No, it's not global warming, but for some reason Sweden is a hotbed of great Java developers and great Java conferences in the winter. First, all three Swedish Java Champions are on Computer Sweden's 100 Best Swedish Developers List. You can read the full Sweden's Top 100 Developers article *if* you can read Swedish (or want to use Google Translate). Congratulations to: 

Jonas Bonér, CTO Typesafe

Skills: In recent years worked with solutions for scalability and availability. Previously, most between programs and compilers.

Other qualifications: Located behind the framework Aspectwerkz and Akka platform for developing parallel, scalable and fault-tolerant software in Scala and Java.

Rickard Oberg, Neo Technology

Skills: Java, and the framework in Java EE and graph databases.

Other qualifications: Founder of open source projects Xdoclet and Webwork. The latter is now called Struts second Rickard Oberg wrote the basics of the application server JBoss. Founder of Senselogic and architect of CMS and portal product SiteVision. Launched frameworkQi4j. Been a speaker at Java Zone JavaPolis, Jfokus, Øredev.

Skills: Java. Good at agile system development methods and architecture.

Activity: telecom, banking, finance and insurance.

Other qualifications: Runs Javaforum Stockholm. Arranges the conference Jfokus. 

Frequent speaker at major international conferences such as JavaOne. Holds the title Java Champion.

Also, Sweden is home to some top-notch Java Developer conferences during the Winter:

jDays Gothenburg, Sweden, Dec 3-5. jDays, a dynamic Java developer conference, comes to Gothenburg. In addition to conference and presentations, visitors can join any courses in Java and related technologies for free. 

Jfokus Stockholm, Sweden, Feb 4-6. Jfokus is the largest annual conference for everyone who works with Java in Sweden. The conference is arranged together with Javaforum, the Stockholm JUG. 

Thanks to all the Java community who keep the Java hot in Sweden!