Shifting Seasons
Climate change shows up in the calendar. Spring now arrives up to three weeks earlier across temperate regions; autumn lingers longer, with the effect intensifying toward the poles. The data on this page makes the pattern undeniable: year-by-year correlations between seasonal timing and global temperature across 28 countries, a latitude chart spanning the Arctic to the Southern Ocean, a world map of every monitored region, Kyoto's 1,200-year cherry-blossom record, and the US growing season since 1895. Different datasets, different continents, the same story.
Key Facts
Shifting Seasons Worldwide
The Global Picture
How Seasons Have Shifted
Each region's first 30 years on record are compared with the most recent 10 - tracking when monthly temperatures cross the baseline annual mean to reveal earlier springs, later autumns and shifting wet seasons.
World Map - Pick a Metric
Where the Warm-Season Shift Is Biggest (Köppen C + D Regions)
Spring / autumn crossings are only meaningful where the climate has a genuine winter, i.e. Köppen temperate (C) or continental (D) groups. Tropical (A) and arid (B) regions are ranked by wet-season metrics below.
- 1Iceland-26.5 d
- 2Mexico-21.2 d
- 3New Zealand-21.1 d
- 4Chile-20.9 d
- 5Israel-15.9 d
- 6Lebanon-15.7 d
- 7Turkey-15.7 d
- 8Northern Ireland-15.7 d
- 1Myanmar+25.5 d
- 2New Zealand+22.5 d
- 3Malawi+20.4 d
- 4Iceland+20.0 d
- 5Mexico+17.6 d
- 6Norway+17.5 d
- 7Greenland+15.6 d
- 8England SE & Central South+15.0 d
Where the Wet/Dry Rhythm Is Shifting Most (Köppen A + B Regions)
For tropical (A) and arid (B) climates the rains define the year. Onset (25% of annual rain) and end (75%) shifts together describe whether the wet window is moving, lengthening or shrinking; annual-total change is the signal that matters most for agriculture.
- 1Tajikistan+362 d
- 2Turkmenistan-357 d
- 3East Timor+356 d
- 4United Arab Emirates-346 d
- 5Oman-125 d
- 6Algeria-35 d
- 7Pakistan+25 d
- 8Tunisia-19 d
- 1New Caledonia-28 d
- 2Qatar+26 d
- 3Djibouti+23 d
- 4United Arab Emirates+22 d
- 5Nevada-20 d
- 6Saudi Arabia+20 d
- 7Estonia+16 d
- 8Afghanistan+14 d
- 1Jordan-65.1%
- 2Libya-63.4%
- 3Egypt-63.0%
- 4Syria-46.6%
- 5Morocco-41.9%
- 6Mauritania-39.7%
- 7Saudi Arabia-36.7%
- 8Algeria-33.9%
Method: baseline = first 30 complete years of record; recent = last 10 complete years. Warm-season length = months per year whose mean exceeds the baseline annual mean; spring/autumn crossings = interpolated day-of-year where the monthly climatology crosses that threshold. Wet-season onset = day of year where cumulative precipitation from 1 Jan first passes 25 % of baseline annual total. Precipitation data: GPCC Full Data Monthly (DWD, 1891–present), World Bank CCKP (CRU TS) fallback where GPCC has no coverage. Snow (water- equivalent) data: GPCC solid/liquid classification, 1982–present. Köppen codes follow Peel, Finlayson & McMahon 2007.
The Warming Fingerprint
Do the Seasons Track Global Temperature?
The shift in seasons is not random variation and is also not driven by El Niño cycles. Plot US spring arrival against global mean temperature year by year and the dots form an almost perfect line, one of the tightest relationships in the entire climate record.
This clarity comes from a dataset that does not exist anywhere else: the US EPA has averaged frost dates across thousands of weather stations every year since 1895, more than 125 years of continuous, nationwide data. The finding is not US-specific. Ninety-six percent of countries show the same direction of change, a statistical fingerprint essentially impossible under natural variability alone. The US data is the clearest window; the pattern is global.
Seasons Shift at Every Latitude
Historical Records
Kyoto, Japan: 1,200 Years of Cherry Blossom
In Kyoto, Japan, court diaries, monastery records, and weather observations have logged the day each spring when the city's cherry trees reach full bloom (満開, mankai) almost every year since 812 CE. It's the longest continuous biological record of climate anywhere on Earth, and the signal of recent warming is unmistakable.
versus Apr 15 pre-1850, a shift of 10.7 days earlier. The earliest bloom in the entire 1,200-year record is 2021 (Mar 26).
Each pink dot is one year's full-bloom date. The yellow line is a 30-year centred rolling mean. The dashed line is the pre-1850 long-term mean (Apr 15). Y-axis is reversed so that “earlier in the year” is up.
Source: Aono & Kazui (2008) and Aono & Saito (2010), via NOAA NCEI Paleoclimatology; recent decade extended from JMA Kyoto sakura observation records.
Northern Hemisphere Snow Cover
Satellites have mapped Northern Hemisphere snow cover every week since late 1966. Winter snow extent has held up reasonably well, but spring snow is collapsing: the meltout now happens weeks earlier across vast areas, exposing darker land that absorbs more sunlight and accelerates regional warming.
