The lowest temperature recorded/measured during a specified time period.
Temperature and Dew Point
Observing Standards
The method of obtaining temperature and dew point varies according to the
system in use at the station. The data may be read directly from digital or
analog readouts, or calculated from other measured values.
- Temperature and Dew Point Sensor Range. The range for the temperature
and dew point sensors shall be determined by the responsible agency considering
the local climatology. See Table A-18.
| Table A-18. Temperature and Dew
Point Sensor Accuracy and Resolution (Co) |
| Parameter |
Range |
Accuracy |
Resolution |
| Temperature |
-62 to -50
-50 to +50
+50 to +54 |
+ or - 1.1
+ or - 0.6
+ or - 1.1 |
0.1
0.1
0.1 |
| Dew Point |
-34 to -24
-24 to -01
-01 to +30 |
+ or - 2.2
+ or - 1.7
+ or - 1.1 |
0.1
0.1
0.1 |
- Temperature. Temperature shall be determined to the nearest tenth of a
degree Celsius at all stations.
- Dew Point. At designated stations, dew point shall be determined to
the nearest tenth of a degree Celsius with respect to water at all temperatures.
- Maximum and Minimum Temperature. At designated stations, maximum and
minimum temperatures that occurred in the previous 6 hours shall be determined
to the nearest tenth of a degree Celsius for the 0000, 0600, 1200, and 1800 UTC
observations. The maximum and minimum temperatures for the previous 24 hours
shall be determined to the nearest tenth of a degree Celsius for the 0000 LST
observation.
Temperature and Dew Point
Reporting Standards
- Resolution for Temperature and Dew Point. The reporting resolution
for the temperature and the dew point in the body of the report shall be whole
degrees Celsius. The reporting resolution for the temperature and dew point in
the remarks section of the report shall be to the nearest tenth of a degree
Celsius. Dew point shall be calculated with respect to water at all temperatures.
- Maximum and Minimum Temperatures. At designated stations, maximum and
minimum temperatures shall be reported as additive data in the 0000, 0600, 1200,
and 1800 UTC and 0000 LST observations.
- Reporting Procedures. Temperature and dew point are reported in the
body of the report. Temperature and dew point in the remarks section shall
only be reported in METARs. Maximum and minimum temperatures shall be
reported in the remarks section of the METAR.
Table A-19 is a summary of the temperature and dew point observing and
reporting standards.
| Table A-19. Summary of Temperature
and Dew Point Observing and Reporting Standards |
| Parameter |
Section of Report |
| Body of METAR & SPECI |
Remarks of METAR |
| Temperature |
Reported in whole degrees Celsius at all
stations. |
Reported to tenths of degrees Celsius at
designated stations. |
| Dew Point |
Reported in whole degrees Celsius at all
stations. |
Reported to tenths of degrees Celsius at
Designated stations. |
| Maximum and Minimum Temperature |
Not reported |
Designated stations report at 0000, 0600, 1200,
and 1800 UTC. |
| 24-Hour Maximum and Minimum Temperatures |
Not reported |
Designated stations report at 0000 LST |
Coding and Decoding the
Temperature/Dew Point Group (T'T'/T'dT'd)
The temperature shall be separated from the dew point with a solidus
"/". The temperature and dew point shall be coded as two digits
rounded to the nearest whole degree Celsius. For example, a temperature of
0.3oC would be coded as "00". Sub-zero temperatures and
dew points shall be prefixed with an M. For example, a temperature
of 4oC with a dew point of -2oC would be coded as
"04/M02"; a temperature of -0.5oC would be coded as
"M00".
If the temperature is not available, the entire temperature/dew point group
shall not be coded. If the dew point is not available, the temperature shall
be coded followed by a solidus "/" and no entry made for dew point. For
example, a temperature of 1.5oC and a missing dew point would be
coded as "02/".
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