Filling out the header
 Image of the top portion of the B-91 Form


** NOTE: You DO NOT  need to fill out any box with the word "River" in it.  This box is reserved for those locations that read river gauges. Hardly any COOP Observers in the country do this anymore due to safety reasons. This task has instead been delegated to official river authorities who maintain the river gauge. **

There are only 8 boxes you need to fill out:
  • Box 1: Fill in your station name.
  • Box 2: Fill in the month either by name or number.
  • Box 3: Fill in the year.
  • Box 4: Fill in the State by name or abbreviation.
  • Box 5: Fill in the county the weather equipment is located in.
  • Boxes 6&7: These boxes are for filling in the time that you take your observation. If you take temperature readings, put the time of your observation in Box 6 (usually 7 or 8 am). If you take precipitation measurements, put the time of your observation in Box 7 (usually 7 or 8 am). If you take both temperature readings and precipitation readings, put a time in Boxes 6 and 7.
  • Box 8: Fill in the time zone: "Central". If you wish to put "Central Daylight (CDT)" or "Central Standard (CST)", you may. Note: CDT refers to the timeframe of early spring through mid fall and CST refers to the mid fall through winter timeframe.
Filling out the bottom
 Image of the bottom portion of the B-91 Form
There are 3 boxes you need to fill out:
  • Box 9 : Please sign your name in this box.
  • Box 10 &11: These boxes should already be filled out for you (via a stamp or a sticker). If they are not� Box 10 is our office here in Fort Worth .  You can fill in "WFO FWD" which is short hand for "Weather Forecast Office Fort Worth". Box 11 is your 7 number ID that has two dashes in it. The numbers all begin with "41-". The prefix "41-" refers to Texas .
  • Remember to fill in your data on the row for the date you take your reading!!  If you read the temperature and precipitation on the 16th of the month, write the values on the row for the 16th.  DO NOT write your values on the day before (or the day after), even though the high temperature reading may have been on the previous day and/or it rained on the previous day (the 15th of the month in this example).  NCDC has a way of accounting for the day and time difference, so make sure you are writing your readings on the actual day that you take them!
  • If you took your observation at a time other than your official time�indicate this by filling in the "Time of observation if different from above" column with the time you took your reading(s) at. For example, if your official reporting time is 8 am and you took your reading on the 15th at 9 am, write "9:00" in the "Time of observation if different from above" column on the row for the 15th of the month.
  • Regarding temperature readings taken at 7 or 8 am... The rule of thumb for temperature reporting is that the high temperature must be equal to or higher than the "At Ob" temperature recorded that day and the previous day; and the low temperature must be equal to or lower than the "At Ob" temperature recorded that day and the previous day. For example, you take your temperature readings on the 16th and the "At Ob" temperature is 74.  The previous day (the 15th), your "At Ob" temperature was 72. Therefore, for your temperature readings that you take on the 16th, your max temperature must be equal to or higher than 74 (the higher of the two "At Ob" temperature readings) and your min temperature must be equal to or lower than 72 (the lower of the two "At Ob" temperature readings).
  • Please remember to fill in a value for every day of the month! If there was no precipitation on a certain day, please record "0.00" precipitation. If a zero ("0.00") value is not filled in, the data could be assumed to be missing. By filling in a value for every day, you define in your permanent records the days precipitation was recorded and the days no precipitation fell.
  • Precipitation is recorded to the nearest hundredth of an inch (two decimal places; i.e.: 0.05, 1.70, 11.06). Please make sure each entry has two decimal places and please place the decimal in the correct location. (Snowfall is recorded the nearest tenth of an inch. See "How to Measure and Record Snow" for additional information and instructions).
  • Record a Trace of precipitation with a "T". A trace is defined as a measurement less than 1/100 of an inch. You may also record a trace of precipitation when it briefly rains at your location but doesn't hit the rain gauge, or if it sprinkles for a short time, but not enough to measure 0.01".
  • Add up your total precipitation at the end of each month and enter the total at the bottom of the "Rain, melted snow, etc" column; next to the box marked "Sum". If you have missing days on your report, do not enter a total.
  • Be careful when recording precipitation on foggy or hazy mornings.  Oftentimes, dew will form on the plastic funnel that then drops into the rain gauge (plastic inner tube) . Your rain gauge may record 0.01" inches or more, but this is false and should not be recorded!
  • Please go back and fill in any missing days before you send in your report at the end of the month. If you don't have data for a certain day(s), please fill in an "M" to indicate missing data.
  • You can enhance your weather report by filling in the "Weather" column when the listed weather elements occur. Just place an "X" in the "Weather" column for the type of weather. You can also make comments in the "Remarks" section about the weather (i.e. hail size, thunderstorm wind damage). Mark these X's and comments on the day that the weather event actually occurs!  This is one of the few times that you will actually mark the event on the day it occurred!
  • You can also enhance your weather report by marking the time(s) of precipitation as it occurs. Mark these times on the actual day that it rains/snows! A straight line indicates that you know for sure when it rained/snowed. A squiggly line indicates you are unsure of exactly when it rained or snowed, but you have a best guess of when it happened. is the U.S. government's official web portal to all federal, state and local government web resources and services.