7. Table of Contents
a. Overview
This chapter provides summaries of the 2023 temperature and precipitation conditions across seven broad regions: North America, Central America and the Caribbean, South America, Africa, Europe and the Middle East, Asia, and Oceania. In most cases, summaries of notable weather events are also included. Local scientists provided the annual summary for their respective regions and, unless otherwise noted, the source of the data used is typically the agency affiliated with the authors. The base period used for these analyses is 1991–2020, unless otherwise stated. Please note that on occasion different nations, even within the same section, may use unique periods to define their normal. Section introductions typically define the prevailing practices for that section, and exceptions will be noted within the text. In a similar way, many contributing authors use languages other than English as their primary professional language. To minimize additional loss of fidelity through re-interpretation after translation, editors have been conservative and careful to preserve the voice of the author. In some cases, this may result in abrupt transitions in style from section to section.
b. North America
—L. Stevens, Ed.
Above-average temperatures were observed across Canada, large portions of the contiguous United States, and the majority of Mexico in 2023, with record-high annual temperatures in many locations. All other regions were near or slightly below average. Averaged as a whole, North America’s annual temperature was 1.13°C above the 1991–2020 base period and was the warmest year in the 114-year continental record (extends back to 1910).
Precipitation varied across North America in 2023. All three countries experienced widespread drought events, with Mexico reporting its driest year on record (since 1950).
Several extreme events occurred during the year, including a record-breaking Canadian wildfire season (Sidebar 7.1). Other notable events included heavy rainfall and flooding in Nova Scotia (NS), heatwaves in both the United States and Mexico, and Hurricane Otis.
Information in this section relates to the geographic continent of North America. Regions of the United States outside the contiguous United States are described in other sections of the report: Alaska (Chapter 5), Puerto Rico (section 7c1), and Guam and the U.S.-Affiliated Pacific Islands (section 7h2). Limited temperature and precipitation data are available for Hawaii but will be included in future reports. Tropical cyclone events affecting all regions are described in Chapter 4.
Anomalies in this section are all with respect to the 1991–2020 base period, unless otherwise noted.
1. CANADA
—V. Y. S. Cheng, F. Wu, M. Beauchemin, and L. Chisholm
Overall, Canada had its second-warmest year on record. National average temperatures for summer and autumn of 2023 were the highest recorded in the nation’s 76-year record (1948–2023). National winter and spring temperatures were also above the 1991–2020 average. The temperature records presented in this section are based on adjusted and homogenized Canadian climate data.
(i) Temperature
The annual 2023 average temperature for Canada was 1.8°C above the 1991–2020 average and ranked as the second-warmest year on record, behind only 2010 (Fig. 7.1). Over the past 76 years (1948–2023), the national annual average temperature exhibited a warming of 2.0°C, with 3 of the 10 warmest years occurring since 2015. Spatially, annual anomalies of more than +1.0°C were recorded across most of Canada in 2023, with annual anomalies of more than +2.5°C recorded in most of the Northwest Territories and the western part of Nunavut (Fig. 7.2). Four of the 13 provinces and territories (British Columbia, Alberta, the Yukon, and the Northwest Territories) experienced their highest annual temperatures on record.
Annual average temperature anomalies (°C; 1991–2020 base period) in Canada for the period 1948–2023. The black line represents an 11-year running mean. (Source: Environment and Climate Change Canada.)
Citation: Bulletin of the American Meteorological Society 105, 8; 10.1175/2024BAMSStateoftheClimate_Chapter7.1
Annual average temperature anomalies (°C; 1991–2020 base period) in Canada for 2023. (Source: Environment and Climate Change Canada.)
Citation: Bulletin of the American Meteorological Society 105, 8; 10.1175/2024BAMSStateoftheClimate_Chapter7.1
Seasonally, the national average temperature for winter (December 2022–February 2023) was 0.3°C above the 1991–2020 average, making it the 19th warmest on record. The highest winter anomalies of +2.5°C were recorded in eastern Ontario and western Quebec.
During spring (March–May), temperature anomalies of at least +0.5°C were observed in most of northern and eastern Canada, while temperature anomalies of at least −0.5°C were observed in the western Yukon, southern Saskatchewan, and Manitoba and western Ontario. The national average temperature for spring 2023 was 1.1°C above average, making it the seventh-warmest spring on record.
