Iliamna weather in September: Iliamna, Alaska: normal highs, lows, rain and records for September
Iliamna in September has a normal high of 56°F and a normal low of 43°F, a daily mean of 50°F, falling from 61°F on the 1st to 51°F by the 30th. Measurable precipitation falls on 16 days in a normal September, 5.01 inches in all. (NOAA 1991-2020 normals)
In metric: a normal high of 13°C and low of 6°C, 127 mm of precipitation in September.
- NOAA stationIliamna Airport
- Station IDUSW00025506
- Location59.75°N 154.91°W
- Elevation143 ft (44 m)
- Population (census place)45
- Jan 25° 12°
- Feb 30° 16°
- Mar 32° 16°
- Apr 43° 29°
- May 55° 38°
- Jun 62° 45°
- Jul 65° 51°
- Aug 64° 50°
- Sep 56° 43°
- Oct 45° 32°
- Nov 33° 21°
- Dec 28° 15°
Each month: normal high (large) and low, °F. Fill: the month's normal mean, colder blue to hotter red.
How warm is Iliamna in September?
The normal high is 56°F and the normal low 43°F, for a daily mean of 49.7°F. September is 7.0°F cooler than August and 11.3°F warmer than October. September is the 4th warmest month of the year in Iliamna and the wettest. Across the month the normal high falls 10°F, from 61°F on September 1 to 51°F on September 30. From one year to the next September's mean temperature typically moves about 2.7°F either way (NOAA's standard deviation), so roughly two Septembers in three average between 47°F and 52°F.
Bars above: each day's normal high to low. Columns below: the chance of 0.01 inch or more of precipitation that day, on a scale of 0 to 100% (highest 55%).
| Day | High | Low | Chance of 0.01 in | Chance of 0.10 in |
|---|---|---|---|---|
| September 1 | 61°F | 47°F | 55% | 33% |
| September 8 | 59°F | 46°F | 55% | 34% |
| September 15 | 56°F | 44°F | 55% | 34% |
| September 22 | 54°F | 41°F | 53% | 33% |
| September 30 | 51°F | 39°F | 50% | 31% |
Every day of September: normal high, low and chance of precipitation (warmest afternoon September 1, coldest night September 30)
| Day | High | Low | Chance of 0.01 in | Chance of 0.10 in | Daylight |
|---|---|---|---|---|---|
| September 1 | 61°F | 47°F | 55% | 33% | 14 h 10 min |
| September 2 | 60°F | 47°F | 55% | 33% | 14 h 10 min |
| September 3 | 60°F | 47°F | 55% | 34% | 14 h |
| September 4 | 60°F | 47°F | 55% | 34% | 14 h |
| September 5 | 59°F | 46°F | 55% | 34% | 13 h 50 min |
| September 6 | 59°F | 46°F | 55% | 34% | 13 h 50 min |
| September 7 | 59°F | 46°F | 55% | 34% | 13 h 40 min |
| September 8 | 59°F | 46°F | 55% | 34% | 13 h 40 min |
| September 9 | 58°F | 45°F | 55% | 34% | 13 h 30 min |
| September 10 | 58°F | 45°F | 55% | 34% | 13 h 30 min |
| September 11 | 58°F | 45°F | 55% | 34% | 13 h 20 min |
| September 12 | 57°F | 44°F | 55% | 34% | 13 h 20 min |
| September 13 | 57°F | 44°F | 55% | 34% | 13 h 10 min |
| September 14 | 57°F | 44°F | 55% | 34% | 13 h |
| September 15 | 56°F | 44°F | 55% | 34% | 13 h |
| September 16 | 56°F | 43°F | 54% | 34% | 12 h 50 min |
| September 17 | 56°F | 43°F | 54% | 34% | 12 h 50 min |
| September 18 | 55°F | 43°F | 54% | 34% | 12 h 40 min |
| September 19 | 55°F | 42°F | 54% | 34% | 12 h 40 min |
| September 20 | 55°F | 42°F | 53% | 33% | 12 h 30 min |
| September 21 | 54°F | 42°F | 53% | 33% | 12 h 30 min |
