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Regional Climate Overview - August | September | October | CLIMAS

Regional Climate Overview - August | September | October

Regional Climate Overview - August | September | October

Temperatures over the past three months (August-October) were 1-3 °F (0.6-1.7 °C) above average for almost all of New Mexico and West and East Texas (Figure 1, left). Temperatures were 0-2 °F (0-1.1 °C) below average for Central Texas. Precipitation over the same time period was 50-90% of average for Central and Northwest New Mexico, 100-130% of average for the remaining areas of New Mexico, and 150-300% of average for most of Texas (Figure 1, right). Several heavy rain events in October led to extreme flooding. It was the wettest October on record for Texas, with 6.86 inches of precipitation, 4.33 inches above average. From January-October, New Mexico experienced record warm average and maximum temperatures (NOAA State of the Climate).

Figure 1 (above): Departure from average temperature in degrees F (left) and percent of average precipitation (right), compared to the 1981–2010 climate average, for 8/1/2018–10/31/2018. Maps from HPRCC.

Temperatures from November 1 through 14 were 0-8 °F (0-4.4 °C) below average for most of both New Mexico and Texas (figure not shown). Precipitation over the same time period was 0-25% of average for western and southern New Mexico, and parts of Central Texas, and 200-400% of average for East Texas.

Temperatures were colder than normal in most of Sonora and Sinaloa, in part due to convective activity in September and October, where temperatures were 3.6-5.4 °F (2 to 3 °C) below average. Another region with below-average temperatures was northern Coahuila, where anomalies were less than to 1.8 °F (1 °C). In the rest of northern Mexico, the warmest anomalies were concentrated in Chihuahua and Durango (5.4 °F, 3 °C), Zacatecas, San Luis Potosí and Tamaulipas, with anomalies less than 5.4 °F (3 °C) (Figure 2, left). Areas where there were more than 50 days with maximum temperatures above 104 °F (40 °C) were in Mexicali and San Luis Río Colorado (between Baja California-Sonora). In the rest of the country, the number of days above this threshold has started to decline, as the seasons change from summer to winter (Figure 2, right).

Figure 2 (above): Temperature anomalies in °C (left) and number of days with maximum temperatures at or above 104 °F (40 °C) (right) for August-October. Maps from SMN.

More than 31.4 inches (800 mm) of precipitation accumulated in Nayarit this quarter, thanks to the incursion of Hurricane Willa in October. Totals above 23.6 inches (600 mm) accumulated in southern Tamaulipas and eastern San Luis Potosí (Figure 3, left). The last three months brought very beneficial rains in the North, with most of Sonora, Chihuahua, Coahuila, Durango and Zacatecas experiencing above-average precipitation that has helped to lessen drought concerns. The only areas with below-average precipitation were northern Baja California, Central Baja California Sur, Tamaulipas, eastern San Luis Potosí, and northern Veracruz, in The Huastecas region (Figure 3, right).

Figure 3 (above): Accumulated precipitation in mm (left) and percent of normal (right) for August-October. Maps from SMN.


Drought conditions decreased in severity across the region over the past month, according to the North American Drought Monitor (NADM) (Figure 4). Drought has been almost eliminated from Texas, due to record-breaking precipitation in October. Extreme to exceptional drought still covers northern New Mexico, and abnormally dry to severe drought conditions cover the rest of the state.  Drought conditions are still not present in the northern Mexico states, with only small areas in Chihuahua and Tamaulipas experiencing abnormally dry to moderate drought conditions. Drought conditions are predicted to continue, but decrease in severity across northern New Mexico, by the end of February, according to the U.S. Seasonal Drought Outlook.

Figure 4 (above): North American Drought Monitor, released November 13, 2018.