Climate Comfort Score
54/100
Moderate
NOAA 1991–2020 normals 40°F annual avg 2 stations
ST Mary, MT Climate
Explore average temperature, rainfall, and comfort score sourced from NOAA NCEI's 1991–2020 climate normals →
- 40°F
- Avg annual temp
- 54/100
- Comfort score
- 26.1"
- Annual precip
- 97d
- Growing season
30-year climate normals from 2 weather stations (1991-2020).
The climate verdict for ST Mary
ST Mary, Montana averages 40°F a year and scores 54/100 on the comfort index - moderate, milder than 27% of U.S. cities.
- 40°F
- average temperature, NOAA 1991-2020 normal
- 54/100
- comfort score, milder than 27% of U.S. cities
- 26.1"
- annual precipitation
- 97 days
- growing season, frost-free days
Based on NOAA U.S. Climate Normals (1991–2020) - 30-year averages describing the typical year, not a forecast.
Avg Temperature
40°F (4°C)
Avg High
49°F
Avg Low
30°F
Annual Precip
26.1"
Comfort Score
54/100
Moderate
Avg Annual Temperature
40°F
30-year mean (NOAA NCEI)
Annual Precipitation
26.1"
Liquid-equivalent total
Comfort score vs national 100-point ceiling (ST Mary) 54.0%
National median (63)
PlainClimate composite, temperature mildness, humidity, precipitation, extreme-weather frequency. Moderate for the ST Mary area.
How ST Mary compares to every U.S. city
ST Mary's comfort score vs. all U.S. cities
PlainClimate composite comfort index (1–100), NOAA 1991–2020 normals
54 Top 73% higher than 27% of 6,915 US cities
Each bar is a band; taller bars hold more US cities. The dashed line + filled bar mark this entry. Hover or tap any bar for its full count, share, and where it sits relative to this entry.
Source NOAA U.S. Climate Normals, PlainClimate comfort index · 1991–2020
Warming context for ST Mary
MethodologySince 1900, U.S. land temperatures have tracked (and diverged from) the global mean - the chart below shows how. ST Mary's current NOAA 1991-2020 normal sits within that longer spread, and the most recent decade runs warmer than the 30-year mean.
- United States land mean (NOAA NCEI) +0.11 °C/decade
- Global anomaly (NASA GISTEMP) +0.11 °C/decade
- Paris Agreement thresholds 1.5°C / 2.0°C
Monthly Temperatures
Average daily high and low temperatures by month
| Month | Avg High | Avg Low | Mean | Precip | Freeze Days | 90°F+ Days |
|---|---|---|---|---|---|---|
| January | 32°F (0°C) | 15°F (-9°C) | 23°F (-5°C) | 2.1" | 26.5 | 0.0 |
| February | 31°F (0°C) | 15°F (-10°C) | 23°F (-5°C) | 2.1" | 25.8 | 0.0 |
| March | 38°F (3°C) | 20°F (-7°C) | 29°F (-2°C) | 2.5" | 25.4 | 0.0 |
| April | 46°F (8°C) | 28°F (-2°C) | 37°F (3°C) | 2.5" | 20.8 | 0.0 |
| May | 56°F (13°C) | 35°F (2°C) | 46°F (8°C) | 2.8" | 10.7 | 0.0 |
| June | 63°F (17°C) | 42°F (5°C) | 52°F (11°C) | 3.1" | 1.7 | 0.0 |
| July | 73°F (23°C) | 46°F (8°C) | 60°F (15°C) | 1.2" | 0.0 | 0.5 |
| August | 73°F (23°C) | 45°F (7°C) | 59°F (15°C) | 1.3" | 0.6 | 0.1 |
| September | 63°F (17°C) | 39°F (4°C) | 51°F (11°C) | 1.6" | 6.0 | 0.0 |
| October | 49°F (9°C) | 32°F (0°C) | 40°F (5°C) | 2.2" | 15.1 | 0.0 |
| November | 37°F (3°C) | 25°F (-4°C) | 31°F (-1°C) | 2.7" | 21.0 | 0.0 |
| December | 31°F (-1°C) | 17°F (-8°C) | 24°F (-5°C) | 2.1" | 27.1 | 0.0 |
Monthly Precipitation
Average monthly rainfall
January 2.1"
14.8 days with precipitation
February 2.1"
14.1 days with precipitation
March 2.5"
16.0 days with precipitation
April 2.5"
14.7 days with precipitation
May 2.8"
12.9 days with precipitation
June 3.1"
12.8 days with precipitation
July 1.2"
8.1 days with precipitation
August 1.3"
7.9 days with precipitation
September 1.6"
8.9 days with precipitation
October 2.2"
12.3 days with precipitation
November 2.7"
14.0 days with precipitation
December 2.1"
14.3 days with precipitation
Frost Dates & Growing Season
First Fall Freeze
September 8
50% probability date
Last Spring Freeze
June 3
50% probability date
Growing Season
97 days
Heating & Cooling Degree Days
Annual totals indicate energy demand for heating and cooling
Heating Degree Days
9,282
Higher = more heating needed
Cooling Degree Days
21
Higher = more cooling needed
Warmest Month
July
Coldest Month
February
What ST Mary's climate means for you
ST Mary runs 40°F a year - peaking in July, coldest in February.
