Monthly average temperatures were 1 to 3 °F above the 1991-2020 normal for much of Arizona (light-orange and orange areas on map), with several areas in the southern half of the state recording temperatures 3 to 5 °F above normal (dark-orange and light-red-orange areas on map). For reference, monthly average temperatures in April 2025 were within 2 °F of normal for almost all of the state.

Area-average maximum and minimum temperatures during April 2026 were 74.9 and 46.9 °F for the Sonoita AVA, 77.6 and 45.7 °F for the Verde Valley AVA, and 78.2 and 46.5 °F for the Willcox AVA. Respective April normals are 73.5 and 41.9 °F, 75.5 and 42.6 °F, and 76.7 and 42.0 °F.

Temperature last month ranged between 85.3 and 34.0 °F at the AZMet Bonita station, 82.0 and 37.8 °F at the AZMet Elgin station, and 85.3 and 36.0 °F at the AZMet Willcox Bench station.

Monthly precipitation totals were less than 25 % of normal for much of the southern half and along the western border of the state (dark-yellow areas on map). These areas quickly transition to those measuring near-normal amounts across much of the rest of Arizona (white areas on map). Precipitation during April 2025 was less than 50 % of normal for much of western and southern Arizona. These areas transitioned to one in north-central and northwestern parts of the state where amounts were greater than 125 % of normal.

Area-average precipitation totals in April 2026 were 0.03 inches for the Sonoita AVA, 0.38 inches for the Verde Valley AVA, and 0.03 inches for the Willcox AVA. Respective April normals are 0.38, 0.55, and 0.25 inches.

Total precipitation last month was 0.06, 0.15, and 0.24 inches at the AZMet Bonita, Elgin, and Willcox Bench stations, respectively.

Dig further into daily weather summaries for the AZMet Bonita and Willcox Bench stations in the Willcox AVA and the AZMet Elgin station in the Sonoita AVA.

Learn more about PRISM climate data.

Temperatures over the course of this month have a slight increase in chances for being above the 1991-2020 normal across all of Arizona (light-orange and orange areas on map area on map). Monthly average temperatures in May 2025 were near normal for much of the state.

Area-average maximum and minimum temperatures during May 2025 were 81.2 and 50.0 °F for the Sonoita AVA, 85.2 and 51.2 °F for the Verde Valley AVA, and 83.8 and 49.9 °F for the Willcox AVA. Respective May normals are 81.7 and 49.6 °F, 84.5 and 50.0 °F, and 84.8 and 48.9 °F.

Temperature in May last year ranged between 94.5 and 40.1 °F at the AZMet Bonita station and between 96.3 and 39.6 °F at the AZMet Willcox Bench station.

Precipitation totals for this month have a slight increase in chances for being above normal across the southeastern part of the state (light-aqua and aqua areas on map), mainly due to the likelihood of rain in early May. For the rest of Arizona, there are equal chances for below-, near-, or above-normal totals (white area on map). Precipitation during May 2025 was more than 250 % of normal for much of the west-central part of the state. In contrast, much of the southeastern part of the state saw totals less than 75 % of normal. Amounts were near normal for much of the northeastern corner of Arizona.

Area-average precipitation totals in May 2025 were 0.00 inches for the Sonoita AVA, 0.78 inches for the Verde Valley AVA, and 0.03 inches for the Willcox AVA. Respective May normals are 0.22, 0.44, and 0.29 inches.

Total precipitation in May last year was 0.00 and 0.00 inches at the AZMet Bonita and Willcox Bench stations, respectively.

To stay informed of long-range temperature and precipitation possibilities beyond the coverage of a standard weather forecast, check in, too, with the six-to-ten-day outlook and eight-to-fourteen-day outlook issued daily by NOAA’s Climate Prediction Center.

Heat accumulation during April this year at the AZMet Willcox Bench station in the south-central part of the Willcox AVA is greater than what it was last year (top two rows of table). This suggests that the growth rate of vines may have been faster and the time between pre-veraison growth stages shorter so far this growing season than what they were in the previous one. Heat accumulation this year is above average, as indicated by the positive percent value in the third table column, and the greatest it has been during April since station measurements began.

Relative to last year, how much more advanced might vine growth stages be this year due to the additional heat accumulation? As daily accumulation of growing degree hours during April is approximately 250 on average, and the difference in cumulative growing degrees hours between 2026 and 2025 is 2,016, the additional heat accumulation during April 2026 is worth about eight days. Coupling this with bud break dates in 2026 that we’ve heard were the earliest ever, growth stages might be about three weeks ahead of where they were last year, depending on variety.

Digging more into the bud break and flowering dates from Buhl Memorial Vineyard during the 2023 through 2025 growing seasons, the average amount of time between these two vine growth stages across varieties is about one month, with a range from 28.4 days (Cabernet Sauvignon) to 35.3 days (Sangiovese). Given this range, the flowering period there generally lasts about one week.

In terms of heat accumulation, an average of 8,805.6 growing degree hours occurs between these two vine growth stages across all varieties, with a range from 8,206.3 (Viognier) to 9,873.8 (Petite Sirah). These values are based on temperature data from the AZMet Willcox Bench station in the south-central part of the Willcox AVA.

A few points come to mind from these statistics and other ones shown in the table. Despite data from just a few growing seasons, variability in average duration and heat accumulation among the varieties may reflect their genetic variability. Also, given heat accumulation during April 2026 relative to that from the previous three years, one might expect the amount of time between bud break and flowering for all varieties this growing season to be less than the minimum duration observed during the 2023 through 2025 growing seasons. And finally, ranges of duration and heat accumulation for an individual variety may suggest that windy conditions are decoupling the developmental rate of vines from what is inferred from heat accumulation alone. Higher wind speeds increase evapotranspiration demand at a given temperature, potentially resulting in slower metabolism as vines lower stomatal conductance to reduce water vapor loss, which consequently decreases carbon dioxide uptake.