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Reading a Station NOAA-Style Monthly Climate Summary

How to read a station-generated NOAA-style monthly climate HTML: daily max, min, and precipitation, without treating it as official NCEI climate.

Back to Historical weather observations and forecasts

A monthly climatological summary that looks like a NOAA form is still a station product if a personal logger wrote it. The layout—one row per day, columns for mean temperature, maximum and minimum with times, degree days, rain, and wind—is a reading aid. It is not an NCEI archive and not an NWS Climatological Report (CLI or CLM). The useful skill is to read monthly max, min, and precipitation as the station defined them, with units and missing days in view.

The historical TNET Weather URL /parse_noaa.php rendered that HTML for a Mesa, Arizona Weather Display station. A recovered capture is a July 2007 monthly summary. That month is a historical example of the form. It is not the current climate of Mesa, and the daily rows are not copied here.

Historical context

Weather Display and similar programs can emit a file often named like dailynoaareport.htm: a fixed-width-looking monthly table under a heading such as “MONTHLY CLIMATOLOGICAL SUMMARY.” PHP on the historical site parsed or restyled that file for the web. The recovered July 2007 header named the station, printed elevation and latitude/longitude, and stated units: temperature in °F, rain in inches, wind in mph.

Those header facts are how you start a reading. They are not a reason to treat the table as official climate. The notebook at /nb-0005.php explains how to parse the file into a table without changing numbers. This page explains how to read the monthly summary as climate evidence—what each column means, and what it must not be used for.

Three products that share the word “NOAA”

Keep these separate while you read:

  1. NWS Climatological Report (Daily) CLI and (Monthly) CLM. Official text products for designated climate sites, issued on a defined schedule, with observed values, records, normals, and departures (NWS Instruction 10-104).
  2. NCEI station archives and U.S. Climate Normals. The long-term record and the 30-year normals (1991–2020 as of 2026) used for official departures (NCEI Climate Normals).
  3. Station “NOAA” HTML. Daily statistics from this personal station, laid out to resemble a classic monthly summary. Useful for the operator. Not (1) or (2).

If the page title or filename says NOAA, a visible sentence should still say: computed from the local station, not from NOAA/NCEI.

How to read monthly maximum, minimum, and precipitation

The month. Civil month in the station’s local calendar. The recovered example is July 2007. An incomplete month—published on the 6th, or after a logger gap—must not be read as a closed monthly climate. Trailing blank days are not zeros.

Mean temperature (daily). Often the average of that day’s maximum and minimum as the logger defines them, not a 24-hour integral unless the software is set that way. A desert station with a large diurnal range is where that choice shows.

High and low, with times. Extremes inside the logger’s day boundary (commonly midnight–midnight local). Time-of-extreme is only as good as the archive interval. A two-minute log cannot honestly claim a one-second peak.

Monthly maximum temperature is the highest daily high in the table among valid days. Monthly minimum is the lowest daily low among valid days. If any day is missing, say so. Official CLM practice is stricter: missing daily values can force the monthly value to missing (MM). A PWS table that still prints a monthly high after a three-day outage is a station statistic, not a CLM.

Rain (daily). Depth for that civil day in the header unit. A storm that crosses midnight splits across rows. Monthly precipitation is the sum of valid daily totals, not the sum of blanks treated as 0.00. Trace, if the file uses T, is wetter than missing and drier than 0.01 in in ordinary U.S. practice; it is not 0.00 and not 0.01.

Heating and cooling degree days. Derived indices against a base (commonly 65°F in U.S. practice). They are not observed temperatures. Changing the base changes the column. Monthly HDD/CDD are sums of daily values; missing days bias the month.

Wind. Average speed, high speed, time of high, and dominant direction. Dominant direction summarizes the day’s direction distribution. It is not automatically the direction at the time of the high gust. Units must match the header (mph in the 2007 Mesa file).

Departure from normal. Official CLI/CLM products include departures when a normals set exists for that climate site. A backyard HTML file usually omits true departures because the PWS has no NCEI normal. If a template prints a departure anyway, demand the normals station and period. Otherwise the column is invented.

Reading July 2007 as history, not as Mesa now

Use the recovered July 2007 summary only as a dated illustration of the form.

The header located a Mesa station and declared English units. The body, in the fragment that survived, listed early-July daily lines with hot afternoon maxima and warm nights—typical of a low-desert July at that station in that year, not a 2026 climate normal and not Phoenix Sky Harbor. Do not promote those rows into a city climate narrative. Do not update them. If you need the official climate of the Phoenix area, use NCEI and NWS CLI/CLM for the designated site.

Elevation and coordinates in a WD header are claimed siting, not a surveyed monument. They still belong in the reading: they are the station’s own metadata at the time of the file.

What the monthly form is for

Read it to answer station questions:

  • What were this logger’s hottest and coldest days in the named month?
  • How much rain did this gauge catch, and on which civil days?
  • Were degree days accumulated, and against which base?
  • How complete was the month (valid-day count)?

Do not read it to answer official questions:

  • What is the climate of Mesa or Phoenix?
  • Did the city set a record?
  • What is the departure from 1991–2020 normal?

Those questions require the official series. Different instruments, exposure, and quality control are expected. Do not “correct” the PWS toward CLI.

Distinct from neighboring URLs

/nb-0005.php is the parser’s problem: how to turn WD NOAA-format HTML into a structured table without restyling the numbers. This page is the climatologist’s problem: how to interpret the monthly summary once it is on screen.

/parse_noaa_date.php is archive navigation: choosing which date or month to load. This URL is the default monthly view.

/tws-dailynoaa.php is the verbose month of daily rows—an appendix with extra fields. This URL is the compact NOAA-like grid.

/weather/weekrep.htm is a seven-day or short-period extract, not a 28–31 day month.

Practical checklist

  1. Read the header first: station name, month, units, coordinates if present.
  2. Count valid days before trusting a monthly max, min, or rain total.
  3. Treat blank end-of-month rows as not-yet-observed, not as dry or as 0°F.
  4. Label HDD/CDD as derived.
  5. Do not title the page as NCEI or NWS CLI.
  6. If you add departures, name the normals source and keep them in a separate column.
  7. Treat July 2007 Mesa rows as historical station HTML, not as current climate.

For life-safety weather, use National Weather Service products. A station monthly table is not a warning.

Modern relevance

Monthly station summaries remain the operator’s climate diary. They become research evidence only with provenance: station HTML, not NCEI, with units, valid-day count, and a date. That is the same distinction TNET draws in data sources, quality controls, and methodology.

Observation hub: /legacy/observations/.

Sources