- Gardeners get about 97 frost-free days, with the last spring freeze near June 3 - plan the planting calendar around it, not the regional average.
- Energy bills track 9,282 heating and 21 cooling degree days a year, higher means the furnace or AC runs more.
- Comparing places to live? Line this city up against nearby cities and the national rankings. See rankings
These are 30-year NOAA normals (1991–2020) - the typical year, not a forecast for any specific season.
Climate Guides
Climate Insight: ST Mary, MT
In ST Mary, Montana, the NOAA 1991–2020 climate normals put the annual average temperature at 40°F, ranging from a mean daily high of 49°F to a mean daily low of 30°F. July is typically the warmest month of the year, while February is the coldest. As thirty-year averages computed from 2 weather stations, these numbers smooth out year-to-year noise into a working baseline for a typical month.
Anyone planning to live, garden, or travel in ST Mary should weigh precipitation alongside temperature: the annual average runs 26.1 inches, predominantly as rainfall. The frost-free season averages 97 days, which directly shapes the planting calendar and growing potential for the area, with the last spring freeze near June 3 and the first fall freeze near September 8. And on the energy front, 9,282 heating degree days and 21 cooling degree days tell the story of how often furnaces and air conditioners run during a normal year.
On PlainClimate's composite comfort index, ST Mary scores 54/100 (Moderate), a blended measure that weighs temperature mildness, precipitation moderation, and extreme-weather frequency against one another. The monthly tables above turn that into a planning tool: expect the mildest highs and lows in the shoulder seasons, July-driven heat at the peak of summer, and February-driven cold at the depth of winter. Every number here is a thirty-year average, not a forecast, so any given year can and does run warmer, cooler, wetter, or drier than the normal.
Frequently Asked Questions
What is the average temperature in ST Mary, MT? ▼
The average annual temperature in ST Mary, Montana is 40°F. The warmest month averages 73°F (23°C) and the coldest averages 15°F (-10°C).
How much rain does ST Mary get? ▼
ST Mary receives 26.1 inches of precipitation annually. Based on NOAA 30-year climate normals (1991-2020).
What is the comfort score for ST Mary? ▼
ST Mary has a climate comfort score of 54/100 (Moderate), milder than 27% of U.S. cities in the PlainClimate database.
When is the growing season in ST Mary? ▼
ST Mary has approximately 97 frost-free days per year, with the last spring freeze around June 3 and the first fall freeze around September 8.
How much energy does heating and cooling require in ST Mary? ▼
ST Mary has 9,282 heating degree days and 21 cooling degree days annually, a heating-dominated climate. See our <a href="/guides/reading-weather-data/" class="underline hover:text-brand-600">guide to reading weather data</a> for what these figures mean.
Where does this ST Mary climate data come from? ▼
NOAA U.S. Climate Normals v1.0.1 (1991-2020), from 2 weather stations near ST Mary.
Data Sources
Data source: NOAA U.S. Climate Normals v1.0.1 (1991-2020). Station: USW00004130. For informational purposes only.
Read our methodology - how this data is sourced, computed, and verified.
Related
Data sourced from official public datasets. See our methodology for details. Retrieved and formatted by PlainClimate Editorial
Every figure on PlainClimate is rendered directly from NOAA 1991-2020 U.S. Climate Normals data, no number is typed in by an editor. This page draws directly on NOAA 1991-2020 U.S. Climate Normals data, no figure is typed in by an editor. See our editorial standards & corrections policy, the methodology behind these numbers, or report a data error.