US Northwest Climate – May 2026 Update
Top States: Washington, Oregon, and Idaho
This month in numbers
The US Northwest experienced a significantly warm May, with a 1-month temperature anomaly of +2.60°C compared to the 1961–1990 average. The warming trend extends to longer periods, with a 3-month anomaly of +2.55°C and a 12-month rolling anomaly of +2.51°C. Globally, the US Northwest was not among the top 10 warmest regions for May, which were dominated by countries in Central and West Asia.
Hottest & coolest US states
Within the US Northwest, all three states experienced considerably warmer-than-average conditions in May. Oregon (US Oregon) led the warming with an anomaly of +2.75°C, followed closely by Washington (US Washington) at +2.60°C, and Idaho (US Idaho) at +2.41°C. There were no strikingly cool states within the US Northwest region this month.
What's driving change?
The current climate pattern in the US Northwest is strongly influenced by the developing El Niño phenomenon. The current ENSO state is Neutral, with an anomaly of +0.48°C for March-May 2026. However, forecasts indicate a rapid transition to El Niño, with a 97% probability for May-July and a 99% probability for June-August, strengthening to 100% by August-September. El Niño typically brings warmer and drier conditions to the Pacific Northwest, increasing the risk of heatwaves and wildfires, and potentially leading to reduced mountain snowpack in the coming winter. Oregon has already declared a wildfire emergency in nine counties in May, highlighting the immediate impacts of these warmer and drier conditions. This pattern is consistent with the warming driver of seasonal shifts, as winters are warming faster at high latitudes.
Looking ahead
The seasonal outlook suggests that warmer and drier than normal conditions are likely to persist across the US Northwest in the coming months, with El Niño expected to strengthen further into the autumn and winter.
Generated by Gemini from climate data and web sources
At a Glance
Temperature – Average
Climate Map – USA
Source: NOAA Climate at a Glance — US states & climate regions (tavg, pcp). Anomalies are vs the 1961–1990 baseline (temperature) or 1991–2020 (rainfall). See methodology.
Hottest & Coolest in US Northwest this Month
1-month anomaly vs 1961–1990 across the 3 members we cover. Click a name to open its profile.
Warmest
- 1.🇺🇸Oregon+2.75°C
- 2.🇺🇸Washington+2.60°C
- 3.🇺🇸Idaho+2.41°C
Coolest
- 1.🇺🇸Idaho+2.41°C
- 2.🇺🇸Washington+2.60°C
- 3.🇺🇸Oregon+2.75°C
Member States
Year-on-Year Trends
The 4byo Climate Helix – US Northwest
NOAA Climate at a Glance — regional tavg / pcp (monthly absolutes).
US Northwest – Monthly Temperature – All Years
NOAA Climate at a Glance — regional tavg / pcp (monthly absolutes).
Records – US Northwest
NOAA Climate at a Glance — regional tavg / pcp (monthly absolutes).
Shifting Seasons
Warm / cold seasonsHow spring and autumn have shifted in US Northwest. Spring is defined as the date monthly temperatures first rise above the long-term annual mean (7.3°C, from 1950–1979); autumn is the date they fall back below it. Temperature swings 21.0°C peak-to-peak across the year - a classic four-seasons rhythm.
Baseline vs recent monthly temperature climatology. Biggest warming: Aug (+1.9°C).
NOAA Climate at a Glance — regional tavg. Baseline: first 30 yrs on record. Recent: last 10 yrs on record.
Rainfall & Rain Days – Totals
Climate Systems
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Emissions & Energy
Explore
Explore Climate Data
Data Sources
Data Sources for US Northwest
Every figure on this page is sourced from official, openly published climate datasets. Anomalies are calculated against the 1961–1990 baseline (temperature) and 1991–2020 (rainfall, sunshine, frost) - see the Methodology & Sources page for the complete dataset list and update calendar.
FAQs
FAQs
How is the climate in US Northwest changing?
US Northwest is warming in line with the rest of the world. The page above shows the latest monthly temperature anomaly versus the 1961-1990 baseline, the long-term annual trend, and the region's rank in the historical record. The headline panel also shows the long-term trend rate per decade and the warmest and coolest years on file.
Where does the climate data for US Northwest come from?
Climate data for US Northwest comes from authoritative climate datasets including national meteorological services and peer-reviewed reanalyses, refreshed every month, when the upstream temperature and rainfall data are refreshed.
What is the climate baseline used on this page?
Anomalies on this page are calculated against the 1961-1990 climatological baseline, which is the standard reference period used by the Met Office, NOAA, IPCC and most national climate services. Some panels also show the source-native 1901-2000 (NOAA) or 1991-2020 (WMO) baselines for verification. See Methodology & Sources for the full reference.
Which areas does the US Northwest climate data cover?
The US Northwest climate profile covers Washington, Oregon, Idaho and surrounding areas. NOAA Northwest - ID, OR, WA
How often is the US Northwest climate update refreshed?
The US Northwest climate update is refreshed monthly, typically a few days after the previous month closes and the upstream provider (Met Office HadUK-Grid, NOAA Climate at a Glance, Copernicus ERA5 or the Global Carbon Project) publishes its update. See the Climate Rankings for cross-region comparisons.