Altona climate

Altona Weather in September

NOAA 1991-2020 normals for Boulder, 15.9 km from Altona

Average highs run from 84°F on September 1 to 73°F on September 30, and lows from 53°F to 43°F. Normal precipitation for the month is 2.09 in over about 8 wet days.

September day by day

The normal high and low for each date, and the record, in °F.

Normal daily high and low temperature at Altona, in °F, with the record for each date.020406080100120151015202530
  • Normal low
  • Normal high
  • Record high
  • Record low

September at a glance

Average high
79°F
Average low
48°F
Precipitation
2.09 in
Snowfall
1.0 in
Record high
101°FSep 6, 2020
Record low
18°FSep 30, 1985
Chance of a freeze
31%
Days of 90°F or more
2.7
Daylight
13 h 03 min to 11 h 48 min
Cloud cover
54%
Humidity
51%
Dew point
31°F
Wind
5.8 mph

Every day of the month

A wet day has at least 0.01 inch of precipitation; snow means at least 0.1 inch of snowfall.

DateNormal highNormal lowRecord highRecord lowChance wetChance of snow
Sep 184°F53°F99°F 196038°F 195029%1%
Sep 283°F52°F100°F 199536°F 195229%1%
Sep 383°F52°F99°F 201934°F 193428%1%
Sep 483°F52°F100°F 199537°F 192128%1%
Sep 583°F52°F98°F 199835°F 191828%1%
Sep 682°F51°F101°F 202036°F 192128%1%
Sep 782°F51°F96°F 198236°F 192228%1%
Sep 882°F51°F96°F 198828°F 192928%1%
Sep 982°F51°F98°F 202231°F 194128%1%
Sep 1081°F50°F96°F 197930°F 196227%1%
Sep 1181°F50°F96°F 199431°F 191627%1%
Sep 1281°F50°F98°F 193932°F 191227%1%
Sep 1380°F49°F96°F 189530°F 199327%1%
Sep 1480°F49°F97°F 199027°F 199327%1%
Sep 1579°F49°F94°F 195628°F 199326%2%
Sep 1679°F48°F95°F 189532°F 195126%2%
Sep 1779°F48°F98°F 200029°F 196526%2%
Sep 1878°F48°F98°F 189530°F 196526%2%
Sep 1978°F47°F94°F 199820°F 197126%2%
Sep 2077°F47°F92°F 198023°F 197125%2%
Sep 2177°F46°F93°F 194926°F 198325%2%
Sep 2276°F46°F91°F 191523°F 199525%2%
Sep 2376°F46°F90°F 194724°F 199525%2%
Sep 2476°F45°F91°F 199221°F 192625%2%
Sep 2575°F45°F90°F 199224°F 200025%2%
Sep 2675°F44°F91°F 194924°F 200024%2%
Sep 2774°F44°F92°F 200123°F 199624%2%
Sep 2874°F44°F92°F 195322°F 198424%3%
Sep 2973°F43°F92°F 199419°F 198524%3%
Sep 3073°F43°F92°F 199418°F 198524%3%

Chance of rain

The chance of at least 0.01 inch of precipitation on each date at Altona, in percent, and of at least 0.1 inch of snowfall.01020301102030
  • Chance of a wet day
  • Chance of snowfall

Sunrise and sunset

Times for 2026, local time (MDT).

September 1
sunrise 6:29 AM, sunset 7:32 PM
September 30
sunrise 6:57 AM, sunset 6:45 PM

Every day of September: sun and moon

Other months

Sources

Normals: NOAA NCEI U.S. Climate Normals, 1991-2020, station USC00050848 (Boulder), public domain. Records: NOAA GHCN-Daily, station USC00055116, every year on file, quality-flagged values removed. Cloud, humidity, wind and sunshine: NASA POWER (MERRA-2, CERES and GEWEX SRB), 1991-2020. The data was obtained from the National Aeronautics and Space Administration (NASA) Langley Research Center's Prediction Of Worldwide Energy Resources (POWER) project funded through the NASA Earth Science Division: POWER Daily API v2, accessed 2026-09-24. Sun and moon: computed with the NOAA solar equations and Meeus.