We evaluate the feasibility of remote high-temperature thermometry based on the blackbody-radiation-induced AC Stark shift of Rydberg electromagnetically induced transparency (EIT) resonances in ${}^{87}\mathrm{Rb}$ vapor. Extending the Farley-Wing formalism to the 1000–4000 K range, we show that the BBR shift of Rydberg states converges to the state-independent ${\mathrm{T}}^2$ asymptotic for principal quantum numbers $\mathrm{n}>20$, with convergence accelerating at elevated temperatures. A geometric dilution model accounts for the finite solid angle subtended by a remote blackbody source, and a shutter-based differential protocol removes the ambient BBR baseline. For a reference geometry with a 5 cm aperture at 3 cm standoff (path-averaged dilution factor ${\eta }^0=0.24$), the measurable signal reaches 25 kHz at 2000 K and exceeds 100 kHz at 4000 K. Absolute-mode EIT spectroscopy yields a thermometric sensitivity of 26 Hz/K at 2000 K in an ideal transparent cell, while differential Rydberg-Rydberg measurements are 2 orders of magnitude less sensitive due to the universality of the asymptotic shift. The $5{\mathrm{S}}_{1/2}$ ground-state BBR correction to the two-photon signal, evaluated dynamically using relativistic all-order matrix elements, is negligible at room temperature but reaches 6.7% at 2000 K and 18.6% at 4000 K, exhibiting nonmonotonic behavior driven by the interplay of the thermal spectrum with the $5\mathrm{S}\to 5\mathrm{P}$ resonance. With comb-referenced spectroscopy, subkelvin temperature uncertainty is achievable at 2000 K within $\sim {10}^2$ s of averaging, paving a path toward SI-traceable remote high-temperature thermometry linked directly to the definition of the second.

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• Rydberg gases
• Stark effect
• Atomic gases
• Optical spectroscopy
• Resonance techniques
• Spectroscopy