How much rain fell on your field?
NOAA radar and gauge estimate (MRMS), not a rain gauge reading.
Sigurd Lindquist, CCA
Where is the field?
Map: last 7 days around the spot
Each square is about 2.8 miles north to south and 2 miles across. Tap the map to read any square.
How close radar comes to a gauge
I checked the estimate against 1,175 NOAA co-op rain gauges in 47 states, every morning report from October 1 to 13, 2026 (14,476 gauge-days), using the same squares this page shows.
- On days with a tenth of an inch or more at the gauge or on radar (2,473 of them), radar and gauge were a median 0.13 in apart. Radar ran a little low: 0.03 in under on average.
- On days the gauge caught half an inch or more (1,032), the median miss was 0.21 in, or 20%, and radar read about 9% under the gauge.
- Added up over the 13 days, at the 623 gauges that reported every day and caught half an inch or more, the median gap was 0.20 in (13%).
- About 1 wet day in 17, radar showed a tenth or more where the gauge caught nothing, and about 1 in 15 the other way.
That is two weeks of fall rain. Summer thunderstorms are harder on radar, and I will run the check again in storm season. Your own gauge can differ from both: a storm can drop an inch on one side of a section and a quarter inch on the other.
How the numbers are worked
Source. NOAA’s Multi-Radar Multi-Sensor system (MRMS) blends every NWS radar with rain gauges that report each hour. This page uses its Pass 2 multi-sensor totals, the run that waits about an hour for more gauges to come in, from NOAA’s open data copy on AWS (noaa-mrms-pds). NOAA’s grid is about two-thirds of a mile; I average it 4 by 4 into squares of 0.04 degree (about 2.8 miles north to south and 2 miles across) and round to the hundredth of an inch.
Windows. All of them end at the newest hour NOAA has posted. Last 24 hours and last 3 days are NOAA’s own 24- and 72-hour totals. Last 7 days adds NOAA’s two most recent 72-hour totals and the 24 hours before them. This month runs from midnight Central on the 1st, built the same way from NOAA’s 72, 24, 12, 6, 3 and 1-hour totals. If any piece is missing, that window is left off rather than guessed.
Bad squares. MRMS has a few fixed bad cells (one near Mount Baker, Washington, read 95 inches for half of October 2026). A square of 2 inches or more that is 20 times the middle of the 24 squares around it shows as no data.
The gauge beside it. The county gauges are the NOAA co-op and CoCoRaHS stations on the county rain pages. Their days end at the morning reading, about 7 am, so the radar number beside them is NOAA’s 24-hour total ending 12:00 UTC (7 am Central daylight time), added over the same days. Airport stations close their day at midnight and are left out. Gauge reports come in about once a week.
Updates. About four times a day, an hour or so after NOAA posts the 0, 6, 12 and 18 UTC totals. If the newest total is more than 9 hours old, the page says so.
Questions
Where does this rain number come from?
From NOAA’s Multi-Radar Multi-Sensor system (MRMS), which blends the national radar network with rain gauges that report every hour. This page uses its Pass 2 multi-sensor totals, the gauge-corrected run, averaged into squares about 2.8 miles by 2 miles. It is an estimate for the square your field sits in, not a reading from a gauge.
How close is the radar estimate to a rain gauge?
Checked against 1,175 NOAA co-op gauges in 47 states from October 1 to 13, 2026, radar and gauge were a median 0.13 inch apart on days with a tenth of an inch or more. On days a gauge caught half an inch or more, the median miss was 0.21 inch (20%), and radar read about 9% under the gauge. Over the 13 days added up, the median gap was 0.20 inch (13%).
Why does my rain gauge read different from the radar?
A gauge catches rain in a few square inches; the radar number is an average over about five square miles. Radar sees rain above the ground, sometimes a mile up or more far from the radar, and wind, evaporation and hail all change what reaches the field. Gauges miss rain too, in wind and when they are read late. The two usually land close; on a heavy day expect a few tenths either way.
How often does it update?
About four times a day. NOAA posts its gauge-corrected totals about an hour after each hour ends, and the page reads the 0, 6, 12 and 18 UTC totals shortly after. The page shows the newest hour in your time zone and says so if the data is more than 9 hours old.
Does it count snow?
It counts melted water, so snow shows up as its water content. Radar is weaker with snow than with rain, so treat winter numbers loosely.
Can I check a field instead of my ZIP?
Yes. Open a field or a point on Field Scout and follow its rain link, or tap anywhere on the map here to read that square. The page covers the lower 48 states; NOAA’s radar rain grid does not cover Alaska or Hawaii.
Related
- Rain this year by county, from the gauge
- Hail map
- Field Scout
- Rain Print: a year of rain, printed
- Spray advisory
Sources: NOAA National Severe Storms Laboratory and NCEP, Multi-Radar Multi-Sensor (MRMS) MultiSensor_QPE 24H, 72H and shorter Pass 2 products, NOAA Open Data Dissemination (noaa-mrms-pds); NOAA co-op and CoCoRaHS daily reports via RCC-ACIS for the gauge comparison. Map: OpenStreetMap, CARTO.