SOURCES & METHODOLOGY
Trust the number—or see why it is missing.
Canadian and Mexican locations
Canadian coordinate-based pages use official station observations and regional forecasts from Environment and Climate Change Canada. Daily reporting windows follow the station’s observation day. Hourly totals include only completed, non-overlapping hours; incomplete coverage remains unavailable. Where a station reports total precipitation rather than rain separately, the page labels it as precipitation, which includes the water equivalent of snow. Contains information licensed under the Environment and Climate Change Canada Data Services End-use Licence.
Mexican coordinate-based pages use Open-Meteo rainfall estimates and forecasts through its commercial service. These are model estimates rather than measurements at the location. Rain and showers are included; snowfall is excluded. Today sums completed hours since local midnight and excludes future forecast rainfall. Daily history uses historical model data, supplemented by recent archived forecast estimates while the historical data updates. All estimates retain their labels. Monthly and yearly totals require complete daily coverage, with missing data never counted as zero. Data are provided under CC BY 4.0.
Observed measurements
Completed daily rainfall, snowfall, and snow-depth values come from NOAA National Centers for Environmental Information daily summaries. Each ZIP uses a nearby station with recent records; its name and identifier are shown so you can see where the measurement came from.
Monthly and yearly rainfall
Month-to-date, last-month, and year-to-date rainfall totals use official records from the NOAA Regional Climate Centers’ Applied Climate Information System (ACIS) and NOAA/NCEI daily summaries. The app checks stations in distance bands up to 125 miles, including stations across state lines. For each period, it chooses the nearest checked station with no missing days and current complete coverage. A closer complete NOAA daily record takes priority over a farther ACIS record. The station, distance, and coverage date appear with the total. A verified result is shared for up to one day; incomplete totals remain unavailable rather than being presented as final.
Today so far
Rainfall “today so far” is normally a preliminary accumulation from hourly National Weather Service observations. If the local gauge reports that its precipitation amount is unavailable, the app uses a clearly labeled NOAA/NWS MRMS radar estimate for the shortest available period covering the local day. That estimate can include a few hours from the prior day and is replaced by the completed NOAA daily report when it arrives. Nationally consistent live snowfall accumulation is not available because many official snowfall observations are measured manually, so snowfall shows the latest completed official report and its date.
On-demand daily rainfall
When a location is opened, the app requests up to 72 hours of raw NWS/METAR observations and reconstructs recent station-day rainfall from the reported hourly amounts. Overlapping reports are deduplicated. Preliminary and partial results for visited locations are retained only on that device, then replaced by the completed NOAA daily value when it arrives. A zero appears only when the available reporting supports zero; missing coverage remains pending.
Snow-event totals
A snow event combines consecutive reporting days with measurable new snowfall at the selected NOAA station. An event remains preliminary while snowfall is current, then becomes a final calculated event total. Snowfall, snow depth, and liquid equivalent remain separate measurements.
Forecasts
Short-term precipitation probability comes from the public National Weather Service API. Forecast values appear only under “What may fall.” They are never added to measured totals.
Local drought status
The LocalRainfall view matches the reporting station’s coordinates to the latest weekly U.S. Drought Monitor map and shows one local classification from Normal through D4. The classification describes the surrounding area, not the individual rain gauge.
Nearby reporting stations
The Explore Nearby section lists the latest available daily reports from Regional Climate Centers / ACIS stations within 50 miles, closest first. Two stations appear initially; “Show more stations” reveals the rest. Daily reports can cover different observation periods. Precipitation includes the water equivalent of snow; dates, distances, and sources are available in each station’s details.
Why nearby readings vary
Rain and snow can vary over short distances. Nearby NWS stations are listed as context, but measurements from different stations are not mixed into a single monthly or yearly rainfall total. Each period keeps its nearest checked station with complete coverage, rather than moving a closer total farther away to make station names match. A notice identifies totals from different stations, and stations more than 25 miles away are marked “Farther station.” A regional station reading may differ from rainfall at the selected ZIP code.
Missing and delayed data
NOAA daily summaries often post the next morning and can arrive a day or two later. Government responses are cached only briefly by the application; recent visited station-days and offline results are saved on the user’s device. A missing measurement remains missing; it is never converted to 0.00 inches. Cached results are time-stamped, and offline results are labeled.
Snow-season convention
A snow season runs from November 15 through April 15, inclusive. It is labeled by the year in which November 15 occurs. For example, the 2025–26 season begins November 15, 2025 and ends April 15, 2026.