Idaho City
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Idaho City clear sky chart from 2005-11-05 to 2017-10-16.

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
59%
14883
20%
47145
19%
14859
61%
14859
28%
29046

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
45%
716
11%
2506
10%
716
49%
716
14%
1842
January16th to endNight
52%
768
15%
2688
18%
768
53%
768
20%
1788
February1st to 15thNight
47%
696
11%
2256
10%
696
50%
696
18%
1606
February16th to endNight
43%
632
12%
1895
12%
632
45%
632
17%
1409
March1st to 15thNight
44%
720
10%
2142
10%
720
46%
720
17%
1576
March16th to endNight
45%
768
14%
2058
10%
768
48%
768
22%
1476
April1st to 15thNight
51%
719
19%
1799
10%
719
54%
719
27%
1237
April16th to endNight
54%
558
25%
1638
17%
558
58%
558
34%
976
May1st to 15thNight
60%
539
23%
1619
18%
539
65%
539
39%
896
May16th to endNight
67%
390
18%
1512
24%
390
69%
390
27%
827
June1st to 15thNight
67%
360
17%
1440
24%
360
71%
360
28%
772
June16th to endNight
77%
360
24%
1440
38%
360
81%
360
41%
632
July1st to 15thNight
87%
340
24%
1360
39%
340
89%
340
52%
529
July16th to endNight
85%
376
34%
1416
48%
354
87%
354
57%
520
August1st to 15thNight
80%
494
33%
1567
31%
492
82%
492
52%
724
August16th to endNight
82%
675
37%
1821
26%
675
84%
675
62%
868
September1st to 15thNight
84%
720
34%
1860
25%
720
85%
720
63%
933
September16th to endNight
71%
716
34%
1980
29%
716
74%
716
44%
1114
October1st to 15thNight
66%
720
27%
2018
23%
720
70%
720
40%
1150
October16th to endNight
60%
708
23%
2301
22%
708
63%
708
29%
1379
November1st to 15thNight
57%
700
21%
2275
22%
700
59%
700
24%
1466
November16th to endNight
49%
720
15%
2346
14%
720
52%
720
21%
1593
December1st to 15thNight
47%
720
10%
2520
9%
720
51%
720
16%
1767
December16th to endNight
38%
768
13%
2688
12%
768
40%
768
14%
1966

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
10%9%35%424446%45%
48293
Night
11%9%34424446%45%
47318
TransparencyDay
38%49%20%17%9%
47964
Night
39%411%21%16%7%
47147
SeeingDay
15%12%31%26%11%2
5469
Night
15%311%36%27%4
14897

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%14%6%6%5%3445%5%29%
1432
16th to endDay
13%14%46%5%33346%33%
1536
February1st to 15thDay
14%14%6%6%6%34445%28%
1604
16th to endDay
10%20%7%8%6%24345%23%
1579
March1st to 15thDay
13%16%5%8%5%3445%6%25%
1816
16th to endDay
16%17%5%7%4245%47%24%
2164
April1st to 15thDay
12%13%46%6%3445%7%29%
2149
16th to endDay
11%12%34424345%41%
2322
May1st to 15thDay
8%7%25%5%35%448%43%
2331
16th to endDay
11%8%37%6%445%5%6%36%
2596
June1st to 15thDay
13%6%26%5%3445%7%40%
2520
16th to endDay
5%312313345%65%
2520
July1st to 15thDay
3212312346%68%
2520
16th to endDay
221221224472%
2657
August1st to 15thDay
322313445%67%
2385
16th to endDay
222212345%71%
2379
September1st to 15thDay
4212212235%69%
2100
16th to endDay
9%6%23213346%56%
1980
October1st to 15thDay
10%6%25%423446%48%
1941
16th to endDay
11%9%36%5%345%45%41%
1591
November1st to 15thDay
16%10%345%2445%7%34%
1584
16th to endDay
14%14%35%434446%34%
1611
December1st to 15thDay
18%13%6%6%423445%30%
1440
16th to endDay
19%15%5%8%5%24335%26%
1536
January1st to 15thNight
16%15%45%5%34436%30%
2506
16th to endNight
13%16%35%323347%37%
2688
February1st to 15thNight
14%16%35%424346%33%
2245
16th to endNight
13%15%5%7%6%24446%27%
1895
March1st to 15thNight
16%15%46%6%33445%31%
2142
16th to endNight
13%13%35%4345%48%32%
2058
April1st to 15thNight
10%9%45%5%35%5%5%6%39%
1799
16th to endNight
11%5%24334345%50%
1638
May1st to 15thNight
5%4134245%6%7%53%
1619
16th to endNight
8%426%435%46%8%44%
1512
June1st to 15thNight
11%413425%45%7%48%
1440
16th to endNight
421232345%5%63%
1440
July1st to 15thNight
2321335%7%68%
1440
16th to endNight
211221223474%
1512
August1st to 15thNight
3213313346%66%
1575
16th to endNight
122213445%72%
1821
September1st to 15thNight
2212212335%72%
1860
16th to endNight
10%32332333459%
1980
October1st to 15thNight
9%313423446%55%
2018
16th to endNight
12%7%2432345%7%44%
2301
November1st to 15thNight
17%8%2442445%6%39%
2275
16th to endNight
15%12%35%5%33447%35%
2346
December1st to 15thNight
15%11%46%5%35%46%6%30%
2520
16th to endNight
17%17%6%7%423346%26%
2688

