Illinois Climate – June 2026 Update
Top 5 Cities: Chicago, Aurora, Rockford, Joliet, and Naperville
This month in numbers
Illinois experienced its 8th warmest April-June period on record, with an average temperature of 18°C, a significant 1.4°C above the 1961–1990 baseline. June 2026 saw particularly heavy rainfall, ranking as the 5th wettest June on record with 181.36 mm of precipitation, an anomaly of +82.8 mm compared to the baseline. Globally, land temperatures in June 2026 were the 3rd warmest on record, at 16.46°C, an anomaly of +1°C. The April-June 2026 global land temperature also ranked as the 2nd warmest on record, at 15.74°C, a +1°C anomaly.
What changed
The past three months in Illinois have been notably warmer than average, with the April-June period ranking as the 8th warmest in 77 years of records. This trend aligns with a broader national picture of warmer conditions, as the contiguous United States also experienced above-average temperatures in June 2026, with a +1.6°C anomaly. Illinois's average temperature for June was 0.2°C above the 1961-1990 baseline, placing it 214th out of 234 regions globally for its 1-month anomaly. The state's 3-month anomaly of +1.4°C places it 120th globally.
What’s driving change?
Illinois has experienced a significant concentration of extreme weather events recently. Four wildfire events were logged between late June and early July, representing 100% of the annual total for the past 12 months, which is an unusual concentration for the region and season. Additionally, one flood event occurred between May and July, also representing 100% of the annual total. These events are consistent with a pattern of seasonal shifts, where the Midwest has experienced increasingly erratic rainfall patterns and longer stretches of hot, dry weather in recent years. This June, Illinois also saw historic tornado activity, with 91 preliminary tornado reports, setting a new June record for the state. Governor Pritzker declared 11 Illinois counties disaster areas due to severe weather and flooding from March through June, highlighting the widespread impact of these events.
Looking ahead
The NOAA Climate Prediction Center's outlook for July-September 2026 suggests a potential for cooler than normal temperatures in the Upper and Mid Mississippi River Valleys, with above-average precipitation expected in the Middle Mississippi and Ohio River Valleys.
Sources:
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.
Year-on-Year Trends
The 4byo Climate Helix – Illinois
Data: NOAA National Centers for Environmental Information. Baseline: first 30 yrs on record. Recent: last 10 yrs on record.
Illinois – Monthly Temperature – All Years
Data: NOAA National Centers for Environmental Information. Baseline: first 30 yrs on record. Recent: last 10 yrs on record.
Records – Illinois
NOAA National Centers for Environmental Information - Anomalies vs 1901-2000 mean
Shifting Seasons
Warm / cold seasonsKöppen Dfa · ContinentalHow spring and autumn have shifted in Illinois. Spring is defined as the date monthly temperatures first rise above the long-term annual mean (10.7°C, from 1950–1979); autumn is the date they fall back below it. Temperature swings 28.4°C peak-to-peak across the year - a classic four-seasons rhythm.
Baseline vs recent monthly temperature climatology. Biggest warming: Mar (+2.7°C).
Data: NOAA National Centers for Environmental Information. Baseline: first 30 yrs on record. Recent: last 10 yrs on record.
Rainfall & Precipitation
Rainfall & Rain Days – Totals
Emissions & Energy
Explore
Explore Climate Data
Data Sources
Data Sources for Illinois
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 Illinois changing?
Illinois 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 Illinois come from?
Climate data for Illinois comes from NOAA Climate at a Glance (temperature and precipitation), 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 Illinois climate data cover?
The Illinois climate profile covers Chicago, Aurora, Rockford, Joliet and surrounding areas. Illinois climate data from NOAA Climate at a Glance
How often is the Illinois climate update refreshed?
The Illinois 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.