Idaho Falls
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Idaho Falls clear sky chart from 2005-11-05 to 2017-08-12.

This page is a summary of past forecasts. Even though it's based only on forecasts, some people use these pages as clue to a site's climate. But climate data based on actual observation should be preferred (if you can find it!).

Cloud, Transparency and Seeing forecasts are summarized individually. But because good observing conditions require a combination of minimum cloud cover, transparency and seeing, the individual forecast summaries can be difficult to interpret. The observing conditions section counts the combinations of conditions needed for common types of astronomical observation.

Observing Conditions

The following tables count the occurrence of the combinations of forecast and darkness conditions needed for different observations. Conditions are rated by by what percentage of the hours the observation would likely be attempted are usable.
Observation TypeMinimum conditions for hour to be usableOut of hours
Clear of CloudsTransparencySeeingSky Brightness
Planetary:50%(no limit)Average(no limit)Nighttime Hours
Deep Sky:70%Average(no limit)5.9Nighttime Hours
CCD Imaging:70%Below AveragePoor(no limit)Nighttime Hours

Percentages are of nighttime hours per month, or per year, when a particular observing conditions was met. Deep Sky percentages never exceed 50% because the moon is up half the time. Deep sky percentages are much lower for charts at high latitudes because of fewer dark hours in the summer.

Overall

PlanetaryData
Pts
Deep Sky
Max 60%
Data
Pts
Both Planetary and Deep Sky
Max 60%
Data
Pts
Either Planetary or Deep SkyData
Pts
CCD ImagingData
Pts
Night
52%
15362
18%
46404
15%
15323
56%
15323
27%
29596

By Month

MonthDays of MonthPlanetaryData
Pts
Deep Sky
Max 60%
Data
Pts
Both Planetary and Deep Sky
Max 60%
Data
Pts
Either Planetary or Deep SkyData
Pts
CCD ImagingData
Pts
January1st to 15thNight
40%
749
9%
2539
8%
749
42%
749
14%
1894
January16th to endNight
42%
768
12%
2523
11%
768
44%
768
15%
1851
February1st to 15thNight
43%
700
9%
2288
9%
697
45%
697
15%
1684
February16th to endNight
39%
632
12%
1941
11%
632
43%
632
18%
1413
March1st to 15thNight
46%
720
12%
2038
10%
720
49%
720
21%
1472
March16th to endNight
43%
768
16%
2112
9%
768
47%
768
24%
1477
April1st to 15thNight
46%
632
15%
1814
11%
632
50%
632
25%
1211
April16th to endNight
47%
540
20%
1620
15%
540
51%
540
28%
1022
May1st to 15thNight
54%
539
18%
1619
16%
539
57%
539
33%
976
May16th to endNight
57%
561
17%
1577
15%
561
59%
561
30%
1008
June1st to 15thNight
58%
400
18%
1300
15%
400
64%
400
33%
726
June16th to endNight
71%
360
29%
1260
31%
360
79%
360
54%
531
July1st to 15thNight
80%
340
24%
1262
30%
340
86%
340
54%
513
July16th to endNight
79%
513
29%
1542
33%
480
81%
480
61%
654
August1st to 15thNight
78%
527
29%
1575
26%
524
79%
524
52%
769
August16th to endNight
71%
525
36%
1575
28%
525
75%
525
53%
753
September1st to 15thNight
68%
608
31%
1747
23%
608
74%
608
49%
913
September16th to endNight
69%
656
33%
1815
26%
656
73%
656
47%
975
October1st to 15thNight
60%
660
26%
1928
20%
660
64%
660
37%
1108
October16th to endNight
59%
704
25%
2167
21%
704
64%
704
31%
1307
November1st to 15thNight
50%
700
20%
2275
19%
700
53%
700
25%
1443
November16th to endNight
45%
900
15%
2520
10%
900
48%
900
24%
1729
December1st to 15thNight
37%
900
7%
2520
4%
900
40%
900
17%
1916
December16th to endNight
33%
960
8%
2847
6%
960
35%
960
13%
2251

Individual Forecasts

The length of each colored bar in the "occurrence of each Forecast" column is proportional to the number of times the chart forecast that color. The percentages are of the total number of hours per month, or per year, with a particular forecast. The colors as the same as those used in clear sky charts.

Note: Transparency probabilities are only counted for those hours that have 30% or less cloud cover. Seeing probabilities are only counted for those hours that have 80% or less cloud cover. If that's too tricky, try Observing Conditions instead.