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%14%16%4
1432
16th to endDay
52%5%16%17%7%
1536
February1st to 15thDay
56%6%14%16%5%
1604
16th to endDay
60%413%16%4
1579
March1st to 15thDay
57%5%12%16%6%
1816
16th to endDay
57%5%11%18%6%
2164
April1st to 15thDay
52%413%19%8%
2149
16th to endDay
43%410%25%15%
2322
May1st to 15thDay
37%49%31%15%2
2331
16th to endDay
45%5%10%24%12%2
2600
June1st to 15thDay
41%5%7%23%18%3
2520
16th to endDay
20%2321%34%15%
2520
July1st to 15thDay
17%2216%32%28%
2371
16th to endDay
13%219%28%44%
2490
August1st to 15thDay
18%4415%30%27%
2368
16th to endDay
14%2218%38%23%
2379
September1st to 15thDay
18%2418%33%22%
2100
16th to endDay
28%35%28%24%9%
1980
October1st to 15thDay
35%410%25%20%3
1941
16th to endDay
43%5%10%22%17%
1591
November1st to 15thDay
47%5%14%20%10%
1584
16th to endDay
50%413%21%8%1
1611
December1st to 15thDay
55%419%17%3
1440
16th to endDay
59%5%13%16%4
1536
January1st to 15thNight
55%6%14%16%5%1
2506
16th to endNight
47%5%14%22%9%
2688
February1st to 15thNight
51%6%14%21%5%
2256
16th to endNight
56%414%17%5%1
1895
March1st to 15thNight
55%412%19%6%1
2142
16th to endNight
48%5%14%21%9%
2058
April1st to 15thNight
42%5%11%26%12%1
1799
16th to endNight
35%211%30%19%
1638
May1st to 15thNight
27%5%10%35%19%2
1620
16th to endNight
34%5%11%32%14%2
1513
June1st to 15thNight
33%49%29%18%4
1440
16th to endNight
20%45%21%32%15%
1440
July1st to 15thNight
15%2315%33%29%
1360
16th to endNight
13%1110%29%42%
1416
August1st to 15thNight
18%3314%31%28%
1567
16th to endNight
13%3216%33%29%
1821
September1st to 15thNight
15%25%17%34%24%
1860
16th to endNight
28%2423%27%13%
1980
October1st to 15thNight
29%310%30%21%4
2018
16th to endNight
37%412%24%19%1
2301
November1st to 15thNight
44%413%21%15%1
2275
16th to endNight
48%5%13%22%8%2
2346
December1st to 15thNight
51%6%18%16%6%
2520
16th to endNight
59%313%18%5%
2688

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
21%121%20%25%10%
60
16th to endDay
21%425%20%23%4
64
February1st to 15thDay
24%5%24%22%17%6%
157
16th to endDay
27%13%31%20%5%
238
March1st to 15thDay
27%15%32%18%5%
270
16th to endDay
28%22%27%16%5%
288
April1st to 15thDay
18%18%31%19%9%2
269
16th to endDay
22%20%32%17%4
270
May1st to 15thDay
16%15%31%26%7%1
288
16th to endDay
18%8%27%26%13%5%
330
June1st to 15thDay
13%15%33%23%11%2
315
16th to endDay
8%14%35%29%10%1
315
July1st to 15thDay
5%9%30%38%12%3
305
16th to endDay
214%39%30%10%1
327
August1st to 15thDay
5%9%40%34%8%2
315
16th to endDay
311%32%31%17%4
332
September1st to 15thDay
8%11%26%34%13%5%
315
16th to endDay
13%7%32%29%16%1
315
October1st to 15thDay
13%12%30%29%11%2
294
16th to endDay
28%7%18%27%16%3
99
November1st to 15thDay
20%26%43%25%2
90
16th to endDay
25%6%34%23%6%2
89
December1st to 15thDay
45%11%23%15%31
60
16th to endDay
31%318%31%10%4
64
January1st to 15thNight
25%310%33%23%3
720
16th to endNight
23%210%31%26%5%
768
February1st to 15thNight
22%212%35%23%2
704
16th to endNight
20%5%15%34%20%3
632
March1st to 15thNight
22%5%15%34%18%3
720
16th to endNight
22%7%16%33%18%1
768
April1st to 15thNight
15%7%14%35%23%4
719
16th to endNight
13%5%20%39%19%2
558
May1st to 15thNight
9%5%18%38%24%3
540
16th to endNight
9%39%32%38%4
391
June1st to 15thNight
11%310%41%31%2
360
16th to endNight
426%45%37%2
360
July1st to 15thNight
21347%42%2
340
16th to endNight
26%46%41%2
376
August1st to 15thNight
426%43%38%4
494
16th to endNight
217%41%40%6%
675
September1st to 15thNight
31439%41%9%
720
16th to endNight
11%27%30%37%10%
716
October1st to 15thNight
11%39%38%30%6%
720
16th to endNight
16%29%36%28%5%
708
November1st to 15thNight
21%39%35%27%2
700
16th to endNight
21%216%34%19%6%
720
December1st to 15thNight
21%312%39%19%2
720
16th to endNight
27%314%34%15%3
768
Page generated at 2017-10-17 14:35:22. Version ac04

Copyright 2017 A. Danko


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