Nesterov index is used officially in the Ukraine and Russia for fire danger assessment. As for me, it's the simplest climate related index. There are a lot of modifications.

Study can be done to formulate such an index for specific area. Climatic or weather variables affecting forest fires will include dryness or wetness, wind speed and direction, precipitation, temperature, thunderstorm, types of forests, and human activities...

McArthur Forest Fire Danger Index in Australia. More info about this and the Canadian Index here. It is being updated at present, partly because its upper part is unconstrained and recent extreme conditions have pushed it beyond its design parameters.

http://www.bushfirecrc.com/publications/citation/bf-3549

The most widely used index is the Canadian Fire Weather Index (FWI). It is under used in boreal, temperate, and even some tropical regions. It requires as input 12:00h values for air temperature, relative humidity, wind speed, and precipitation over the preceding 24 hours. It outputs 3 sub-indices that estimate different aspects of potential fire behavior, plus an integrated index (FWI itself).

There is a lot of literature on FWI, as you can see through this Google Scholar search: https://scholar.google.pt/scholar?hl=en&q=fire+weather+index+FWI&btnG=&as_sdt=1%2C5&as_sdtp=

Good luck with your work

JP

Dear All,

It seems that Sielianinov index  isn’t very popular and probably not as efficient as indexes you suggested. Only problem is to get the proper data. I am aiming at reconstruction of the meteorological conditions of the past fires and most of the data are missing especially things like duff moisture or even relative humidity.

I am glad you participated in the discussion. You pointed at interesting facts. Thank you very much.

The Canadian Fire Weather Index is the most widely used worldwide. Here in Brazil usually researchers use the "Fórmula de Monte Alegre".

You have to test the common used indexs (such as Nesterov, FWI, McArthur FFDI, Angstron, Rodrigues and Moretti, USA NFDRS, and others) to see which is the most appropriate for your study region. You also can build a new model.

If you want more information about building a new model, read this article:

https://www.researchgate.net/publication/271144178_DEVELOPMENT_OF_A_FIRE_DANGER_INDEX_FOR_EUCALYPT_PLANTATIONS_IN_THE_NORTHERN_COAST_OF_BAHIA_BRAZIL?ev=prf_pub

Article Development of a fire danger index for eucalypt plantations ...

Never heard about the Sielianinov index. There are many indexes out there, including those that just reflect the atmospheric influence on fuel moisture, or fuel moisture + wind speed, like Angstrom or Nesterov. These are indicators of ignition potential or, partially, fire spread potential. So, the best indexes are those that reflect current atmospheric conditions plus drought and are cumulative. The Canadian FWI, US NFDRS and Australian indexes do this and indicate levels of fire behaviour, although they can simply be used to indicate correlation with fire activity. Ideally, the classes should be adjusted to reflect fire behaviour levels in relation to firefighting difficulty. In Australia the fire danger system is being updated to also reflect the likelihood of events than can happen after peak fire weather hour, e.g. shifts in wind direction (due to cold fronts or thunderstorms) and the influence of atmospheric instability that is usually associated with major conflagrations and fire storms.

The Sielianinov Hydrothermal Index is (was) used primarily to support decision-making in agricultural management in north-eastern Europe (occasionally in other countries such as Cyprus). It was not conceived or tested for fire hazard assessment. For that, the best options have already been advanced here. I just add a recently published index that may eventually be useful, the Hot-Dry-Windy Index (doi: 10.3390 / atmos9070279).

Portugal has been using the Canadian Forest Fire Weather Index System (CFFWIS) for about twenty years, being responsible for its daily calculation and monitoring the Portuguese Weather Service, designated by the Portuguese Institute of the S@ea and Atmosphere, IPMA. This index, generically referred as Fire Weather Index, FWI, has been used by the National Emergency and Civil Protection Authority, ANEPC, and by Portuguese firefighters, giving very good feedback of their practical use and results.

Despite this, this index lacks two important components, one of which concerns the non-incorporation of the structural component and the other the lack of an indicator of atmospheric stability and other meteorological phenomena of local or regional scale not translated in the index. To overcome these limitations, which are so important to the behaviour and intensity of fires, the following procedures are adopted at IPMA: 1) Conjunctural and Meteorological Risk Map - RCM, this risk index is the result of risk matrix comprising both daily value of the FWI and a structural component (climatology of fires, burnt areas, land cover...) prepared annually by the  Forest and Nature Conservation Conservation Institute of the nature and forests (https://www.ipma.pt/export/sites/ipma/bin/docs/relatorios/meteorologia/nt-rcm.pdf), ICNF; 2) . Ilda Novo Simões, Alvaro Silva, Pedro Silva , Miguel Carmo.

Paulo Fernandes For your information.

It was a hydrothermal inex used in the Polish method of forest fire hazard classification - until 2011.

The value of the Sielaninov (k) index calculated from the formula:

k=10P/t

P - the sum of atmospheric precipitation for the analyzed period (data from own meteorological station or the nearest national system) [mm],

t - the sum of average daily air temperatures in the analyzed period, taking into account only positive temperature (data from the closest weather station) [° C].

The calculations are made for the individual months from April to October, from the period of at least the last 5 years.

*The illustration shows an exemplary spatial arrangement of the values of the Sielianinov hydrothermal index

Ryszard J. Kaczka In the old method of determining the category of forest fire hazard in Poland (for the area of the Forest District, once every 10 years for planning purposes), the Sielianinov index was used.

In the new classification rules currently in force in Poland, a significant change was made, because the Sielianinow hydrothermal index was abandoned in determining the fire hazard (it was replaced with relative air humidity and pine litter humidity*, the condition of which determines the possibility of fire initiation in the forest). These are climatic factors and they are more reliable than the above-mentioned hydrothermal index.

*More precisely: Average relative air humidity at 9.00 am (measurement at a height of 0.5 m) and the percentage share of days with pine litter moisture at 9.00 am lower than 15% in a last five-year period.

The climatic index is one of 4 (next to forest stand, anthropogenic and fire history) used in the qualification.

Thanks a lot for you advices. It looks like the method has been improved over time and as Jan Kaczmarowski pointed out even changed to better reflect the real hazard. I am interested in past fires investigation using tree rings and by definition working with loner time series. So, the additional question is how comparable are this indexes?

Ryszard J. Kaczka In the conditions of the Central European Plain (Poland), these studies are limited to selected places where stands with a sufficiently long history have been preserved. One of the important examples of such analyzes from Poland are those made in the Białowieża Forest - It is a place where you can find forests that are little transformed and relatively long-lived, unlike other forests in my country.

Article A 350-year tree-ring fire record from Białowieża Primeval Fo...

Thread Index estimation can be one of the best approaches