The seasonal changes in the diurnal cycle are very much as expected, with a tiny diurnal cycle in December giving way to a substantial daily oscillation by February. According to the hourly means, the coldest hour of the day in December is 7 am AKST, which is well before the sun rises; but there is less than 0.5 °F difference from midnight to 11 am.
We could also look at the frequency with which each hour of the day records the lowest or highest temperature, and examine some histograms based on those results, but I'll leave that for another time.
As we're on the topic of short-term temperature fluctuations, it's worth noting that these have been very large in Fairbanks lately. The plot below shows the 2m temperature trace from UAF's North Campus, near Smith Lake, over the past 4 days (with a period of missing data in the middle). The 2m temperature rose from -39.4 °F on Sunday to +47.2 °F yesterday, a rise of 86.6 °F in three days. Looking at the official Fairbanks history since 1930, only two occasions saw a larger 3-day temperature rise, and both of those were in January.
At Fairbanks airport, the recent 3-day rise was 84 °F (-37 to
The diurnal temperature range has also been very large in recent days: 46 °F yesterday, which is equivalent to the largest that is typically observed in any given year. March is by far the most common month for observing the year's largest diurnal temperature variation in Fairbanks.