How Meteorology Expert Witnesses Get Excluded Under Daubert — and How to Survive the Cross

Daubert is not a medicine problem. Under Kumho Tire and the 2023 amendment to Federal Rule of Evidence 702, the trial court's gatekeeping applies to every form of specialized testimony — meteorology included. A 20-year study of 2,842 challenges to non-medical experts found that roughly half of those opinions were excluded or partially excluded, and the single most-cited reason was “unreliable methodology.”

The exclusion rarely happens in a written motion alone. It is built, piece by piece, in the deposition cross-examination — where opposing counsel walks a meteorology expert into conceding scope, methodology, or an assumption that unravels the whole opinion. Here are the three traps, and how a prepared expert answers each one.

The three ways meteorology experts lose ground

Scope: testifying outside your lane

The cross-examiner's question sounds simple:

You opine it was icy at the scene — but the nearest weather station was miles away, correct?

Why it works: Station-distance interpolation. Disclose the distance and the method bridging it.

A stronger answer: “I used the nearest stations, radar, and accepted interpolation methodology and disclosed the station distance and its effect on the certainty of the conclusion.”

Methodology: the reliability attack

The cross-examiner's question sounds simple:

Your reconstruction relied on hourly observations — conditions can change between them, can't they?

Why it works: Temporal resolution. State the observation interval and how you bridged it.

A stronger answer: “I noted the temporal resolution of the observations and used radar and other data to assess conditions between them.”

Assumptions: the one premise that sinks the opinion

The cross-examiner's question sounds simple:

You assume the parking lot matched the regional data — but local conditions vary, don't they?

Why it works: The microclimate assumption. Address local variation or flag it.

A stronger answer: “I addressed micro-scale variation where the data allowed and flagged the limits of extrapolating regional data to the specific site.”

How to prepare for the cross before you're sworn in

Every one of those traps is defeatable — but not by reading your report one more time. The experts who survive the cross have done three things:

• Rehearsed the cross-examination out loud, repeatedly, against a realistic examiner — so the scope concession, the methodology defense, and the assumption hedge are second nature.
• Mastered the record, so that when counsel asks them to recall the one line buried in thousands of pages of the weather data, radar, and station records, they can produce it in seconds rather than fumble.
• Stress-tested the report against FRE 702 — finding the reliability gaps before opposing counsel does.

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