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Please Note: The data presented in this report are preliminary. Ranks and anomalies may change as more complete data are received and processed. Effective with the July 2009 State of the Climate Report, NCDC transitioned to the new version (version 3b) of the extended reconstructed sea surface temperature (ERSST) dataset. ERSST.v3b is an improved extended SST reconstruction over version 2. For more information about the differences between ERSST.v3b and ERSST.v2 and to access the most current data, please visit NCDC's Global Surface Temperature Anomalies page.
Temperature anomalies for October 2009 are shown on the dot maps below. The dot map on the left provides a spatial representation of anomalies calculated from the Global Historical Climatology Network (GHCN) dataset of land surface stations using a 1961-1990 base period. The dot map on the right is a product of a merged land surface and sea surface temperature (SST) anomaly analysis developed by Smith et al. (2008). For the merged land surface and SST analysis, temperature anomalies with respect to the 1971-2000 average for land and ocean are analyzed separately and then merged to form the global analysis. For more information, please visit NCDC's Global Surface Temperature Anomalies page.
Please Note: This preliminary assessment was made before data from Canada was made available. Therefore, some of the ranks presented in this report could change slightly when Canadian data is included in the final record. The inclusion of the missing data may cause modest changes to global-scale ranks. The assessment for Northern Hemisphere land temperatures could change by several ranks.
The combined global land and ocean surface temperature anomaly for October 2009 was 0.57°C (1.03°F) above the 20th century average, resulting in the sixth warmest October on record since records began in 1880. Similar to the combined global land and ocean temperatures, the worldwide land surface temperature was the sixth warmest October on record, with a temperature anomaly of 0.82°C (1.48°F) above the 20th century average. As shown in the dot maps above, warmer-than-average temperatures during the month of October were present across much of the world's land areas. The warmest anomalies occurred in the high latitudes of the Northern Hemisphere, specifically, in Alaska and northern and eastern Russia. Cooler-than-average conditions were present across the contiguous U.S., Scandinavia, New Zealand, and parts of northern Europe, northern Australia, and southern South America.
For the contiguous U.S., the national temperature average during October 2009 was much-below average, ranking in the top five coolest such month. Temperatures were below normal in eight of the nation's nine climate regions, with five of them much-below average. Please see the United States October 2009 National Overview for additional information.
According to New Zealand's National Institute of Water and Atmospheric Research (NIWA), New Zealand experienced anomalously cool conditions during October 2009, resulting in the coolest October since 1945. The national average was 10.6°C (51.1°F), 1.4°C (2.5°F) below the long-term October average. Many locations reported record low October temperatures, with temperatures over 2.0°C (3.6°F) below average.
In contrast, Darwin, Northern Territory, Australia experienced warmer-than-average temperatures during October 2009. The capital city recorded an average maximum temperature of 34.8°C (94.6°F) on October 2009, the highest on record for any month (Source: Australia's Bureau of Meteorology).
The worldwide sea surface temperatures (SST) during October 2009 were warmer than average across all oceans, with the exception of cooler-than-average conditions across much of the near-Antarctic southern oceans, the Gulf of Alaska, and parts of northwestern Atlantic Ocean, and along the western coasts of Australia and South America. The global ocean temperature represented the fifth warmest October on record, with an anomaly of 0.50°C (0.90°F) above the 20th century average. El Niño persisted across the equatorial Pacific Ocean during October 2009. Sea surface temperature anomalies were at least 1.0°C (1.8°F) above average across much of the central and east-central equatorial Pacific Ocean. El Niño is expected to strengthen and last through the Northern Hemisphere winter 2009-2010, according to NOAA's Climate Prediction Center (CPC).
The January-October 2009 map of temperature anomalies shows the presence of warmer-than-average conditions across much of the globe's surface, with the exception of cooler-than-average conditions across parts of Canada, the northern contiguous United States, the southern oceans, and along the northeastern Pacific Ocean. The combined global land and ocean surface temperature for the year-to-date period tied with 2007 as the fifth warmest January-October period on record. This value is 0.56°C (1.01°F) above the 20th century average.
The average position of the upper-level ridges of high pressure and troughs of low pressure (depicted by positive and negative 500-millibar height anomalies on the October 2009 map, respectively) are generally reflected by areas of positive and negative temperature anomalies at the surface, respectively. For other Global products, please see the Climate Monitoring Global Products page.
