Climate Comfort Score
34/100
Below Average
NOAA 1991–2020 normals 41°F annual avg Public-domain federal data
Port San Juan, AK Climate
Annual temperature, rainfall, and a comfort score, sourced from NOAA NCEI's 1991–2020 normals →
- 41°F
- Avg annual temp
- 34/100
- Comfort score
- 137.9"
- Annual precip
- 150d
- Growing season
30-year climate normals from 1 weather station (1991-2020).
The climate verdict for Port San Juan
Port San Juan, Alaska averages 41°F a year and scores 34/100 on the comfort index - below average, milder than 1% of U.S. cities.
- 41°F
- yearly average temperature, NOAA normal
- 34/100
- comfort score, milder than 1% of U.S. cities
- 137.9"
- yearly precipitation total
- 150 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
41°F (5°C)
Avg High
46°F
Avg Low
36°F
Annual Precip
137.9"
Comfort Score
34/100
Below Average
Avg Annual Temperature
41°F
30-year mean (NOAA NCEI)
Annual Precipitation
137.9"
Liquid-equivalent total
Comfort score vs national 100-point ceiling (Port San Juan) 34.0%
National median (63)
PlainClimate composite, temperature mildness, humidity, precipitation, extreme-weather frequency. Below Average for the Port San Juan area.
How Port San Juan compares to every U.S. city
Port San Juan's comfort score vs. all U.S. cities
PlainClimate composite comfort index (1–100), NOAA 1991–2020 normals
34 Top 99% higher than 1% 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 Port San Juan
MethodologySince 1900, U.S. land temperatures have tracked (and diverged from) the global mean - the chart below shows how. Port San Juan'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 | 34°F (1°C) | 26°F (-3°C) | 30°F (-1°C) | 12.3" | 23.2 | 0.0 |
| February | 35°F (2°C) | 26°F (-3°C) | 31°F (-1°C) | 11.6" | 20.7 | 0.0 |
| March | 36°F (2°C) | 26°F (-3°C) | 31°F (0°C) | 9.6" | 24.3 | 0.0 |
| April | 43°F (6°C) | 32°F (0°C) | 37°F (3°C) | 10.3" | 14.7 | 0.0 |
| May | 52°F (11°C) | 37°F (3°C) | 45°F (7°C) | 8.1" | 3.3 | 0.0 |
| June | 59°F (15°C) | 44°F (7°C) | 52°F (11°C) | 4.5" | 0.1 | 0.0 |
| July | 63°F (17°C) | 50°F (10°C) | 56°F (13°C) | 5.3" | 0.0 | 0.0 |
| August | 61°F (16°C) | 49°F (10°C) | 55°F (13°C) | 9.8" | 0.0 | 0.0 |
| September | 54°F (12°C) | 44°F (6°C) | 49°F (9°C) | 17.4" | 0.6 | 0.0 |
| October | 45°F (7°C) | 36°F (2°C) | 41°F (5°C) | 17.3" | 7.9 | 0.0 |
| November | 38°F (3°C) | 30°F (-1°C) | 34°F (1°C) | 15.9" | 18.7 | 0.0 |
| December | 36°F (2°C) | 28°F (-2°C) | 32°F (0°C) | 15.8" | 22.1 | 0.0 |
Monthly Precipitation
Average monthly rainfall
January 12.3"
20.0 days with precipitation
February 11.6"
18.0 days with precipitation
March 9.6"
17.3 days with precipitation
April 10.3"
17.7 days with precipitation
May 8.1"
15.7 days with precipitation
June 4.5"
13.7 days with precipitation
July 5.3"
15.2 days with precipitation
August 9.8"
16.3 days with precipitation
September 17.4"
19.9 days with precipitation
October 17.3"
20.7 days with precipitation
November 15.9"
19.1 days with precipitation
December 15.8"
22.0 days with precipitation
Frost Dates & Growing Season
First Fall Freeze
October 7
50% probability date
Last Spring Freeze
May 10
50% probability date
Growing Season
150 days
Heating & Cooling Degree Days
Annual totals indicate energy demand for heating and cooling
Heating Degree Days
8,759
Higher = more heating needed
Cooling Degree Days
1
Higher = more cooling needed
Warmest Month
July
Coldest Month
January
What Port San Juan's climate means for you
Port San Juan runs 41°F a year - peaking in July, coldest in January.
- Gardeners get about 150 frost-free days, with the last spring freeze near May 10 - plan the planting calendar around it, not the regional average.
- Energy bills track 8,759 heating and 1 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: Port San Juan, AK
The NOAA 1991–2020 climate normals describe Port San Juan, Alaska as a location with an annual average temperature of 41°F, ranging from a mean daily high of 46°F to a mean daily low of 36°F. July is typically the warmest month of the year, while January is the coldest. These thirty-year averages, computed from station USC00507738, smooth out year-to-year variability and give a baseline expectation for typical conditions in any given month.
Beyond temperature, Port San Juan averages 137.9 inches of precipitation annually, predominantly as rainfall - a real factor for anyone planning to live, garden, or travel here. The frost-free season averages 150 days, which directly shapes the planting calendar and growing potential for the area, with the last spring freeze near May 10 and the first fall freeze near October 7. Turning to energy use, 8,759 heating degree days and 1 cooling degree days tell the story of how often furnaces and air conditioners run during a normal year.
On PlainClimate's composite comfort index, Port San Juan scores 34/100 (Below Average), 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 Port San Juan, AK? ▼
The average annual temperature in Port San Juan, Alaska is 41°F. The warmest month averages 63°F (17°C) and the coldest averages 26°F (-3°C).
How much rain does Port San Juan get? ▼
Port San Juan receives 137.9 inches of precipitation annually. Based on NOAA 30-year climate normals (1991-2020).
What is the comfort score for Port San Juan? ▼
Port San Juan has a climate comfort score of 34/100 (Below Average), milder than 1% of U.S. cities in the PlainClimate database.
When is the growing season in Port San Juan? ▼
Port San Juan has approximately 150 frost-free days per year, with the last spring freeze around May 10 and the first fall freeze around October 7.
How much energy does heating and cooling require in Port San Juan? ▼
Port San Juan has 8,759 heating degree days and 1 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 Port San Juan climate data come from? ▼
NOAA U.S. Climate Normals v1.0.1 (1991-2020), from weather station USC00507738 near Port San Juan.
Data Sources
Data source: NOAA U.S. Climate Normals v1.0.1 (1991-2020). Station: USC00507738. 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.