Measurements · Meteorology
Precipitation Intensity
Also known as rain rate, rainfall intensity, rainfall
Instantaneous precipitation (rain) rate.
What it is
What is precipitation intensity?
Precipitation intensity is the rate at which precipitation falls, reported as a depth per unit time: millimeters per hour (mm/h). Where a rainfall total tells you how much water arrived, intensity tells you how fast, and the two can be very different: 10 mm delivered evenly over a day is a soaking drizzle, while the same 10 mm in ten minutes is a damaging cloudburst. Intensity is inherently short-term and highly variable, rising and falling through a storm, so it is characterized by its peak short-duration rates as much as by any average.
Health and operational effects
Intensity, not total, drives the most acute hazards. Flash flooding, surface-water ponding, drain and culvert surcharge, soil erosion, and landslides are all governed by how fast water arrives relative to how fast the ground and drainage can absorb or convey it. A high-intensity burst overwhelms systems that would comfortably handle the same volume spread over several hours.
Operationally, intensity thresholds trigger real-time responses: pausing high-risk work, activating pumps and flood defenses, closing roads, and managing runoff and erosion controls on construction and contaminated sites. It is also central to drainage and stormwater design, where systems are sized against intensity for a chosen storm duration and return period rather than against annual totals.
How it is measured
How Precipitation Intensity Is Measured
Intensity is derived from the same instruments that measure accumulation, from the timing of their output. A tipping-bucket rain gauge yields intensity from the interval between tips (each tip is a fixed depth, so closely spaced tips mean high intensity), though its resolution falls at very low rates and it can under-catch in intense downpours. Optical disdrometers measure the size and fall speed of individual drops as they cross a laser sheet to compute an instantaneous rate and drop-size distribution. With fast response and no moving parts, they suit high-resolution intensity work. Weighing gauges and radar-based sensors also provide rate. The shorter the integration time, the more faithfully brief, damaging peaks are captured.
An instrument on Thiamis3
A third-party instrument connected to a Thiamis gateway, reporting into the same Environet account.
Placing precipitation intensity sensors
Intensity is measured by the same gauges as accumulation and follows the same siting rules: an open, level position clear of obstructions by at least twice their height, away from the wind eddies and shelter that distort catch. Because intensity is a short-duration quantity, wind-induced under-catch and gauge resolution matter even more than for totals: a coarse tipping-bucket resolution smears out brief peaks. Where fine intensity detail is required, an optical disdrometer sited with a clear sample volume gives higher time resolution than a mechanical gauge.
Every device and option that measures Precipitation Intensity 3
| Device / option | Type | Base platform | Measures |
|---|---|---|---|
 Airmar · 110WX, 110WXS, 120WX… | Weather Stations | Thiamis | Precipitation IntensityAbsolute HumidityDew PointHeat IndexRelative HumidityPrecipitationBarometric Pressure |
 Davis · Davis Wizard III, Davis Wizard II, Davis Monitor… | Weather Stations | Thiamis | Precipitation IntensityDew PointHeat IndexRelative HumidityLeaf TemperatureLeaf WetnessPrecipitation |
 Lufft · WS100, WS200, WS300… | Weather Stations | Thiamis |
Where it is monitored
Solutions That Monitor Precipitation Intensity
Each one links to the solution page showing what that industry measures it for.
Hydrology, Level & Flow
Often addedFlood warning, stream gauging, and groundwater
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Questions
Precipitation Intensity FAQ
What is the difference between rainfall intensity and total rainfall?
Total rainfall is the accumulated depth over a period, in millimeters; intensity is how fast it is falling at a moment, in millimeters per hour. A modest total delivered as an intense burst can cause flooding, while a large total spread over days may pass without incident, so the two describe different risks.
Why does rainfall intensity cause flash flooding?
Flash floods happen when water arrives faster than the ground can absorb it and drains can carry it away, so it is the peak rate, not the eventual total, that overwhelms the system. Short, intense bursts over hard or saturated ground produce rapid runoff and sudden rises in streams and drains.
How is precipitation intensity measured?
It is calculated from the timing of a rain gauge's output (the spacing of tips in a tipping-bucket gauge, or a continuous rate from a weighing gauge) or measured directly by an optical disdrometer that senses individual drops. Finer time resolution captures brief, damaging peaks that a coarse gauge would average away.
How do I monitor precipitation intensity?
Rain rate is measured with an external gauge rather than the built-in Aethair sensors, so pair a Thiamis gateway with a tipping-bucket gauge or optical disdrometer, choosing a fast integration time where peak rates matter. Use the configurator to combine precipitation intensity with rainfall totals and wind for storm and flood monitoring.
Monitor Precipitation Intensity on the Record
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