Altona climate

Altona Weather in May

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

Average highs run from 66°F on May 1 to 77°F on May 31, and lows from 38°F to 47°F. Normal precipitation for the month is 3.21 in over about 13 wet days.

May 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

May at a glance

Average high
71°F
Average low
43°F
Precipitation
3.21 in
Snowfall
2.0 in
Record high
100°FMay 30, 2003
Record low
18°FMay 1, 1989
Chance of a freeze
73%
Days of 90°F or more
0.5
Daylight
13 h 55 min to 14 h 50 min
Cloud cover
70%
Humidity
59%
Dew point
28°F
Wind
6.7 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
May 166°F38°F92°F 199218°F 198937%9%
May 266°F38°F90°F 202124°F 195437%9%
May 367°F39°F87°F 194024°F 198838%8%
May 467°F39°F89°F 193627°F 194438%8%
May 567°F39°F94°F 200018°F 191738%7%
May 667°F40°F94°F 200024°F 199938%7%
May 768°F40°F89°F 200424°F 197839%7%
May 868°F40°F93°F 189524°F 197839%6%
May 969°F41°F93°F 191624°F 200239%6%
May 1069°F41°F90°F 196227°F 200239%5%
May 1169°F41°F90°F 196224°F 194639%5%
May 1270°F42°F91°F 196225°F 199940%5%
May 1370°F42°F92°F 196222°F 191240%4%
May 1470°F42°F92°F 202627°F 192440%4%
May 1571°F43°F92°F 199628°F 192240%4%
May 1671°F43°F93°F 192731°F 189540%4%
May 1772°F43°F96°F 199628°F 191040%3%
May 1872°F43°F90°F 189726°F 191540%3%
May 1972°F44°F94°F 199630°F 191540%3%
May 2073°F44°F95°F 192530°F 193140%3%
May 2173°F44°F95°F 192525°F 200140%3%
May 2274°F45°F91°F 196429°F 200140%2%
May 2374°F45°F92°F 196432°F 200240%2%
May 2474°F45°F95°F 189628°F 200240%2%
May 2575°F46°F91°F 196733°F 194640%2%
May 2675°F46°F90°F 192032°F 195040%2%
May 2776°F46°F93°F 189532°F 195040%1%
May 2876°F46°F94°F 196932°F 194740%1%
May 2976°F47°F94°F 189632°F 194740%1%
May 3077°F47°F100°F 200332°F 196439%1%
May 3177°F47°F96°F 199429°F 192239%1%

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.010203040501102030
  • Chance of a wet day
  • Chance of snowfall

Sunrise and sunset

Times for 2026, local time (MDT).

May 1
sunrise 6:01 AM, sunset 7:56 PM
May 31
sunrise 5:34 AM, sunset 8:24 PM

Every day of May: 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.