CrazyWeather Issue

16:38:26 [INFO] [CrazyWeather] Enabling CrazyWeather vC7.5_4
16:38:26 [INFO] [CrazyWeather] CrazyWeather has been updated. Updating language files.
16:38:26 [SEVERE] Error occurred while enabling CrazyWeather vC7.5_4 (Is it up to date?)
java.lang.NullPointerException
        at de.st_ddt.crazyweather.WorldWeather.save(WorldWeather.java:81)
        at de.st_ddt.crazyweather.CrazyWeather.save(CrazyWeather.java:70)
        at de.st_ddt.crazyplugin.CrazyPlugin.onEnable(CrazyPlugin.java:194)
        at de.st_ddt.crazyweather.CrazyWeather.onEnable(CrazyWeather.java:45)
        at org.bukkit.plugin.java.JavaPlugin.setEnabled(JavaPlugin.java:215)
        at org.bukkit.plugin.java.JavaPluginLoader.enablePlugin(JavaPluginLoader.java:337)
        at org.bukkit.plugin.SimplePluginManager.enablePlugin(SimplePluginManager.java:381)
        at org.bukkit.craftbukkit.CraftServer.loadPlugin(CraftServer.java:256)
        at org.bukkit.craftbukkit.CraftServer.enablePlugins(CraftServer.java:238)
        at net.minecraft.server.MinecraftServer.t(MinecraftServer.java:381)
        at net.minecraft.server.MinecraftServer.a(MinecraftServer.java:368)
        at net.minecraft.server.MinecraftServer.init(MinecraftServer.java:197)
        at net.minecraft.server.MinecraftServer.run(MinecraftServer.java:432)
        at net.minecraft.server.ThreadServerApplication.run(SourceFile:492)