A system for determining a reliability line rating for a transmission line during a present interval, the system comprising: a reliability determination module; and a line monitor on a transmission line, the line monitor comprising: a clearance sensor to determine a line clearance measurement; a line temperature sensor to determine a line temperature measurement; and a transmitter to transmit the line clearance measurement and the line temperature measurement to the reliability determination module disposed on a remote utility server, the reliability determination module being configured to, in response to the line clearance measurement and the line temperature measurement, generate a temperature-clearance model for the transmission line based on the received line clearance measurement and line temperature measurement, characterized in that the line monitor further comprises a line current sensor to determine a line electrical load, and in that the reliability determination module is further configured to: generate a plurality of past dynamic line ratings based on a maximum line temperature for the transmission line, wherein the maximum line temperature is determined by comparing a minimum acceptable clearance for the transmission line to the temperature-clearance model; determine a scaling factor based on the plurality of past dynamic line ratings; generate a present dynamic line rating at a start of a present interval; and scale the present dynamic line rating in response to the scaling factor to obtain a reliability line rating for the present interval. a reliability determination module; and a line monitor on a transmission line, the line monitor comprising: a clearance sensor to determine a line clearance measurement; a line temperature sensor to determine a line temperature measurement; and a transmitter to transmit the line clearance measurement and the line temperature measurement to the reliability determination module disposed on a remote utility server, the reliability determination module being configured to, in response to the line clearance measurement and the line temperature measurement, generate a temperature-clearance model for the transmission line based on the received line clearance measurement and line temperature measurement, characterized in that the line monitor further comprises a line current sensor to determine a line electrical load, and in that the reliability determination module is further configured to: generate a plurality of past dynamic line ratings based on a maximum line temperature for the transmission line, wherein the maximum line temperature is determined by comparing a minimum acceptable clearance for the transmission line to the temperature-clearance model; determine a scaling factor based on the plurality of past dynamic line ratings; generate a present dynamic line rating at a start of a present interval; and scale the present dynamic line rating in response to the scaling factor to obtain a reliability line rating for the present interval. a clearance sensor to determine a line clearance measurement; a line temperature sensor to determine a line temperature measurement; and a transmitter to transmit the line clearance measurement and the line temperature measurement to the reliability determination module disposed on a remote utility server, the reliability determination module being configured to, in response to the line clearance measurement and the line temperature measurement, generate a temperature-clearance model for the transmission line based on the received line clearance measurement and line temperature measurement, generate a plurality of past dynamic line ratings based on a maximum line temperature for the transmission line, wherein the maximum line temperature is determined by comparing a minimum acceptable clearance for the transmission line to the temperature-clearance model; determine a scaling factor based on the plurality of past dynamic line ratings; generate a present dynamic line rating at a start of a present interval; and scale the present dynamic line rating in response to the scaling factor to obtain a reliability line rating for the present interval.