Climatological Background

In July, heating of the continents in the northern hemisphere results in strengthened monsoon systems which bring rains to West Africa, South Asia, and southwestern North America. In the southern hemisphere, winter has set in, with stronger north-south temperature gradients fueling active mid-latitude storm tracks.

Monthly Mean Temperature (1961-1990), data from the Climate Research Unit, University of East Anglia

Monthly Mean Precipitation (1961-1990), data from the Climate Research Unit, University of East Anglia

Temperatures

Above-average temperatures continued to dominate over much of the northern hemisphere. Record and near-record July temperatures were recorded in Western Europe and much of the United States. Lower-than-average temperatures to the east of the Urals provided the only major change in the previous month’s temperature pattern (Temperature Persistence Map). Above-average temperatures dominated the tropics and sub-tropics as well as most of the southern hemisphere. An exception, however, was northern Australia which has experienced below-average temperatures since May.

Temperature Difference from the 1961-1990 mean, with data from NCEP Climate Prediction Center, CAMS.

Precipitation

Precipitation Difference from 1979-2000 mean, with data from NCEP Climate Prediction Center, CAMS-OPI.

Oceanic Conditions

A small area of positive sea surface temperature (SST) anomalies was observed near the dateline in the equatorial Pacific. Otherwise, SSTs during July were near average across most equatorial regions. In the Atlantic, the relatively small areal extent and magnitude of the July SST anomalies were in stark contrast to the large positive SST anomalies observed in June. In the mid and high latitudes of the northern hemisphere, SST anomaly patterns were very similar to those observed in June.

Monthly Sea Surface Temperature Difference from the 1971-2000 mean, with data from the Environmental Modeling Center, NCEP/NOAA.