Overall

Occurrence of each ForecastData
Points
Cloud CoverDay
8%6%25%42445%7%48%
47571
Night
9%8%35%42445%6%45%
46584
TransparencyDay
36%6%10%20%17%8%
47250
Night
39%5%12%19%14%7%
46405
SeeingDay
11%10%25%28%19%5%
5624
Night
14%420%36%20%3
15373

By Month

Percentage Cloud Cover SW (2006-)
Color Meanings:
Overcast 90% covered 80% covered 70% covered 60% covered 50% covered 40% covered 30% covered 20% covered 10% covered Clear
MonthDays in MonthOccurrence of each ForecastData
Points
January1st to 15thDay
13%12%5%8%5%34438%29%
1408
16th to endDay
15%13%49%5%24345%30%
1698
February1st to 15thDay
11%11%49%7%345%5%6%30%
1575
16th to endDay
8%11%47%6%35%45%8%33%
1530
March1st to 15thDay
7%9%5%8%6%35%45%8%34%
1921
16th to endDay
10%13%47%5%35%5%5%7%32%
2112
April1st to 15thDay
8%10%36%5%25%5%7%8%36%
2133
16th to endDay
9%7%35%5%24447%43%
2340
May1st to 15thDay
6%5%25%4345%5%8%49%
2331
16th to endDay
10%7%35%5%345%6%7%41%
2537
June1st to 15thDay
8%424435%5%6%8%46%
2658
16th to endDay
222212345%71%
2700
July1st to 15thDay
211221335%8%66%
2619
16th to endDay
212313445%68%
2518
August1st to 15thDay
222323346%68%
2290
16th to endDay
222322436%68%
2275
September1st to 15thDay
4412212345%67%
1879
16th to endDay
6%11231335%6%65%
1815
October1st to 15thDay
10%5%23434446%50%
1701
16th to endDay
9%6%245%345%5%7%45%
1705
November1st to 15thDay
12%8%45%434345%43%
1572
16th to endDay
11%9%46%5%34446%39%
1440
December1st to 15thDay
14%12%5%9%7%34445%28%
1440
16th to endDay
15%14%5%7%6%24446%26%
1374
January1st to 15thNight
16%13%48%433347%29%
2539
16th to endNight
15%14%6%7%5%23345%32%
2523
February1st to 15thNight
13%12%47%5%3445%6%31%
2277
16th to endNight
9%11%5%7%5%346%5%7%32%
1941
March1st to 15thNight
7%9%46%7%45%5%5%7%35%
2038
16th to endNight
9%9%36%6%3446%7%37%
2112
April1st to 15thNight
9%7%36%5%35%46%7%39%
1814
16th to endNight
9%8%25%434346%47%
1620
May1st to 15thNight
6%6%244245%5%9%47%
1619
16th to endNight
10%5%23425%5%6%7%45%
1576
June1st to 15thNight
7%413425%5%7%8%48%
1300
16th to endNight
223212336%70%
1260
July1st to 15thNight
1121135%6%9%65%
1338
16th to endNight
111222335%6%69%
1649
August1st to 15thNight
321232345%8%64%
1584
16th to endNight
2213413437%66%
1575
September1st to 15thNight
4213223346%64%
1747
16th to endNight
6%21232335%6%62%
1815
October1st to 15thNight
9%42442335%5%54%
1928
16th to endNight
10%5%245%23446%49%
2167
November1st to 15thNight
12%8%34423346%45%
2275
16th to endNight
9%9%46%5%34446%40%
2520
December1st to 15thNight
14%11%47%7%34346%31%
2520
16th to endNight
17%16%5%7%6%3343426%
2847