Images of sea surface temperature conditions are available for all weeks during 2009 from the weekly SST page.
| October | Anomaly | Rank (out of 130 years) |
Warmest Year on Record |
|---|---|---|---|
| Global | |||
| Land | +0.82°C (+1.48°F) | 6th warmest | 2005 (+1.07°C/1.93°F) |
| Ocean | +0.50°C (+0.90°F) | 5th warmest | 2003 (+0.58°C/1.04°F) |
| Land and Ocean | +0.57°C (+1.03°F) | 6th warmest | 2003 (+0.71°C/1.28°F) |
| Northern Hemisphere | |||
| Land | +0.83°C (+1.49°F) | 6th warmest | 2003 (+1.20°C/2.16°F) |
| Ocean | +0.53°C (+0.95°F) | 6th warmest | 2006 (+0.65°C/1.17°F) |
| Land and Ocean | +0.64°C (+1.15°F) | 5th warmest | 2003 (+0.85°C/1.53°F) |
| Southern Hemisphere | |||
| Land | +0.78°C (+1.40°F) | 6th warmest | 2002 (+1.09°C/1.96°F) |
| Ocean | +0.49°C (+0.88°F) | 3rd warmest | 1997 (+0.59°C/1.06°F) |
| Land and Ocean | +0.53°C (+0.95°F) | 5th warmest | 1997 (+0.61°C/1.10°F) |
| January - October | Anomaly | Rank (out of 130 years) |
Warmest Year on Record |
|---|---|---|---|
| Global | |||
| Land | +0.80°C (+1.44°F) | 5th warmest | 2007 (+0.99°C/1.78°F) |
| Ocean | +0.47°C (+0.85°F) | 6th warmest | 1998 (+0.53°C/0.95°F) |
| Land and Ocean | +0.56°C (+1.01°F) | 5th warmest | 1998 (+0.63°C/1.13°F) |
| Northern Hemisphere | |||
| Land | +0.84°C (+1.51°F) | 6th warmest | 2007 (+1.15°C/2.07°F) |
| Ocean | +0.47°C (+0.85°F) | 5th warmest | 2005 (+0.55°C/0.99°F) |
| Land and Ocean | +0.61°C (+1.10°F) | 5th warmest | 2007 (+0.71°C/1.28°F) |
| Southern Hemisphere | |||
| Land | +0.70°C (+1.26°F) | 3rd warmest | 2005 (+0.83°C/1.49°F) |
| Ocean | +0.49°C (+0.88°F) | 4th warmest | 1998 (+0.56°C/1.01°F) |
| Land and Ocean | +0.51°C (+0.92°F) | 5th warmest | 1998 (+0.60°C/1.08°F) |
The most current data may be accessed via the Global Surface Temperature Anomalies page.
The maps below represent anomaly values based on the GHCN dataset of land surface stations using a base period of 1961-1990. The areas with the wettest anomalies during October 2009 included the contiguous U.S., Brazil, the Philippine Islands, the southern Pacific islands, and parts of eastern Europe. The driest anomalies during October 2009 were observed across Alaska's panhandle and southern India.
Hurricane Rick, the 18th named storm for the eastern North Pacific basin in 2009, became the second-most intense North East Pacific hurricane on record, behind Linda of 1997, and the strongest hurricane to form in October since reliable records began. Rick made landfall near Mazaltan, Mexico on October 21st, producing heavy rain and causing two fatalities.
The Philippine Islands had well-above-average precipitation during October 2009. This was mainly due to the combined effects of Parma, Lupit, and Mirinae, which brought torrential rain across the islands, triggering fatal floods and wreaking havoc across the area.
Other notable precipitation extremes during October 2009 included heavy rain in Sicily, Italy. Over 200 mm (8 inches) of rain fell in a three-hour period on October 2nd. The heavy downpours triggered mudslides that claimed the lives of 20 people with 40 others missing. These were Italy's worst mudslides in over a decade. India's southern states—Karnataka and Andhra Pradesh—had their heaviest rainfall in over six decades. The effects of the copious rainfall were responsible for the deaths of 286 people and for leaving 2.5 million people homeless.
Additional details on flooding and drought can also be found on the October 2009 Global Hazards page.
