Climate of 2001
August in Historical Perspective

National Climatic Data Center, 17 September 2001

Global Highlights:

• Global average land and sea surface temperature was the second warmest on record for August and for the boreal summer (June-August)
• Lower tropospheric temperatures were warmer than average for August, but near average for June-August
• Temperatures in the lower stratosphere were cooler than average
• During June-August, above average precipitation was most notable across southeast China, Argentina and the U.S. Gulf Coast, with below average precipitation across the Mediterranean, northern India and northern South America

Contents of this Section:

• Introduction
• Global Temperatures
• Global Precipitation
• Microwave Sounding Unit Data

Introduction

Using a 1992-2001 base period as shown in the adjacent blended temperature product of satellite and in-situ data, anomalous warmth during the period June-August in the Northern Hemisphere was linked to the location of upper level ridges of high pressure. These ridges of high pressure (depicted by positive 500 millibar height anomalies) were situated across much of Canada and the western U.S., as well as eastern Europe and Siberian regions of the Former Soviet Union (FSU). Temperature anomalies calculated from in-situ station data using a 1961-1990 base period also show the warmer than average temperatures in these regions with cooler than average temperatures restricted to British Columbia, portions of India and the Kamchatka Peninsula. Similar temperature distributions were present during August.

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Temperature

Although neutral ENSO conditions were present in August, the global land and ocean temperature was second warmest in the 1880 to present record and was 0.58°C (1.04°F) above the long-term average (0.49°C / 0.88°F above the 1961-1990 mean) Temperatures averaged across land areas also ranked second warmest, or 0.90°C (1.62°F) above the long-term August mean

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For summer (June-August), the global average land and ocean temperature was 0.53°C (0.95°F) above the 1880-2000 mean, or second warmest (0.44°C / 0.79°F above the 1961-1990 mean) Northern and Southern Hemisphere temperatures were both second warmest during June-August, or 0.67°C (1.21°F) and 0.39°C (0.70°F) above average, respectively

Based on data available at the time of this report, the average temperature approached record levels for the period June-August across the Northern Hemisphere extratropics, with the combined land and ocean temperature falling less than 0.01°C (0.02°F) short of the record anomaly of 0.83°C (1.49°F) set during the El Niño summer of 1998

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Precipitation

Much above average precipitation over the U.S. Gulf Coast and Southeast Asia was largely due to tropical systems Precipitation departures during June-August were 100-200 mm (3.94-7.87 inches) across central Argentina Monsoon rains were lighter than average across much of northern and western India A persistent upper level trough of low pressure brought unusually wet weather to South Africa in August

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Microwave Sounding Unit Data

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Summer temperatures in the lowest 8km (5 miles) of the troposphere were near average Lower tropospheric temperatures in August were above average (0.16°C / 0.29°F)

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June-August temperature was below average in the lower stratosphere, with a departure of -0.29°C (-0.52°F) This was the 9th consecutive August with below average stratospheric temperatures (-0.27°C / -0.49°F)

For additional details on precipitation and temperatures in June see the Global Regional page .

References:

Peterson, T.C. and R.S. Vose, 1997: An Overview of the Global Historical Climatology Network Database. Bull. Amer. Meteorol. Soc., 78, 2837-2849.

For all climate questions other than questions concerning this report, please contact the National Climatic Data Center's Climate Services Division:

Climate Services Division
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fax: 828-271-4876
phone: 828-271-4800
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For questions about this report, please contact:

David Easterling
NOAA/National Climatic Data Center
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Asheville, NC 28801-5001
fax: 828-271-4328
email: David.Easterling@noaa.gov

Jay Lawrimore
NOAA/National Climatic Data Center
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Asheville, NC 28801-5001
fax: 828-271-4328
email: Jay.Lawrimore@noaa.gov

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