of gas and electric grills contribute to the summer 

fire problem. 

Fireworks sold for July 4th celebrations pose one of summer’s greatest fire risks. State laws regulating the sale 

of fireworks have a direct impact on the incidence of loss. A large number of states have imposed stringent laws 

on the sale and use of fireworks or have outlawed them altogether. As a result, fireworks injuries have decreased 

from a high of 12,100 in 1990 to a low of 8,500 in 1999; in 2000, there were 11,000 fireworks injuries.7 The 

most common ignition factor for fires related to fireworks is children playing with or otherwise misusing fireworks. Injuries are far more prevalent in jurisdictions that permit some type of fireworks sales than in jurisdictions 

where they are illegal. 

Most lightning strikes in the United States occur from June through August, igniting trees, brush, grass, or 

other outside materials. In 2000, several large forest fires in western states were caused by summer lightning 

strikes.8 Lightning is also responsible for a very high number of structure fires in the summer. 

Overall, grill fires have increased. Charcoal grill fires have decreased as the popularity of gas and electric grills 

has soared. Gas grills (liquid propane and natural gas) have a higher percentage of mechanical failures/malfunctions that result in fires than charcoal grills. 

FALL FIRES 

Fire incidence is at one of its lowest levels in the fall months. Outdoor fires begin to decline due to temperate 

weather, increased precipitation, and the waning of outdoor activities. Cooking fires are the only cause that is 

higher in the fall than the other seasons. The incidence of fall cooking fires peaks on Thanksgiving Day. The leading reason for the ignition of cooking fires is food left unattended on the stove or in the oven. 

CONCLUSION 

Armed with an understanding of the nature and scope of seasonal fires, the fire service has the opportunity to 

plan and implement specific public education, fire prevention, and other fire−related programs that address seasonal changes in fire incidence. Communities are encouraged to analyze their own seasonal and holiday fire incidence to determine how prevention initiatives and programs could best be targeted. It appears that much of the 

seasonality of fires is due to common behaviors and causes that are repeated each year. These repetitive causes and 

behaviors are candidates for clearly targeted prevention initiatives and programs. Locally as well as nationally, these 

initiatives and programs could have a major impact on the reduction of fire incidence. 

To request additional information, comment on this report, or review the detailed 

methodology used in this analysis, visit http://www.usfa.fema.gov/feedback/ . 

Notes: 

1.	 Estimates of the U.S. fire problem are taken from the National Fire Protection Association’s (NFPA’s) annual survey, Fire Loss in the 

United States. 

2.	 National Oceanic and Atmospheric Administration. http://www.ncdc.noaa.gov. 

3.	 National estimates are based on data from the National Fire Incident Reporting System (NFIRS) and the NFPA’s annual survey. At 

the time of this report, NFIRS was in the process of transitioning from version 4.1 to 5.0. Approximately 79% of the fire incident data for 2000 was reported to the USFA in NFIRS 4.1 format and converted to 5.0. 

4.	 Structure fire statistics and discussion in this report include mobile properties used as structures. 

5.	 Distribution statistics are based on data from NFIRS. 

6.	 Virginia Department of Forestry. http://www.vdof.org/fire/danger−rating.shtml. 

7.	 Consumer Product Safety Commission 2000 Fireworks Annual Report. 

8.	 USDA Forest Service. http://www.fs.fed.us/pnw/pubs/journals/ferguson_light2000.pdf. 

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