As shown in the time series to the right, the average Northern Hemisphere October snow cover extent during October 2009 was above average. The Northern Hemisphere had the sixth largest snow cover extent on record. The average Northern Hemisphere October snow cover extent for the 1967-2009 period of record is 17.9 million square kilometers.
Across North America, snow cover for October 2009 was above average, the third largest extent since satellite records began in 1967. The average North American October snow cover extent is 8.1 million square kilometers for the 1967-2009 period of record. Significant winter storms brought heavy snow across parts of the United States. The U.S. saw a total of 931 new daily snowfall records, 68 new monthly snowfall records, and three all-time snowfall records, based on station data, during October 2009. For more information on the U.S. October 2009 snow events, please visit the U.S. 2009-2010 Snow Season Summary page.
As depicted in the time series to the right, Eurasia's snow cover extent during October 2009 was above average. This was the tenth largest snow cover extent on record. The average Eurasian snow cover extent in October is 9.9 million square kilometers for the 1967-2009 period of record.
Data were provided by the Global Snow Laboratory, Rutgers University.
According to the National Snow and Ice Data Center (NSIDC), the October 2009 Northern Hemisphere sea ice extent—which is measured from passive microwave instruments onboard NOAA satellites—was 7.5 million square kilometers (19.2 percent or 1.8 million square kilometers below the 1979–2000 average), resulting in the second least sea ice extent, behind 2007, since records began in 1979. This was mainly due to a period of slow ice growth at the beginning of October, contributing to the low October average sea ice extent. October Arctic sea ice extent has decreased at an average rate of 5.9 percent per decade since 1979.
Conversely, the October 2009 Southern Hemisphere sea ice extent was 1.6 percent above the 1979–2000 average. This was the ninth largest sea ice extent in October. Southern Hemisphere sea ice extent for October has increased at an average rate of 0.8 percent per decade.
For further information on the Northern and Southern Hemisphere snow and ice conditions, please visit the NSIDC News page, provided by NOAA's National Snow and Ice Data Center (NSIDC).
Temperatures above the Earth's surface are measured within the lower troposphere, middle troposphere, and stratosphere using in-situ balloon-borne instruments (radiosondes) and polar-orbiting satellites (NOAA's TIROS-N). The radiosonde and satellite records have been adjusted to remove time-dependent biases (artificialities caused by changes in radiosonde instruments and measurement practices as well as changes in satellite instruments and orbital features through time). Global averages from radiosonde data are available from 1958 to present, while satellite measurements date back to 1979.
These temperatures are for the lowest 8 km (5 miles) of the atmosphere. Information on the University of Alabama in Huntsville (UAH) and Remote Sensing Systems (RSS) sources of troposphere data is available.
| October | Anomaly | Rank (out of 31 years) |
Warmest Year on Record | Trend |
|---|---|---|---|---|
| UAH low-trop | +0.28°C/+0.50°F | 6th warmest | 2005 (+0.39°C/+0.70°F) | +0.14°C/decade |
| RSS low-trop | +0.28°C/+0.51°F | 7th warmest | 2003 (+0.46°C/+0.84°F) | +0.16°C/decade |
| January- October |
Anomaly | Rank (out of 31 years) |
Warmest Year on Record | Trend |
|---|---|---|---|---|
| UAH low-trop | +0.24°C/+0.43°F | 7th warmest | 1998 (+0.57°C/+1.03°F) | +0.12°C/decade |
| RSS low-trop | +0.25°C/+0.45°F | 8th warmest | 1998 (+0.61°C/+1.10°F) | +0.16°C/decade |
These temperatures are for the atmospheric layer centered in the mid-troposphere (approximately 3–10 km [2–6 miles] above the Earth's surface), which also includes a portion of the lower stratosphere. (The Microwave Sounding Unit [MSU] channel used to measure mid-tropospheric temperatures receives about 25 percent of its signal above 10 km [6 miles].) Because the stratosphere has cooled due to increasing greenhouse gases in the troposphere and losses of ozone in the stratosphere, the stratospheric contribution to the tropospheric average, as measured from satellites, may create an artificial component of cooling to the mid-troposphere temperatures. The University of Washington (UW) versions of the UAH and RSS analyses attempt to remove the stratospheric influence from the mid-troposphere measurements, and as a result the UW versions tend to have a larger warming trend than either the UAH or RSS versions. For additional information, please see NCDC's Microwave Sounding Unit page.
