Climate Shift Index Alert•April 15, 2025
Spring warmth, fueled by climate change, threatens Norway's Easter holiday
Warmer-than-normal spring temperatures fueled by climate change are disrupting Norway’s spring, making Easter holiday ski trips increasingly uncertain. From late March through mid-April, heat driven by human-caused climate change has gripped much of the country, and similar conditions are set to continue at least through April 18.
Note: This event may continue beyond April 18. Use the Global Climate Shift Index map to stay updated on heat in your region.
How has climate change influenced this unusual warmth?
Daily average temperatures reached Climate Shift Index (CSI) levels of 5 across most of Norway in late March and the first half of April (March 20-April 14).
A CSI level 5 indicates that human-caused climate change made these unseasonably warm conditions at least 5 times more likely, signifying an exceptional climate change event.
Temperatures across Norway were much higher than typical spring conditions this year, reaching up to 13°C above normal.
With above-average temperatures forecast across much of Norway in the coming days, precipitation is expected to fall predominantly as rain rather than snow. This shift, combined with sustained above-freezing temperatures, is likely to accelerate snowmelt.
Similar conditions are expected over the next several days (April 15-18). CSI levels of at least 5 are expected across most of south, west, central, and east Norway, impacting Ålesund, Oslo, Drammen, Bergen, Trondheim, Stavanger, Steinkjer, and other cities.
Climate change made these warm conditions at least five times more likely.
City | Number of days at or above freezing (Tmin > 0°C) | Highest temperature anomaly (°C above normal) | Date of highest temperature anomaly | Temperature on day with highest anomaly (°C) | Number of days strongly influenced by climate change (CSI =3) | Number of days exceptionally influenced by climate change (CSI =5) |
|---|---|---|---|---|---|---|
Sandvika | 18 | 12.6 | April 3 | 18.2 | 19 | 16 |
Drammen | 17 | 11.8 | April 3 | 18.0 | 19 | 15 |
Oslo | 20 | 11.8 | April 3 | 17.8 | 19 | 15 |
Asker | 19 | 11.5 | April 3 | 18.1 | 19 | 19 |
Lørenskog | 19 | 11.4 | April 3 | 17.9 | 19 | 14 |
Oppegård | 19 | 11.0 | April 3 | 17.4 | 20 | 18 |
Trondheim | 25 | 10.4 | April 2 | 16.7 | 13 | 8 |
Sandefjord | 21 | 10.2 | April 12 | 17.8 | 19 | 14 |
Sarpsborg | 24 | 8.3 | April 12 | 17.1 | 16 | 10 |
Tønsberg | 24 | 6.2 | April 3 | 12.3 | 19 | 16 |
*Table data for March 20-April 14 |
What do experts say?
Dr. Kristina Dahl, Vice President of Science at Climate Central:
“The unusual warmth across Norway this spring is a clear signal of how climate change is reshaping life in the Nordics—from disrupted Easter traditions to stressed ecosystems,” said Dr. Kristina Dahl, Vice President of Science at Climate Central. “When temperatures reach a Climate Shift Index level of 5, it means climate change isn’t just a background influence—it’s the main reason these conditions are happening. If the world doesn’t rapidly cut fossil fuel emissions, the Easter skiing tradition could be lost for future generations.”
To request an interview with a Climate Central scientist, please contact Abbie Veitch at aveitch@climatecentral.org.
How do we know climate change is influencing this heat?
The Climate Shift Index uses peer-reviewed methodology and real-time data to estimate how climate change has increased the likelihood of a particular daily temperature.