Highest temperature in Phoenix on Apr 12, 2026?

Long-range climate models consistently predict a high chance of La Niña. Major climate centers forecast a strong probability of La Niña conditions persisting through Spring (March-April-May) 2026. The Climate Prediction Center (CPC)/IRI projects an 80% chance of La Niña, with lower probabilities for ENSO-neutral (15%) or El Niño (5%) ^[1]. Similarly, the ECMWF's SEAS5 model indicates a 75% probability of continued La Niña, noting increased confidence following a strong El Niño event ^[4]. This outlook is further supported by the IRI's March 2026 Quick Look and the World Meteorological Organization (WMO) update from February 2026, both forecasting a 70-85% chance of La Niña extending through Spring 2026 ^[5].

Phoenix April temperatures historically vary by ENSO phase. Over the past 40 years, Phoenix, Arizona, has experienced an average April temperature of approximately 75.0°F (23.9°C) ^[2]. During La Niña events, April temperatures in Phoenix tend to be warmer than average, typically showing anomalies ranging from 2 to 5°F (1.1 to 2.8°C) above the historical mean ^[3]. In contrast, El Niño events usually result in April temperatures close to or slightly below normal, with anomalies generally within +/- 1°F (0.6°C) of the long-term average ^[6]. ENSO-neutral conditions typically lead to near-average temperatures, with anomalies seldom exceeding +/- 1.5°F (0.8°C) ^[6].

The localized Urban Heat Island effect significantly increased Phoenix Airport temperatures since 1990. Between 1990 and 2004, the localized Urban Heat Island (UHI) effect at the Phoenix Sky Harbor Airport (KPHX) measurement site contributed approximately 0.9°F per decade to the daily maximum temperature trend when compared to surrounding undeveloped areas ^[1]. While specific data for mid-April is not provided, this trend highlights the overall influence of urban development on maximum daily temperatures in the region during this timeframe.

Urbanization consistently elevated maximum temperatures across the Phoenix metropolitan area. Further research supports the general impact of the UHI effect on warming trends in Phoenix across various periods. For instance, between 1970 and 2000, the UHI intensity for daytime maximum temperatures increased by roughly 1.08°F per decade ^[2]. Additionally, from 1950 to 2010, the UHI effect added about 0.2°F per decade to maximum temperatures at urban stations compared to rural counterparts ^[3]. These findings collectively demonstrate the sustained influence of urbanization on rising temperatures in the Phoenix area.

No direct statistical correlation exists for winter precipitation and April heat. The available research does not provide a direct historical statistical correlation between cumulative winter (December-February) precipitation in central Arizona and the frequency of 90°F+ days in Phoenix during the subsequent April. Furthermore, the provided sources do not quantitatively establish whether drought conditions in the preceding winter create a statistically significant bias towards warmer April outcomes in terms of 90°F+ days. The broader context indicates that the American West, including Arizona, has been experiencing a prolonged and significant drought, described as a 32-year drought that may be evolving into aridification ^[1].

Recent winters show exceptionally warm, dry conditions linked to climate change. Recent winters in Phoenix have been notably warm; for instance, the winter of 2026 was reported as the hottest on record for Phoenix ^[2], with temperatures reaching 90°F as early as February ^[3]. These record winter heat events and drier conditions are linked to broader climate change trends and specific weather phenomena such as La Niña ^[4]. La Niña conditions typically result in drier-than-average winters across the Southwestern United States, contributing to lower precipitation levels and exacerbating drought conditions.

Warmer, drier winters qualitatively suggest earlier spring high temperatures. While a specific statistical analysis linking winter precipitation totals to the frequency of 90°F+ days in the subsequent April is not presented, the general trend indicates a pattern of warmer and drier winters, often associated with drought conditions and La Niña. This qualitative observation suggests an environment conducive to early or more frequent high-temperature days in the spring, potentially leading to more 90°F+ days in April. However, without specific historical data and statistical analysis, a definitive conclusion about the correlation and statistical significance of winter drought on subsequent April temperatures cannot be quantitatively drawn from these sources.

Early 2026 projects a persistent negative PDO and La Niña conditions. The Pacific Decadal Oscillation (PDO) is anticipated to remain in a negative phase through early 2026, building upon a cycle shift observed in late 2025 ^[1]. Concurrently, the Climate Prediction Center's ENSO Diagnostic Discussion from January 2026 indicates a 70% probability that La Niña conditions will persist through the spring of 2026 ^[2].

This climate combination historically increases Southwestern US high-pressure ridges. The interaction of a negative PDO phase with La Niña conditions has historically shown a significant influence on atmospheric patterns across the Western United States. This specific pairing is linked to a heightened likelihood of persistent high-pressure ridge formation, often referred to as "heat domes," over the Western U.S. during the spring season ^[3]. For the Southwestern U.S., including areas like Arizona, this atmospheric configuration during mid-April typically corresponds with warmer-than-average temperatures and drier conditions, resulting from the enhanced stability and subsidence associated with a strong high-pressure ridge ^[3].

Predictive skill for Southwest April temperatures emerges three to six months prior. While skill is generally very limited at nine months out, some preliminary skill may develop by six months, particularly when strong large-scale climate drivers like the El Nino-Southern Oscillation (ENSO) are present. Significant predictive skill for temperature in the western contiguous United States, which includes the Southwest, is consistently observed starting from three months out. Specifically, the North American Multimodel Ensemble (NMME) demonstrates "good skill" for temperature forecasts at one-month, two-month, and three-month lead times over this region, with skill generally improving closer to the forecast period ^[1].

Critical market-moving forecasts for April temperatures stem from ECMWF and NOAA CPC. The European Centre for Medium-Range Weather Forecasts (ECMWF) releases its seasonal forecasts monthly, typically around the 8th of each month, providing long-range predictions ^[3]. For April 2026 temperatures, key ECMWF releases would be those initialized in January, February, and March 2026. The NOAA Climate Prediction Center (CPC) issues its official three-month seasonal outlooks around the third Thursday of each month ^[2]. For April 2026, the most significant CPC updates would be the January 19, 2026 release (covering February-March-April), the February 19, 2026 release (covering March-April-May), and especially the March 19, 2026 release (covering April-May-June), which offers the most immediate seasonal forecast for April ^[2]. These official outlooks consolidate information from multiple models, including CFSv2, and are widely followed for their probabilistic forecasts ^[4].