| September 22 | 54°F | 41°F | 53% | 33% | 12 h 20 min |
| September 23 | 54°F | 41°F | 53% | 33% | 12 h 20 min |
| September 24 | 53°F | 41°F | 52% | 33% | 12 h 10 min |
| September 25 | 53°F | 41°F | 52% | 32% | 12 h 10 min |
| September 26 | 53°F | 40°F | 51% | 32% | 12 h |
| September 27 | 52°F | 40°F | 51% | 32% | 12 h |
| September 28 | 52°F | 40°F | 51% | 31% | 11 h 50 min |
| September 29 | 52°F | 39°F | 50% | 31% | 11 h 40 min |
| September 30 | 51°F | 39°F | 50% | 31% | 11 h 40 min |
- Normal high
- 56°FSeptember average
- Normal low
- 43°FSeptember average
- Precipitation
- 5.01 inmonth total
- Days with precipitation
- 160.01 inch or more
- Nights at 32°F or colder
- 2
- Daylight
- 14 h 10 min to 11 h 40 minSeptember 1 to September 30
- Sunshine
- 59%of clear-sky sunlight (NASA)
Source: NOAA NCEI 1991-2020 daily normals, station USW00025506; monthly normals. Daylight is computed from the place's latitude with NOAA's solar equations.
Does it rain in Iliamna in September?
On a given September day the chance of 0.01 inch or more is 54% on average, highest around September 7 (55%). In all, 5.01 in falls on 16 days of a normal September, 1 of them with an inch or more.
In a normal September in Iliamna, 2 nights fall to freezing.
Source: NOAA NCEI 1991-2020 daily and monthly normals, station USW00025506.
How humid and windy is Iliamna in September?
At 3 p.m. the normal temperature is 48°F with 64% relative humidity and a dew point of 37°F; at 6 a.m. it is 40°F with 82% humidity. The wind averages 10.1 mph, most often from the east-northeast in the afternoon. A dew point under 50°F feels dry.
| Time | Temperature | Dew point | Humidity | Wind | Clear or few clouds |
|---|---|---|---|---|---|
| 6 a.m. | 40°F | 35°F | 82% | 9.7 mph | – |
| 9 a.m. | 42°F | 36°F | 80% | 9.8 mph | 28% |
| noon | 46°F | 37°F | 69% | 11.0 mph | 38% |
| 3 p.m. | 48°F | 37°F | 64% | 11.6 mph | 28% |
| 6 p.m. | 47°F | 37°F | 68% | 10.2 mph | 33% |
| 9 p.m. | 43°F | 36°F | 77% | 9.5 mph | – |
Source: NOAA NCEI 1991-2020 hourly normals, station USW00025506. Hourly normals exist only for NOAA's first-order stations; a dash where NOAA publishes no value for that hour (the sky at some hours).
What are the records for September in Iliamna?
The warmest September temperature on this station's record (since 1920) is 75°F, on September 12, 2018; the coldest is 20°F, on September 27, 1921. The wettest September brought 11.02 in (1961); the snowiest, 1.0 inches (1996).
The September mean against the 1991-2020 normal of 49.7°F: 2021 45.6°F (−4.1), 2022 48.3°F (−1.4), 2023 46.3°F (−3.4), 2024 48.8°F (−0.9). 0 of 4 ran warmer than normal.
| September | Mean | Against normal | Precip. |
|---|---|---|---|
| 2021 | 45.6°F | −4.1°F | 1.65 in |
| 2022 | 48.3°F | −1.4°F | 7.94 in |
| 2023 | 46.3°F | −3.4°F | 3.12 in |
| 2024 | 48.8°F | −0.9°F | 4.22 in |
Source: records: ACIS, station USW00025506; recent months: ACIS, station USW00025506. Records and recent months use complete months only.
How does September in Iliamna compare across Alaska?
Across the 85 places PlainClimate covers in Alaska, September normal highs run from 37°F in Utqiaġvik to 60°F in Klawock; Iliamna's is 56°F.
Source: NOAA NCEI 1991-2020 monthly normals for every station in the state.