The currency used in Norway is the Norwegian Kroner. It’s not really necessary to have a lot of Norwegian Kroner as credit cards are the most common payment method in Norway. Credit cards are accepted everywhere and preferred in most cases. MasterCard and Visa credit cards are the most universal. If you have a credit card with no international transaction fee it will be your best option.
It’s very easy to find WiFi in Norway and a Norwegian/European cellular plan is not required. You can easily stay connected using WhatsApp, Signal, Viber, or your favorite messaging app. Airalo is a EU cellular plan that may be an option if you would prefer to have cellular during your trip.
June in Oslo tends to bring mild, pleasant summer days with lots of daylight. Daytime temperatures often hover between 15-22 °C (60-72 °F), while evenings and early mornings can be a bit cooler, dropping to around 8-12 °C (46-54 °F). Rain is possible, but showers are usually light and intermittent.