The radiosonde data used in this global analysis were developed using the Lanzante, Klein, Seidel (2003) ("LKS") bias-adjusted dataset and the First Difference Method (Free et al. 2004) (RATPAC). Additional details are available. Satellite data have been adjusted by the Global Hydrology and Climate Center at the University of Alabama in Huntsville (UAH). An independent analysis is also performed by Remote Sensing Systems (RSS) and a third analysis has been performed by Dr. Qiang Fu of the University of Washington (UW) (Fu et al. 2004) to remove the influence of the stratosphere on the mid-troposphere value. Global averages from radiosonde data are available from 1958 to present, while satellite measurements began in 1979.
Radiosonde measurements indicate that, for the January-October year-to-date period, temperatures in the mid-troposphere were 0.47°C (0.84°F) above average, resulting in the seventh warmest January-October (out of 52 years) since global radiosonde measurements began in 1958. Meanwhile, satellite analyses of the January-October year-to-date period for the middle troposphere varied from 7th to 12th warmest in the 31-year satellite record.
The global mid-troposphere temperatures were above average during October 2009. As shown in the table below, satellite measurements for October 2009 ranked fourth warmest to eighth warmest on record.
| October | Anomaly | Rank (out of 31 years) |
Warmest Year on Record | Trend |
|---|---|---|---|---|
| UAH mid-trop | +0.19°C/+0.34°F | 4th warmest | 1998 (+0.35°C/+0.63°F) | +0.07°C/decade |
| RSS mid-trop | +0.23°C/+0.41°F | 8th warmest | 1998 (+0.41°C/+0.75°F) | +0.11°C/decade |
| UW-UAH mid-trop | +0.26°C/+0.47°F | 6th warmest | 1998 (+0.51°C/+0.93°F) | +0.14°C/decade |
| UW-RSS mid-trop | +0.29°C/+0.53°F | 7th warmest | 1998 (+0.56°C/+1.02°F) | +0.18°C/decade |
| January- October |
Anomaly | Rank (out of 31 years) |
Warmest Year on Record | Trend |
|---|---|---|---|---|
| UAH mid-trop | +0.08°C/+0.14°F | 12th warmest | 1998 (+0.52°C/+0.94°F) | +0.04°C/decade |
| RSS mid-trop | +0.13°C/+0.23°F | 11th warmest | 1998 (+0.56°C/+1.01°F) | +0.09°C/decade |
| UW-UAH mid-trop | +0.18°C/+0.32°F | 7th warmest | 1998 (+0.66°C/+1.19°F) | +0.11°C/decade |
| UW-RSS mid-trop | +0.21°C/+0.38°F | 9th warmest | 1998 (+0.69°C/+1.24°F) | +0.15°C/decade |
| RATPAC* | +0.47°C/+0.84°F | 7th warmest | 1998 (+0.79°C/+1.43°F) | +0.15°C/decade |
*RATPAC's rank is based on records that began in 1958 (52 years).
The table below summarizes stratospheric conditions for October 2009. On average, the stratosphere is located approximately 16–23 km (10–14 miles) above the Earth's surface. Over the last decade, stratospheric temperatures have been below average in part due to the depletion of ozone. The large positive anomaly in 1982 was caused by the volcanic eruption of El Chichon in Mexico, and the sharp jump in temperature in 1991 was a result of the eruption of Mt. Pinatubo in the Philippines. In both cases the temperatures returned to pre-eruption levels within two years.
| October | Anomaly | Rank (out of 31 years) |
Coolest Year on Record |
|---|---|---|---|
| UAH stratosphere | -0.44°C (-0.79°F) | 14th coolest | 2000 (-0.81°C/-1.46°F) |
| RSS stratosphere | -0.50°C (-0.91°F) | 10th coolest | 2000 (-0.79°C/-1.42°F) |
For additional details on precipitation and temperatures in October, see the Global Hazards page.
Christy, John R., R.W. Spencer, and W.D. Braswell, 2000: MSU tropospheric Temperatures: Dataset Construction and Radiosonde Comparisons. J. of Atmos. and Oceanic Technology, 17, 1153-1170.
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