Transparency (when cloud cover <= 30%)
Color Meanings:
Too cloudy to forecast Poor Below Average Average Above average Transparent
MonthDays in MonthOccurrence of each ForecastData
Points
January1st to 15thDay
55%7%17%12%5%
1408
16th to endDay
57%7%12%16%41
1698
February1st to 15thDay
54%9%13%17%4
1575
16th to endDay
51%9%14%19%5%1
1530
March1st to 15thDay
48%10%13%20%5%1
1921
16th to endDay
53%6%12%19%7%
2112
April1st to 15thDay
44%7%15%19%11%
2133
16th to endDay
40%6%11%26%14%1
2340
May1st to 15thDay
33%7%9%28%19%2
2331
16th to endDay
40%9%10%24%12%1
2540
June1st to 15thDay
35%6%10%25%18%3
2658
16th to endDay
15%36%19%36%18%
2700
July1st to 15thDay
16%36%16%31%24%
2466
16th to endDay
17%3413%24%37%
2362
August1st to 15thDay
17%45%13%29%28%
2275
16th to endDay
18%4417%32%22%
2275
September1st to 15thDay
20%47%19%33%15%
1879
16th to endDay
21%49%27%27%9%
1815
October1st to 15thDay
36%413%30%11%3
1701
16th to endDay
38%6%13%24%15%
1705
November1st to 15thDay
44%5%16%21%9%2
1572
16th to endDay
46%420%20%6%1
1440
December1st to 15thDay
58%8%11%16%3
1440
16th to endDay
60%7%17%10%3
1374
January1st to 15thNight
55%8%16%14%31
2539
16th to endNight
56%5%14%17%41
2523
February1st to 15thNight
53%8%15%16%5%
2288
16th to endNight
51%7%15%18%5%1
1941
March1st to 15thNight
47%8%13%21%7%1
2038
16th to endNight
46%6%13%24%7%
2112
April1st to 15thNight
41%6%15%22%11%1
1814
16th to endNight
39%5%11%26%17%
1620
May1st to 15thNight
33%6%10%25%21%2
1620
16th to endNight
36%7%11%26%16%2
1577
June1st to 15thNight
30%5%13%22%24%4
1300
16th to endNight
15%26%14%36%23%
1260
July1st to 15thNight
14%47%17%27%28%
1262
16th to endNight
13%26%12%24%40%
1542
August1st to 15thNight
18%46%15%24%30%
1575
16th to endNight
18%35%15%28%29%
1575
September1st to 15thNight
22%36%13%33%20%
1747
16th to endNight
22%5%7%25%28%10%
1815
October1st to 15thNight
32%314%29%17%3
1928
16th to endNight
34%5%10%28%17%2
2167
November1st to 15thNight
41%5%13%25%10%3
2275
16th to endNight
45%5%17%20%9%1
2520
December1st to 15thNight
54%7%19%14%3
2520
16th to endNight
63%5%14%12%3
2847

Seeing (when cloud cover <= 80%)
Color Meanings:
Too cloudy to forecast Bad 1/5 Poor 2/5 Average 3/5 Good 4/5 Excellent 5/5
MonthDays in MonthOccurrence of each ForecastData
Points
January1st to 15thDay
26%6%6%30%23%6%
60
16th to endDay
31%212%31%17%4
91
February1st to 15thDay
25%11%21%14%23%4
90
16th to endDay
16%18%30%23%8%1
189
March1st to 15thDay
12%27%27%24%7%
270
16th to endDay
19%20%34%18%7%
288
April1st to 15thDay
15%20%27%19%12%4
269
16th to endDay
14%16%31%23%10%2
270
May1st to 15thDay
8%11%31%27%15%5%
288
16th to endDay
14%5%21%26%21%9%
438
June1st to 15thDay
9%11%22%28%23%5%
495
16th to endDay
46%25%30%27%6%
495
July1st to 15thDay
3318%33%32%8%
400
16th to endDay
2424%40%22%4
327
August1st to 15thDay
4329%32%26%5%
300
16th to endDay
3427%30%21%11%
268
September1st to 15thDay
7%7%27%30%20%5%
255
16th to endDay
7%7%23%29%22%9%
255
October1st to 15thDay
15%6%22%24%25%4
141
16th to endDay
15%13%17%21%25%6%
96
November1st to 15thDay
13%311%26%25%20%
90
16th to endDay
23%8%27%32%7%
90
December1st to 15thDay
30%5%31%26%6%
90
16th to endDay
18%5%20%36%8%10%
69
January1st to 15thNight
22%6%18%31%18%2
753
16th to endNight
23%416%33%19%3
768
February1st to 15thNight
21%5%20%34%16%2
704
16th to endNight
15%7%28%32%12%2
632
March1st to 15thNight
12%6%24%37%15%2
720
16th to endNight
13%8%28%37%11%1
768
April1st to 15thNight
13%7%25%35%16%1
632
16th to endNight
13%7%25%36%15%2
540
May1st to 15thNight
10%424%35%23%1
540
16th to endNight
12%418%37%22%3
563
June1st to 15thNight
10%323%38%22%2
400
16th to endNight
3219%40%27%5%
360
July1st to 15thNight
212%42%36%5%
340
16th to endNight
213%43%35%4
513
August1st to 15thNight
4111%44%34%3
527
16th to endNight
3118%40%32%4
525
September1st to 15thNight
6%118%37%28%7%
608
16th to endNight
8%115%33%30%9%
656
October1st to 15thNight
12%318%39%23%3
660
16th to endNight
12%317%40%20%5%
704
November1st to 15thNight
16%5%22%34%19%2
700
16th to endNight
14%7%25%34%17%2
900
December1st to 15thNight
22%5%24%34%12%1
900
16th to endNight
26%6%21%30%13%1
960
Page generated at 2017-08-13 12:16:51. Version ac04

Copyright 2017 A. Danko


Idaho Falls Clear Sky Chart | Charts Home