US Northwest Climate – August 2026 Update
Top States: Washington, Oregon, and Idaho
Summary
The US Northwest endured an exceptionally warm August, with regional average temperatures standing more than two degrees Celsius above the long-term baseline. Severe drought conditions and intense heat combined to fan historic summer wildfires across the region, destroying hundreds of homes in suburban Washington and scorching vast stretches of Oregon rangeland. The persistent heat pattern arrives alongside a moderate El Niño forecast to peak at Very Strong between August and October, with warmer and drier conditions expected to persist across the region in the coming months.
This month in numbers
During August, the US Northwest recorded a 1-month temperature anomaly of +2.19°C compared with the 1961–1990 baseline. The 3-month anomaly reached +1.79°C, while the 12-month rolling figure rose to +2.43°C, marking a sustained period of elevated temperatures. On the global stage, the region fits into a broader North American warming trend, where 6 of the top 10 warmest territories over the past 12 months were US states.
Hottest & coolest US states
Warmth was widespread across the region, led by US Idaho at +2.54°C above average and US Oregon at +2.28°C. Even US Washington, the coolest member of the group during the month, registered a notable +1.50°C anomaly.
What's driving change?
The elevated temperatures were amplified by , as parched soils lost the ability to cool the lower atmosphere through evaporation, exacerbating regional heat and drought. Atmospheric conditions were also influenced by the tropical Pacific, where ENSO sits in a moderate phase with a 3-month Relative Niño Index anomaly of +1.36°C. Historically, El Niño events introduce a modest tendency towards milder and drier winters across the Pacific Northwest, though winter snowpack impacts remain variable. Meanwhile, severe hydrological deficits continue to impact the region, where all of US Northwest's 1 flood this year has happened in the past month, as tracked at Extreme Weather tracker.
Looking ahead
Seasonal outlooks from NOAA favour warmer and drier than normal conditions persisting across the Northwest through the autumn months.
Generated by Gemini from climate data and web sources
At a Glance
Temperature – Average
Long-Term Trends
Climate Insights – US Northwest
Precipitation, Sunshine, Frost and Snow are converted to standard deviations from their own average so they can share an axis with Temperature anomalies.
NOAA Climate at a Glance - regional tavg / pcp / tmax / tmin
Heatwave Days – US Northwest
Warm Spell Duration Index (WSDI) - days in a 6+ day run above the local 90th-percentile temperature for that time of year.
Data: World Bank Climate Change Knowledge Portal (ERA5-derived), aggregated by 4BYO across member states. Refreshed roughly 1-2x/year, ~7-8 months behind present.
Climate Map – USUnited States
Source: NOAA Climate at a Glance — US states & climate regions (tavg, pcp), plus GPCC (Snow, water-equivalent). Anomalies are vs the 1961–1990 baseline. 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.🇺🇸Idaho+2.54°C
- 2.🇺🇸Oregon+2.28°C
- 3.🇺🇸Washington+1.50°C
Coolest
- 1.🇺🇸Washington+1.50°C
- 2.🇺🇸Oregon+2.28°C
- 3.🇺🇸Idaho+2.54°C
Year-on-Year Trends
The 4byo Climate Helix – US Northwest
NOAA Climate at a Glance — regional tavg / pcp (monthly absolutes).
Monthly Temperature – US Northwest
Background lines show the last 40 years (plus the record year and its opposite, wherever they fall).
NOAA Climate at a Glance — regional tavg / pcp (monthly absolutes).
Records – US Northwest
NOAA Climate at a Glance - regional tavg / pcp - Anomalies vs 1901-2000 mean
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.
Climate Systems
Loading ENSO tracker…
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.
US 9-region temperature and precipitation series (1895–present).
US state-level CO₂ emissions and electricity generation mix by fuel source. Energy Information Administration.
Frost Days and Heatwave Days (Warm Spell Duration Index), ERA5-derived. World Bank Climate Change Knowledge Portal.
Monthly snow water-equivalent, Global Precipitation Climatology Centre (DWD).
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.
What counts as a Heatwave Day on the US Northwest climate page?
Heatwave Days use the Warm Spell Duration Index (WSDI) - the WMO/ETCCDI-standard heatwave measure: days that are part of a run of 6 or more consecutive days above the local 90th-percentile temperature for that calendar day. The 90th-percentile threshold varies by time of year (a hot day in January is judged differently to one in July) but is fixed to the 1961-1990 baseline for every year shown - it does not shift as the climate warms, which is why Heatwave Days trend upward over time.
Does the US Northwest climate page include frost and snow data?
Yes. Frost Days (days with a minimum temperature below 0°C, World Bank CCKP) and snow water-equivalent (GPCC) are shown alongside temperature and precipitation, each measured against the 1961-1990 baseline where a like-for-like historical comparison is available.