The national average temperature for summer (June–August) was 1.2°C above average, the highest on record. Summer anomalies of more than +2.5°C were recorded in the northern region of the Yukon and the Northwest Territories. British Columbia, the Yukon, and the Northwest Territories each had their highest summer temperatures on record.
The national average temperature for autumn (September–November) was 2.4°C above average, making it the warmest autumn on record. Most of the Northwest Territories and Nunavut experienced temperatures 3.0°C or more above average. The Northwest Territories observed their highest autumn temperatures on record, with Nunavut, Quebec, and Alberta each having their second-highest temperatures on record. All provinces and territories had average temperatures among their 10 highest on record for autumn 2023.
(ii) Precipitation
With the evolution of precipitation monitoring technology, Environment and Climate Change Canada (ECCC) and its partners implemented a transition from manual observations to the use of automatic precipitation gauges. Extensive data integration is required to link the current precipitation observations to the long-term historical manual observations. The update and reporting of historical adjusted precipitation trends and variations has been on temporary hiatus pending an extensive data reconciliation, and will be resumed thereafter. ECCC remains committed to providing credible climate data to inform adaptation decision making, while ensuring that the necessary data reconciliation occurs as monitoring technology evolves.
(iii) Notable events and impacts
Canada experienced yet more extremes in 2023. Several heatwaves occurred, and nationwide wildfires set records. A subtropical storm affected the Atlantic Northeast in January, and Hurricane Lee made landfall as a post-tropical cyclone in NS in September. Meanwhile, drought conditions lingered across the country (see the North American Drought Monitor for monthly maps of drought conditions [National Drought Mitigation Center 2024]).
Most notable was the unprecedented wildfire activity across the country (see Sidebar 7.1 for more information). The second most notable was the heavy rainfall in NS that took place on 21–22 July, where a slow-moving trough of low pressure interacted with moist flow from the tropics. Widespread rainfall with totals ranging from 50 mm to 150 mm was observed across NS and eastern Prince Edward Island (Fig. 7.3); locally heavier precipitation of 200 mm to 260 mm fell in parts of Halifax, NS. This event resulted in more than twice the monthly average total rainfall for July (75 mm to 110 mm) in just over two days in the hardest hit areas—the most rain to affect the region in 50 years. Bedford Range, NS, just northwest of Halifax, broke the national rainfall rates record (based on ECCC stations) with 173.4 mm falling over six hours, well exceeding a 1-in-100-year event.
Total precipitation accumulation (mm) during 21–22 July 2023 over Nova Scotia and eastern Prince Edward Island. Darkest blue indicates over 225 mm of rain. (Source: National Laboratory, Meteorological Service of Canada, Environment and Climate Change Canada [ECCC].)
Citation: Bulletin of the American Meteorological Society 105, 8; 10.1175/2024BAMSStateoftheClimate_Chapter7.1
The compounding effect (Singh et al. 2023) of abnormally wet antecedent conditions made this torrential rainfall event even more impactful. Rain had been falling over the region for much of the previous six weeks leading up to the July storm. The already saturated ground led to catastrophic flooding, which damaged infrastructure and led to the loss of four lives when their vehicles were caught in flood waters.
A province-wide state of emergency was declared in NS, with some areas receiving evacuation orders that displaced about 1000 residents (ECCC 2024). Numerous roads and highways were impassable. More than 80,000 homes and businesses lost power. Agricultural losses were also extensive owing to flooded fields, where crops were left submerged for several days (ECCC 2024). In total, this event caused over $236 million Canadian dollars ($179 million U.S. dollars) in insured damage according to the CatIQ database (CatIQ 2024).
2. UNITED STATES
—K. Gleason, C. Fenimore, R. R. Heim Jr., and A. Smith
The annual average temperature for the contiguous United States (CONUS) in 2023 was 12.5°C, which was 0.6°C above the 1991–2020 average, making 2023 the fifth-warmest year in the 129-year record (Fig. 7.4a). Above-average to record-high temperatures were concentrated from the Plains to the East Coast and across portions of the Northwest, while near-average temperatures were observed from California to the central Rockies (Fig. 7.5a). Based on a linear regression of data from 1895 to 2023, the annual CONUS temperature is increasing at an average rate of 0.09°C decade−1 (0.27°C decade−1 since 1970). Average annual precipitation for the nation totaled 749 mm, which is 94% of the 1991–2020 average (Fig. 7.4b). Overall, the annual precipitation total has been increasing at an average rate of 4 mm decade−1 since 1895 (1 mm decade−1 since 1970). The average annual temperature across Alaska in 2023 was 0.2°C above average and 17th highest in the 99-year record. Precipitation was 116 mm above average and fifth wettest on record. The annual temperature for Alaska has been increasing at an average rate of 0.17°C decade−1 since 1925 (0.44°C decade−1 since 1970). Precipitation is increasing at an average rate of 2 mm decade−1 since 1925 (21 mm decade−1 since 1970).
