Climate Comfort Score
68/100
Good
NOAA 1991–2020 normals 52°F annual avg Public-domain federal data
Petersburg, IL Climate
Temperature, precipitation, and comfort score from NOAA NCEI 1991–2020 normals →
- 52°F
- Avg annual temp
- 68/100
- Comfort score
- 37.6"
- Annual precip
- 191d
- Growing season
30-year climate normals from 1 weather station (1991-2020).
The climate verdict for Petersburg
Petersburg, Illinois averages 52°F a year and scores 68/100 on the comfort index - good, milder than 58% of U.S. cities.
- 52°F
- average temperature, NOAA 1991-2020 normal
- 68/100
- comfort score, milder than 58% of U.S. cities
- 37.6"
- annual precipitation · 15" snow
- 191 days
- frost-free growing season
Based on NOAA U.S. Climate Normals (1991–2020) - 30-year averages describing the typical year, not a forecast.
Avg Temperature
52°F (11°C)
Avg High
63°F
Avg Low
42°F
Annual Precip
37.6"
Annual Snow
15.2"
Comfort Score
68/100
Good
Avg Annual Temperature
52°F
30-year mean (NOAA NCEI)
Annual Precipitation
37.6"
Plus 15.2" of snow
Comfort score vs national 100-point ceiling (Petersburg) 68.0%
National median (63)
PlainClimate composite, temperature mildness, humidity, precipitation, extreme-weather frequency. Good for the Petersburg area.
How Petersburg compares to every U.S. city
Petersburg's comfort score vs. all U.S. cities
PlainClimate composite comfort index (1–100), NOAA 1991–2020 normals
68 Top 42% higher than 58% 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 Petersburg
MethodologySince 1900, U.S. land temperatures have tracked (and diverged from) the global mean - the chart below shows how. Petersburg'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 | Snow | Freeze Days | 90°F+ Days |
|---|---|---|---|---|---|---|---|
| January | 34°F (1°C) | 17°F (-8°C) | 26°F (-3°C) | 2.0" | 5.4" | 27.2 | 0.0 |
| February | 39°F (4°C) | 21°F (-6°C) | 30°F (-1°C) | 1.8" | 2.7" | 23.8 | 0.0 |
| March | 51°F (10°C) | 30°F (-1°C) | 41°F (5°C) | 2.5" | 1.4" | 17.8 | 0.0 |
| April | 64°F (18°C) | 41°F (5°C) | 53°F (11°C) | 4.1" | 0.5" | 6.8 | 0.0 |
| May | 74°F (23°C) | 53°F (12°C) | 64°F (18°C) | 4.6" | 0.0" | 0.2 | 0.5 |
| June | 82°F (28°C) | 62°F (17°C) | 72°F (22°C) | 4.1" | 0.0" | 0.0 | 5.0 |
| July | 86°F (30°C) | 65°F (19°C) | 76°F (24°C) | 3.9" | 0.0" | 0.0 | 7.5 |
| August | 85°F (29°C) | 63°F (17°C) | 74°F (23°C) | 3.7" | 0.0" | 0.0 | 2.2 |
| September | 79°F (26°C) | 55°F (13°C) | 67°F (19°C) | 3.1" | 0.0" | 0.0 | 4.1 |
| October | 66°F (19°C) | 43°F (6°C) | 55°F (13°C) | 3.2" | 0.0" | 3.5 | 0.0 |
| November | 52°F (11°C) | 32°F (0°C) | 42°F (5°C) | 2.8" | 1.2" | 17.1 | 0.0 |
| December | 39°F (4°C) | 23°F (-5°C) | 31°F (-1°C) | 1.9" | 4.0" | 24.3 | 0.0 |
Monthly Precipitation
Average monthly rainfall and snowfall
January 2.0"
Snow: 5.4"
8.7 days with precipitation
February 1.8"
Snow: 2.7"
7.4 days with precipitation
March 2.5"
Snow: 1.4"
9.8 days with precipitation
April 4.1"
Snow: 0.5"
10.7 days with precipitation
May 4.6"
11.4 days with precipitation
June 4.1"
9.0 days with precipitation
July 3.9"
8.3 days with precipitation
August 3.7"
7.6 days with precipitation
September 3.1"
7.0 days with precipitation
October 3.2"
8.5 days with precipitation
November 2.8"
Snow: 1.2"
8.0 days with precipitation
December 1.9"
Snow: 4.0"
7.8 days with precipitation
Frost Dates & Growing Season
First Fall Freeze
October 21
50% probability date
Last Spring Freeze
April 13
50% probability date
Growing Season
191 days
Heating & Cooling Degree Days
Annual totals indicate energy demand for heating and cooling
Heating Degree Days
5,644
Higher = more heating needed
Cooling Degree Days
1,056
Higher = more cooling needed
Warmest Month
July
Coldest Month
January
What Petersburg's climate means for you
Petersburg runs 52°F a year - peaking in July, coldest in January.
- Gardeners get about 191 frost-free days, with the last spring freeze near April 13 - plan the planting calendar around it, not the regional average.
- Energy bills track 5,644 heating and 1,056 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: Petersburg, IL
Petersburg, Illinois runs an annual average of 52°F, ranging from a mean daily high of 63°F to a mean daily low of 42°F, per NOAA's 1991–2020 climate normals. July is typically the warmest month of the year, while January is the coldest. Drawn from station USC00116765, these thirty-year averages smooth out year-to-year swings into a baseline for what a typical month looks like here.
Anyone planning to live, garden, or travel in Petersburg should weigh precipitation alongside temperature: the annual average runs 37.6 inches, with 15.2 inches typically falling as snow. The frost-free season averages 191 days, which directly shapes the planting calendar and growing potential for the area, with the last spring freeze near April 13 and the first fall freeze near October 21. And on the energy front, 5,644 heating degree days and 1,056 cooling degree days tell the story of how often furnaces and air conditioners run during a normal year.
On PlainClimate's composite comfort index, Petersburg scores 68/100 (Good), a blended measure that weighs temperature mildness, precipitation moderation, and extreme-weather frequency against one another. Shoulder seasons bring the mildest highs and lows in the monthly tables above, summer brings July-driven heat, and winter brings January-driven cold - use that rhythm for planning. These figures are thirty-year averages rather than forecasts, so a specific year may still run warmer, cooler, wetter, or drier than what's shown.
Frequently Asked Questions
What is the average temperature in Petersburg, IL? ▼
The average annual temperature in Petersburg, Illinois is 52°F. The warmest month averages 86°F (30°C) and the coldest averages 17°F (-8°C).
How much rain does Petersburg get? ▼
Petersburg receives 37.6 inches of precipitation annually, including 15.2 inches of snow. Based on NOAA 30-year climate normals (1991-2020).
What is the comfort score for Petersburg? ▼
Petersburg has a climate comfort score of 68/100 (Good), milder than 58% of U.S. cities in the PlainClimate database.
When is the growing season in Petersburg? ▼
Petersburg has approximately 191 frost-free days per year, with the last spring freeze around April 13 and the first fall freeze around October 21.
How much energy does heating and cooling require in Petersburg? ▼
Petersburg has 5,644 heating degree days and 1,056 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 Petersburg climate data come from? ▼
NOAA U.S. Climate Normals v1.0.1 (1991-2020), from weather station USC00116765 near Petersburg.
Data Sources
Data source: NOAA U.S. Climate Normals v1.0.1 (1991-2020). Station: USC00116765. 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.