Regardless of the time of day you decide to fly, the ticket price will remain around the same. Book flights from Singapore City Airport to Yellowknife as you normally would.
In Singapore City Airport, there will be less rainfall in Singapore City Airport compared to Yellowknife over the next 0 days.
You can imagine temperatures to be in the 33 °C range in April. The weather in Yellowknife is generally colder than Singapore City Airport's. As flight availability is subject to become more limited as peak season approaches it is ideal to book in a timely manner.