Atomic layer deposition (ALD) was used to develop hydrophobic and water-repellent glass fiber cloths for operation in high temperatures up to 200°C. The cloths were deposited with highly conformal, pinhole-free, and uniform Al₂O₃ films with a thickness at 200 nm. The characteristics of the deposited films were studied using a scanning electron microscope. While the uncoated cloth was hydrophilic with an equilibrium contact angle around 40°, the ALD-coated cloth became hydrophobic with an equilibrium contact angle around 125°. Such a hydrophobicity resulted in an excellent water repellant characteristic, as such, while non-coated cloth absorbed the water immediately, the ALD-coated cloth showed a resistance against water transport into the nanoscale-coated fiber cloth for over 10 hours. This characteristic was maintained in the ALD-coated cloth after thermal cycling processes by heating the coated cloth up to 200°C for one hour. The present study would open a new research direction to leverage ALD for developing water-repellent glass fiber cloths in high-temperature applications, such as those for developing high-temperature wire insulations.