Annual (a) mean temperature anomalies (°C) and (b) precipitation anomalies (mm; 1991–2020 base period) for the contiguous United States during the period 1895–2023. The black lines represent a 10-year running mean. (Source: NOAA/NCEI.)
Citation: Bulletin of the American Meteorological Society 105, 8; 10.1175/2024BAMSStateoftheClimate_Chapter7.1
Annual (a) average temperature anomalies (°C) and (b) total precipitation (% of average) in the contiguous United States for 2023 (1991–2020 base period). (Source: NOAA/NCEI.)
Citation: Bulletin of the American Meteorological Society 105, 8; 10.1175/2024BAMSStateoftheClimate_Chapter7.1
(i) Temperature
The winter (December 2022–February 2023) CONUS temperature was 0.5°C above average, with anomalous warmth stretching from the southern Plains to the Great Lakes and East Coast. Conversely, the CONUS spring (March–May) temperature was 0.4°C below average with below-average temperatures extending from the West Coast to the northern Plains and above-average temperatures east of a line from southern New Mexico to the Great Lakes. The summer (June–August) CONUS temperature was 0.4°C above average with record warmth along parts of the Gulf Coast. Louisiana had its warmest summer on record while Texas was second warmest. The autumn (September–November) CONUS temperature was 0.9°C above average, the sixth highest on record. Most of the CONUS experienced above-average temperatures with record heat observed across portions of New Mexico and Texas.
(ii) Precipitation
The climate of the CONUS in 2023 was driven by a broad ridge of high pressure over the central United States, particularly during the second half of the year, which was coincident with a rapid shift from La Niña conditions that lasted for three winters to a strong El Niño by October of 2023 (see section 4). Louisiana had its ninth-driest year on record while Maine observed its fifth wettest (Fig. 7.5b).
Winter precipitation across the CONUS was 110% of average and ranked in the wettest third of the historical record. Precipitation was above average from California to the Great Lakes and across portions of the Mississippi River Valley and the Northeast. Precipitation totals for Minnesota and Iowa were both third highest on record, and for Wisconsin were the second highest for this winter season. Spring precipitation was near-average (95% of average) for the CONUS, but was below average across portions of the central Plains, Midwest, and Mid-Atlantic. Both Pennsylvania and Maryland had their ninth-driest spring on record. Summer precipitation across the CONUS was 97% of average. Conditions were dry from the Southwest to the central Gulf Coast and in portions of the Northwest and Upper Midwest. Above-average rainfall impacted parts of the West, Plains, and much of the Northeast. Wyoming, Maine, New Hampshire, and Vermont each had their wettest summer on record, while New Mexico and Louisiana both observed their third driest. The autumn CONUS precipitation total was 15th lowest on record at 77% of average. Precipitation was below average across portions of the West, central Plains, and a large portion of the Midwest, Tennessee, and Lower Mississippi River valleys. Tennessee had its third-driest autumn on record.
Drought coverage across the CONUS remained significant for the fourth consecutive year, beginning with maximum coverage for the year of 46% on 3 January when the most intense areas of drought spanned parts of the West as well as the central and southern Plains. The drought area contracted over the first half of the year, reaching a minimum extent of 19% on 30 May, as drought waned across the West, Midwest, Plains, and Southeast. It expanded throughout the summer and early autumn, reaching a secondary peak of 40% on 3 October, with the epicenter expanding from the central Plains to the Upper Midwest, Deep South, and Pacific Northwest. Warm temperatures and dry conditions led to a flash drought that emerged across portions of the Gulf Coast states and Southeast, with parts of the Mississippi River reaching record-low levels in October. By the end of 2023, the drought area contracted to 33% of the CONUS, impacting portions of the Southeast, Plains, and Lower Mississippi River Valley. In Hawaii, the lower elevations of Maui saw an expansion of severe drought in early August. These dry conditions, combined with strong, dry winds instigated b