Geomagnetic storms, as part of the Sun-Earth relations, are continuously monitored with different indices and scales. These indices have some scale thresholds to quantify the severity or risk of geomagnetic disturbances. However, the most usual scale thresholds are arbitrarily chosen. In this work we aim to quantify the range of the thresholds through a new method. These new thresholds are based on statistical distribution fitting. <br><br> The data used are from a regional real-time high-cadence geomagnetic index, named <i>LDiñ</i>, and its derivative, <i>LCiñ</i>. We considered the negative part of <i>LDiñ</i>, as significant for geomagnetic disturbances; and the absolute value of <i>LCiñ</i>, significant for geomagnetically induced currents. Then we look for the best fit for different statistical continuous distributions applied to these indices. <br><br> The method yields that the beta prime is the most suitable functions for negative values of <i>LDiñ</i>, whereas power-law and Johnson-SU are the best fits for <i>LCiñ</i> and the whole distribution, respectively. We define new thresholds for intense, very intense and extreme geomagnetic disturbances as the intersects between these best fit distributions and the index complementary cumulative distribution function. <br><br> Then, thresholds for the negative part of <i>LDiñ</i>, are −100 nT, −205 and −475 nT. The thresholds for the absolute value of <i>LCiñ</i>, are 6, 18 and 32 nT min<sup>−1</sup>. The thresholds defined here provide criteria to assess the vulnerability to geomagnetic activity on design or mitigation purposes. <br><br> These threshold definitions will be applied for different products in the Spanish Space Weather Service (SeNMEs) website <a href="http://www.senmes.es/index-en.php"target="_blank">http://www.senmes.es/index-en.php</a>.