Southwest Climate Outlook October 2020

Date issued

Monthly Precipitation and Temperature: September precipitation ranged between record driest and below average in most of Arizona and much of New Mexico (Fig. 1a). September temperatures were above average to record warmest in Arizona and average to above average in most of New Mexico (Fig. 1b). The daily average temperature anomalies for Sept. 1 – Oct. 14 (Fig. 2) highlight the fluctuations at select stations around the region.

Monsoon Precipitation: Monsoon precipitation (June-July-August-September) was record driest to much below normal (bottom 10%) across Arizona and ranged from near normal to record driest in most of New Mexico (Fig. 3) (See Monsoon Recap).

Water Supply: Water year precipitation (Oct 2019 – Sept 2020) was near normal to above normal in parts of southwestern Arizona and southern New Mexico (along with west Texas and southern California), while most of the Four Corners region, northern New Mexico, and southern Colorado were below normal or much below normal (Fig. 4). Many of the reservoirs in the region are at or below the values recorded at this time last year. Most are below their long-term average (see Arizona and New Mexico reservoir storage).

Drought: The Sept. 4 U.S. Drought Monitor (USDM) showed widespread areas of extreme drought (D3) and pockets of exceptional drought (D4) across Arizona and New Mexico, along with much of Nevada, Utah, and Colorado (Fig. 5). A major driver for this drought characterization was the well below average monsoon precipitation and accumulated long term precipitation deficits. The USDM from Jun. 30, 2020, highlights just how much drought expanded with the record or near-record dry monsoon across much of the southwest (Fig. 6)

ENSO Tracker: La Niña conditions are present and are expected to continue through winter (see ENSO-tracker for details).

Precipitation and Temperature Forecast: The three-month outlook for Nov through Jan calls for increased chances for below-normal precipitation across much of the southwestern U.S. and all of northern Mexico (Fig. 7, top). The three-month temperature outlook calls for increased chances of above-normal temperatures across most of the southwestern U.S. and northern Mexico (Fig. 7, bottom).

Published by the Climate Assessment for the Southwest (CLIMAS), with support from University of Arizona Cooperative Extension, the Arizona State Climate Office, and the New Mexico State Climate office.

Disclaimer. This packet contains official and non-official forecasts, as well as other information. While we make every effort to verify this information, please understand that we do not warrant the accuracy of any of these materials. The user assumes the entire risk related to the use of this data. CLIMAS, UA Cooperative Extension, and the State Climate Office at Arizona State University (ASU) disclaim any and all warranties, whether expressed or implied, including (without limitation) any implied warranties of merchantability or fitness for a particular purpose. In no event will CLIMAS, UA Cooperative Extension, and the State Climate Office at ASU or The University of Arizona be liable to you or to any third party for any direct, indirect, incidental, consequential, special or exemplary damages or lost profit resulting from any use or misuse of this data.