Spring Snow Is Shrinking, Winter Is Holding Up
Anomaly = % difference from the 1981–2010 monthly mean, averaged over the three months of each season.
Last Two Years, Month by Month
Red bars = below 1981–2010 normal, ice-blue bars = above. Updates monthly from Rutgers Global Snow Lab.
Source: Rutgers University Global Snow Lab (NOAA NESDIS satellite analyses). Climatology baseline 1981–2010.
United States
Live: How Early Is Spring Arriving Across the US?
The USA National Phenology Network runs a daily-updated model that tracks how many days early or late spring is arriving compared to the 1991–2020 average, based on the thermal thresholds that trigger leaf-out and first-bloom in temperate woody plants. During Feb–May each year, the map below updates every day.
The CONUS Growing Season
Since 1895 the contiguous-US growing season (the stretch between the last spring frost and the first autumn frost) has lengthened dramatically. The shift is largest in the West, where earlier springs and later autumns compound.
CONUS Growing-Season Length, 1895–2020
Green = longer than the 1895–2020 mean, orange = shorter. The direction of change is unambiguous from around the 1980s onward.
Source: EPA Climate Change Indicators: Length of Growing Season. Underlying data: Kunkel (2021). Coverage: 1895–2020 (Contiguous 48 states). The EPA suspended updates to this indicator after April 2021, so the series is authoritative historically but ends in 2020. We plan to supplement with current-year figures from NOAA's xmACIS in a follow-up.
Explore
Explore Climate Data
FAQs
FAQs
What does the shifting seasons page show?
How the timing and length of meteorological seasons have changed under climate change - when spring now begins, how long summer lasts, when winter snow cover starts and ends, and how these shifts vary by hemisphere and by country. The live charts and the country comparison panel above carry the current values.
How are season-shift indicators measured?
Spring onset uses the USA-NPN Spring Leaf and Bloom Index (USA) and equivalent phenological and temperature-threshold indicators elsewhere. Growing-season length uses the first and last date with daily mean temperature above a region-appropriate threshold. Snow cover uses the Northern Hemisphere snow-cover extent series from Rutgers University Global Snow Lab.
Where does the seasonal data come from?
USA: NOAA NCEI nClimDiv, USA-NPN, EPA Climate Change Indicators. Northern-Hemisphere snow: Rutgers Global Snow Lab. Country-level seasonal anomalies: Berkeley Earth, Copernicus C3S / ERA5. UK seasonal anomalies: Met Office HadUK-Grid.
What baseline is used?
Anomalies are calculated against the 1991-2020 climate normal where available (WMO standard). Some indicators (snow cover, US growing season) use longer reference periods set by the source agency; the baseline is labelled on each chart.
Are summers getting longer?
Yes. The growing season - the run of days with mean temperature above a region-appropriate threshold - has lengthened across most of the Northern Hemisphere since 1970, with the sharpest gains in the contiguous United States and northern Europe. The exact change for any one country, US state or UK region is shown live on this page in the season-length chart and the country comparison panel above; we do not bake numbers into this FAQ because they refresh annually.
When does spring arrive now compared with the past?
Spring is arriving earlier across most of the temperate Northern Hemisphere. The USA-NPN Spring Leaf and Bloom Index (USA), Met Office HadUK-Grid temperature thresholds (UK) and Berkeley Earth / Copernicus ERA5 (rest of the world) all show first-leaf and first-bloom dates trending earlier by roughly one to three weeks since 1980, depending on the region. Pick a country in the country comparison panel above to see the live spring-onset anomaly.
Why are seasonal shifts a useful climate indicator?
Annual mean temperature can mask big within-year changes. Earlier spring leaf-out, longer frost-free windows, later first-snow dates and shorter snow-cover seasons all change the environment for crops, pests, pollinators and water supply long before the headline temperature anomaly looks alarming. They are also independent of the choice of climate baseline, which makes them a good cross-check on the temperature record.
What do the coloured dots on each seasonal bar represent?
Each dot marks one calendar year. Its position along the bar shows how that season's timing shifted relative to the 1991-2020 baseline (earlier to the left, later to the right). Its colour shows how warm that specific year was globally, keyed to the NOAA global surface temperature anomaly scale: deep blue for cooler-than-baseline years through to deep red for the hottest. This lets you see at a glance that the most recent years (the reddest dots) are also the ones with the most shifted seasons, revealing the direct link between overall warming and seasonal timing change. The Auto-Stretch toggle rescales the colour range to the spread within each individual country or indicator, which can make smaller signals easier to read.
Which countries show a shifting wet season?
The wet-season shift chart appears for countries where a distinct rainy season can be identified from the temperature and precipitation record - primarily tropical and subtropical countries across South and Southeast Asia, sub-Saharan Africa, Central America and northern Australia. Temperate countries with year-round rainfall distribution (most of Europe, for example) show the warm-season chart instead. The data source is Copernicus ERA5 via Berkeley Earth country-level aggregates.
How often is this page updated?
Annual indicators (growing-season length, snow-season length) refresh once a year as the source agencies publish them. Monthly indicators refresh on the same monthly cadence as the rest of the site, typically in the first half of each month.