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 2018-02-14.

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%
16134
18%
48738
16%
16095
55%
16095
27%
31121

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
41%
812
8%
2752
8%
812
43%
812
14%
2046
January16th to endNight
42%
832
12%
2733
11%
832
44%
832
15%
2003
February1st to 15thNight
42%
756
9%
2470
10%
753
44%
753
16%
1810
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%
539
28%
1611
25%
536
79%
536
52%
791
August16th to endNight
73%
573
38%
1719
30%
573
77%
573
56%
803
September1st to 15thNight
69%
663
29%
1906
22%
663
75%
663
49%
988
September16th to endNight
68%
716
32%
1980
26%
716
72%
716
45%
1093
October1st to 15thNight
58%
720
25%
2104
20%
720
62%
720
37%
1203
October16th to endNight
60%
768
27%
2364
23%
768
65%
768
33%
1393
November1st to 15thNight
48%
760
19%
2470
19%
760
51%
760
24%
1596
November16th to endNight
44%
975
15%
2730
10%
975
48%
975
24%
1875
December1st to 15thNight
39%
975
8%
2730
5%
975
42%
975
18%
2055
December16th to endNight
31%
1040
8%
3084
5%
1040
34%
1040
12%
2462

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%7%25%42445%7%48%
49339
Night
9%8%35%42445%6%44%
48918
TransparencyDay
36%6%10%20%17%8%
49018
Night
39%5%12%19%14%7%
48739
SeeingDay
11%9%24%28%19%5%
6205
Night
14%420%36%20%3
16145

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%6%34447%29%
1526
16th to endDay
16%13%49%5%24345%29%
1840
February1st to 15thDay
11%11%49%7%35%5%5%6%29%
1693
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
2212313346%67%
2340
16th to endDay
2212322436%68%
2483
September1st to 15thDay
432212336%67%
2049
16th to endDay
6%212323346%63%
1980
October1st to 15thDay
10%5%23434446%50%
1855
16th to endDay
8%6%245%345%47%47%
1860
November1st to 15thDay
12%9%45%434345%42%
1706
16th to endDay
12%9%46%5%3445%6%38%
1560
December1st to 15thDay
14%11%5%9%7%34445%28%
1560
16th to endDay
15%15%5%8%6%24446%25%
1488
January1st to 15thNight
15%13%48%43335%7%30%
2752
16th to endNight
14%14%5%6%5%23345%32%
2733
February1st to 15thNight
12%12%5%7%5%3445%6%32%
2459
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
221232345%8%63%
1620
16th to endNight
212313437%67%
1719
September1st to 15thNight
5%213223346%64%
1906
16th to endNight
6%31332335%6%60%
1980
October1st to 15thNight
9%42442335%5%55%
2104
16th to endNight
9%5%24423446%51%
2364
November1st to 15thNight
13%8%34324446%43%
2470
16th to endNight
9%10%46%5%34446%40%
2730
December1st to 15thNight
13%11%47%7%34346%31%
2730
16th to endNight
17%17%6%8%6%3333425%
3084

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%8%17%12%5%
1526
16th to endDay
57%7%12%16%41
1840
February1st to 15thDay
55%9%13%16%4
1693
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
18%45%14%29%27%
2325
16th to endDay
17%35%18%32%22%
2483
September1st to 15thDay
19%47%19%32%16%
2049
16th to endDay
23%49%27%26%8%
1980
October1st to 15thDay
35%412%31%12%3
1855
16th to endDay
36%6%13%25%16%
1860
November1st to 15thDay
45%5%16%21%9%2
1706
16th to endDay
47%5%19%19%6%1
1560
December1st to 15thDay
57%9%12%17%3
1560
16th to endDay
61%7%16%10%3
1488
January1st to 15thNight
54%8%16%15%41
2752
16th to endNight
55%5%15%16%5%1
2733
February1st to 15thNight
52%8%16%16%5%
2470
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%47%15%23%29%
1611
16th to endNight
17%25%16%28%29%
1719
September1st to 15thNight
21%46%14%32%21%
1906
16th to endNight
24%5%7%25%27%9%
1980
October1st to 15thNight
31%313%29%17%3
2104
16th to endNight
33%5%10%29%19%2
2364
November1st to 15thNight
43%5%13%25%10%2
2470
16th to endNight
45%5%17%20%8%1
2730
December1st to 15thNight
53%7%19%15%3
2730
16th to endNight
64%5%13%12%31
3084

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
27%5%11%27%23%4
90
16th to endDay
29%419%29%13%2
137
February1st to 15thDay
23%12%25%17%17%3
130
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
4328%32%26%5%
315
16th to endDay
3324%31%23%13%
332
September1st to 15thDay
6%6%22%27%25%11%
315
16th to endDay
10%8%20%29%22%8%
315
October1st to 15thDay
13%8%24%23%24%4
190
16th to endDay
13%13%15%27%25%5%
144
November1st to 15thDay
19%6%17%24%19%13%
135
16th to endDay
22%9%22%34%9%
135
December1st to 15thDay
22%325%29%13%4
135
16th to endDay
26%7%24%29%5%6%
103
January1st to 15thNight
21%6%18%32%19%2
816
16th to endNight
23%416%33%18%2
832
February1st to 15thNight
20%5%22%34%15%1
760
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
5%111%43%35%2
539
16th to endNight
3117%39%34%4
573
September1st to 15thNight
6%117%35%30%7%
663
16th to endNight
9%215%33%30%9%
716
October1st to 15thNight
12%319%37%23%3
720
16th to endNight
12%317%41%20%4
768
November1st to 15thNight
16%5%22%33%19%2
760
16th to endNight
14%6%25%33%17%2
975
December1st to 15thNight
21%422%36%13%1
975
16th to endNight
27%6%22%30%12%1
1040
Page generated at 2018-02-15 08:58:39. Version ac04

Copyright 2018 A. Danko


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