Currently, there are several retrospective analyses of weather conditions during the tragic events of 1959 related to the death of Igor Dyatlov's group of hikers. At first glance, the most professional analysis was conducted by G.B. Pigoltsina, a leading researcher at the A.I. Voeikov Main Geophysical Observatory and Doctor of Geographical Sciences (2019), who notes that on February 1, "At 6 p.m., the temperature at the tent site was -17ºC, and at 8 p.m., -18.5º. It was at this time that a cold front passed over the area, and the influx of cold air led to a sharp drop in temperature. "The temperature at the tent site was already -22.5º at 11 p.m. ..." (pp. 65, 66), and the wind speed on the open mountain slope ("plateau") was about 10 m/s; in the period from 1 p.m. on February 1 to 7 p.m. on February 2, the maximum wind speed was 14.4 m/s (at 9 a.m. on February 2), while it is noted that gusty winds, which could occur between the observation times at the weather stations, cannot be ruled out.

This study may contradict the study of a professional meteorologist Vladimir Moshiashvili (leading engineer of the Russian State Hydrometeorological University), who noted that “In the area of ​​the main ridge on the eastern side, a “bora” type phenomenon could have been observed – a fall of heavy cold air downwards as it passes over the ridge with an increase in wind even to hurricane force of 20–30 m/s below the ridge” (p. 91 Buyanov, Slobtsov, 2011).

The bora hypothesis aligns well with the testimony of local residents, who noted periodic hurricane-force winds in the area where the Dyatlov group's hikers died, as well as severe weather conditions around the same time as the event. For example, from the interrogation of the acting engineer Mihail Dryakhlykh, March 5, 1959: "From January 24 to February 1, 1959, included, I was traveling on business to 41st district... The district is 40 km straight north from village of Vizhay... During the last days of my trip there was strong wind with a snowfall in the forest and the roads were heaped up with snow and needed a thorough cleaning with bulldozers. When I went home, there was still strong wind and the temperature was colder than 30° below zero. I have lived here for 32 years and we have rarely had winds like this." Case files 40-41. Or the testimony of Vizhay forester Ivan Pashin, March 7, 1959: "I believe that at this time when we were there was a strong wind and blown off the mountain. Around the time when hikers were killed even in the village of Vizhay was a strong wind and storm, from which the children were falling down. I am a hunter from an early age and I know these places well, and I remember that there were cases of strong winds when people got killed. I myself had to sit up strong winds for 6 days without food in the hollows expecting when the winds would subside." Case file 50

Research by candidate of biological sciences Aleksander Konstantinov (2013) confirms the possibility of bora, as well as other foehn phenomena, and field studies have made it possible to find numerous evidence of periodic hurricane-force winds of a northwesterly direction arising at the site of the tragic events of 1959 (Konstantinov, 2023). Of the published studies, Vladimir Borzenkov's (2018) analysis of weather conditions is also noteworthy. It is of interest primarily for its direct observations of weather conditions during several winter expeditions conducted jointly with Aleksander Alekseyenkov from 2012 to 2016. The tragic events of 1959, involving the deaths of nine tourists in the mountain tundra of the Northern Urals, occurred in winter, when the harsh climatic conditions of these regions are at their most severe. For this reason, and given that most of the tourists died from freezing, reconstructing the weather conditions at the time of this incident is the most important task in establishing the causes of this tragedy. For some reason, no analysis of weather conditions was conducted in 1959, and the workbooks of the head of the search operations, Evgeniy Maslennikov, contain only some weather data for February 1 from the Burmantovo and Ivdel meteorological stations. These data contain extremely interesting information about the air temperature in Burmantovo at 11 p.m. local time, which was -5ºC, which is inconsistent with the research of G.B. Pigoltsina, since at this time, according to her research, after the passage of the cold front, the air temperature was about -22.5ºC (near the tent), and in the village of Burmantovo, located only 75 km to the southeast, there should have been a comparable temperature or slightly higher, since the cyclone moved from northwest to southeast (Pigoltsina, 2019) at an average speed of about 40 km/h (s. 91 Buyanov, Slobtsov, 2011) and the cold front noted by her would have already reached or passed this settlement in 23:00, in addition, according to this author’s research, the air temperature near the tent was already -14ºC at 13:00 and continued to gradually decrease until 23:00.

Fig. 1. Some information on weather conditions at the Burmantovo meteorological station at the end of February 1, 1959, obtained by the head of search operations, Evgeniy Maslennikov. Information provided by Vladislav Karelin.

Apparently, well-founded doubts about the accuracy of G. B. Pigoltsina's weather analysis, as well as the fact that the primary meteorological data from these studies have not been published, leave the problem of determining weather conditions during the tragic events of 1959 in the Northern Ural Mountains unresolved. To resolve this issue, meteorological data from nearby weather stations is primarily needed. We were able to find the following publicly available meteorological data:

• Hourly weather data for February 1, 1959, and daily data for February 1959 from the Burmantovo weather station, obtained by E. Koskina
• Daily data for some weather stations on the website https://thermo.karelia.ru
• Weather maps on the website https://www.wetterzentrale.de
• Hourly and daily data for almost all the world's weather stations on the National Oceanic and Atmospheric Administration (NOAA) website https://www.ncei.noaa.gov/products/land-based-station/integrated-surface-database (hourly data), despite the global coverage of weather stations, this data contains gaps.
• Hourly weather data for some airports https://ru.weatherspark.com, in particular for airports in the cities of Ukhta, Amderma, and Salekhard; in addition to the main deadlines, there are additional deadlines.
• daily data for some weather stations on the website: https://www.tutiempo.net

The most informative data are those from weather stations located near the sites of the 1959 events, as well as similar data from weather stations through which the Icelandic cyclone passed, determining weather conditions during the tragic events of 1959. For some of these weather stations, the NOAA database lacks hourly data for the period from January 30 to February 2 (this period covers the days immediately before and after the tragic events). Therefore, we requested data from the database of the All-Russian Research Institute of Hydrometeorological Information - World Data Center (VNIIGMI-WCD) for seven weather stations (see Fig. 2). VNIIGMI-WCD agreed to sell us this data. We purchased this data and decided to make it open and accessible to everyone (see Tables 1-7). These data include the following hourly indicators for seven weather stations (Burmantovo, Ust-Unya, Yaksha, Verkhniy Shchugor, Ust-Shchugor, Petrun and Khoseda-Hard): 1) relative humidity, 2) water vapor pressure, 3) air pressure at sea level, 4) saturation deficiency, 5) barometric tendency ‒ curve type, 6) barometric tendency value, 7) horizontal visibility, 8) cloud base height, 9) total cloud cover amount, 10) low cloud cover amount, 11) wind direction, 12) wind speed, 13) precipitation total, 14) air pressure at station level, 15) soil surface temperature, 16) weather at observation time, 17) air temperature, 18) atmospheric phenomena, 19) upper cloud shape, 20) middle cloud shape, 21) shape cumulus clouds, 22) stratiform stratocumulus clouds, 23) rain clouds, broken clouds, 24) dew point. It should be noted that in 1959, observations at Soviet weather stations were not conducted at synchronous times, as they are now, but at climatological times of 1, 7, 13, and 19 hours mean solar time; these are the times indicated in the tables below.

Fig. 2. Weather stations for which hourly data were obtained from the VNIIGMI-MDC database for the period from January 30 to February 1, 1959 (marked with red circles with black dots) and some other nearby weather stations (hourly data for these stations is available in the NOAA database). Marked with "X" is the location of the tent where it was found in 1959. Source of space image Google Earth pro.