It is another of those million euros questions: How many hours of daylight do we have in Lapland? It will depend when and where we are.
Around Decemeber and January we will experience the shortest days, and during June and July we dont switch on the lights at home.
Both periods, during the shortest days in winter and the midnight sun in summer, are very exotic for the travellers.
Check the chart in this post to see how many hours of daylight you will enjoy when you visit us. The chart is based in Rovaniemi, but it is a good reference for other destinations in Lapland too.
Source: chart from El blog de Finlandia (in Spanish)