# Ai2 — HiRO-ACEv2: Simulating extreme weather at 3 km resolution for a fraction of the cost

- Company: Ai2 (allenai.org)
- Announced: 2026-10-14
- Category: model-update
- Coverage: not counted
- Announcement: yes
- Group: models
- Source: https://allenai.org/blog/hiro-acev2
- Record: https://forck.live/items/22275-hiro-acev2-simulating-extreme-weather-at-3-km-resolution-for-a-fraction-of-the
- Subject: Olmo / Molmo / Asta
- Models affected: HiRO-ACEv2, HiROv2, ACE

Ai2 released HiRO-ACEv2, an update to its climate emulator system. The new HiROv2 downscaling model predicts multiple high-resolution fields (rain, wind, pressure) simultaneously and improves accuracy for extreme events, matching X-SHiELD's high-resolution statistics to within 3% for events occurring once per million data points. The full system generates global 3 km climate data at roughly 1/300th the cost of X-SHiELD, and a web demo and downloadable models are available.

## Evidence

Verbatim from https://allenai.org/blog/hiro-acev2:

> HiROv2 can reproduce even extremely rare rain, wind, and pressure events with high accuracy, while the full system can generate global 3 km climate data at about 1/300th the cost of X-SHiELD, a high-resolution global atmospheric model that explicitly simulates storms and other small-scale weather.

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