A wireless device comprising: global navigation satellite service (GNSS) positioning circuitry; and time measurement circuitry coupled to the GNSS positioning circuitry, the time measurement circuitry configured to: retrieve predicted positioning data and predicted orbital data from the GNSS positioning circuitry in response to a request for device time; retrieve long term learning data for a temperature sensing crystal of the time measurement circuitry, the LTL data including S-curve characteristics of the TSX and time tracking uncertainty of the TSX; and while the GNSS positioning circuitry is powered off: generate a GNSS-based device time estimate using the predicted positioning data and the predicted orbital data; update the GNSS-based device time estimate using a clock signal of the TSX to generate a final device time estimate, the update based on the retrieved LTL data for the TSX; detect a change in temperature of the wireless device; determine a time offset corresponding to the change in temperature based on the S-curve characteristics of the TSX; generate the final device time estimate further based on the determined time offset; output the final device time estimate in response to the request; update the time tracking uncertainty of the TSX based on the detected change in temperature; and periodically update the final device time estimate using a subsequent clock signal of the TSX and the time tracking uncertainty as long as the time tracking uncertainty of the TSX is below a threshold. global navigation satellite service (GNSS) positioning circuitry; and time measurement circuitry coupled to the GNSS positioning circuitry, the time measurement circuitry configured to: retrieve predicted positioning data and predicted orbital data from the GNSS positioning circuitry in response to a request for device time; retrieve long term learning data for a temperature sensing crystal of the time measurement circuitry, the LTL data including S-curve characteristics of the TSX and time tracking uncertainty of the TSX; and while the GNSS positioning circuitry is powered off: generate a GNSS-based device time estimate using the predicted positioning data and the predicted orbital data; update the GNSS-based device time estimate using a clock signal of the TSX to generate a final device time estimate, the update based on the retrieved LTL data for the TSX; detect a change in temperature of the wireless device; determine a time offset corresponding to the change in temperature based on the S-curve characteristics of the TSX; generate the final device time estimate further based on the determined time offset; output the final device time estimate in response to the request; update the time tracking uncertainty of the TSX based on the detected change in temperature; and periodically update the final device time estimate using a subsequent clock signal of the TSX and the time tracking uncertainty as long as the time tracking uncertainty of the TSX is below a threshold. retrieve predicted positioning data and predicted orbital data from the GNSS positioning circuitry in response to a request for device time; retrieve long term learning data for a temperature sensing crystal of the time measurement circuitry, the LTL data including S-curve characteristics of the TSX and time tracking uncertainty of the TSX; and while the GNSS positioning circuitry is powered off: generate a GNSS-based device time estimate using the predicted positioning data and the predicted orbital data; update the GNSS-based device time estimate using a clock signal of the TSX to generate a final device time estimate, the update based on the retrieved LTL data for the TSX; detect a change in temperature of the wireless device; determine a time offset corresponding to the change in temperature based on the S-curve characteristics of the TSX; generate the final device time estimate further based on the determined time offset; output the final device time estimate in response to the request; update the time tracking uncertainty of the TSX based on the detected change in temperature; and periodically update the final device time estimate using a subsequent clock signal of the TSX and the time tracking uncertainty as long as the time tracking uncertainty of the TSX is below a threshold. generate a GNSS-based device time estimate using the predicted positioning data and the predicted orbital data; update the GNSS-based device time estimate using a clock signal of the TSX to generate a final device time estimate, the update based on the retrieved LTL data for the TSX; detect a change in temperature of the wireless device; determine a time offset corresponding to the change in temperature based on the S-curve characteristics of the TSX; generate the final device time estimate further based on the determined time offset; output the final device time estimate in response to the request; update the time tracking uncertainty of the TSX based on the detected change in temperature; and periodically update the final device time estimate using a subsequent clock signal of the TSX and the time tracking uncertainty as long as the time tracking uncertainty of the TSX is below a threshold.