Here's the situation: Anaktuvuk is at 68.1N 2100' in the Brooks Range; the village is right on the valley floor and within one mile of the continental divide. On general principles, it seems to me that it is (barely) within the realm of possibility that IF there was a fresh snow cover and IF an unseasonably cold airmass in place AND skies cleared late evening AND winds were light that Anaktuvuk could get this cold in late June (this would be a lot more believable if it was the first few days of June).
There are historically very few weather observations from this part of the world, and the data quality from the coop observation at Anaktuvuk during this time have more than a few problems. Here is the scan of the original form for June 1967:
|Courtesy of NCDC|
If these are really observations taken at 5pm (and differences from the scheduled time of observation are hardly ever recorded by the observer on the form), the data on the 24th looks suspect: was it really 40F at 5pm on the 23rd, fell to 17F the following morning ( itself a remarkably low temperature for so late in June), then rebounded to 60F, only to be back to 35F by 5pm on the 24th? The high temperature of 44F on the 25th looks plausible. Notice too the remark concerning snow cover on the morning of the 27th, but nothing that would suggest snow on the ground on the morning of the 25th.
If we look at what was happening on the broader scale, here's the NCEP/NCARR Mean Sea-Level Pressure and 850mb temperature reanalysis for Jun 25, 1967:
|Courtesy of NCEP/NCAR|
It would be nice to have some explanation of how the -1F got to recorded, but I can't think of any offhand. So, lacking any additional evidence, my vote is: beyond reasonable doubt, the low temperature was not -1F at Anaktuvuk Pass on June 25, 1967. However, there IS a very slight chance that the all the ingredients came together and that the observation of -1F is correct.