Star Valley
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Star Valley clear sky chart from 2005-11-05 to 2017-12-02.

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
51%
16019
17%
47542
15%
15976
53%
15976
26%
31163

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
38%
783
11%
2392
10%
781
40%
781
15%
1828
January16th to endNight
38%
768
13%
2496
12%
768
41%
768
16%
1836
February1st to 15thNight
35%
701
8%
2288
7%
698
37%
698
12%
1778
February16th to endNight
32%
632
10%
1974
9%
632
34%
632
14%
1490
March1st to 15thNight
41%
720
12%
2007
9%
720
44%
720
19%
1486
March16th to endNight
41%
768
12%
2112
8%
768
44%
768
20%
1549
April1st to 15thNight
42%
606
11%
1835
8%
606
45%
606
20%
1264
April16th to endNight
45%
540
18%
1620
14%
540
47%
540
26%
1040
May1st to 15thNight
53%
539
17%
1619
15%
539
54%
539
29%
988
May16th to endNight
56%
563
14%
1541
13%
561
58%
561
28%
1007
June1st to 15thNight
54%
510
14%
1410
11%
510
57%
510
32%
879
June16th to endNight
76%
360
29%
1260
33%
360
81%
360
54%
521
July1st to 15thNight
83%
384
23%
1267
26%
384
86%
384
53%
558
July16th to endNight
82%
564
28%
1593
29%
531
83%
531
60%
723
August1st to 15thNight
81%
539
28%
1611
26%
536
82%
536
51%
798
August16th to endNight
80%
573
38%
1734
34%
573
82%
573
56%
806
September1st to 15thNight
73%
621
29%
1881
27%
621
76%
621
48%
946
September16th to endNight
70%
716
31%
1980
25%
716
72%
716
44%
1101
October1st to 15thNight
56%
720
20%
2130
16%
720
58%
720
30%
1330
October16th to endNight
60%
768
26%
2317
22%
768
64%
768
34%
1376
November1st to 15thNight
44%
799
17%
2509
16%
799
47%
799
21%
1705
November16th to endNight
44%
975
15%
2730
11%
975
47%
975
23%
1911
December1st to 15thNight
29%
910
6%
2548
4%
910
31%
910
13%
2054
December16th to endNight
32%
960
8%
2688
6%
960
34%
960
12%
2189

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
9%11%46%5%24446%41%
48912
Night
9%12%45%423346%42%
47724
TransparencyDay
43%5%11%18%14%6%
48594
Night
43%5%12%20%13%5%
47543
SeeingDay
16%14%27%25%13%3
6096
Night
15%5%19%37%19%2
16026

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
9%22%7%8%5%3245%5%26%
1555
16th to endDay
8%23%5%8%32224432%
1728
February1st to 15thDay
12%22%7%8%5%24235%25%
1575
16th to endDay
9%22%9%12%6%3343421%
1500
March1st to 15thDay
9%16%6%9%5%3335%6%30%
1953
16th to endDay
10%19%7%8%5%3445%6%24%
2112
April1st to 15thDay
11%15%5%8%5%35%447%27%
2111
16th to endDay
11%15%47%6%34446%30%
2340
May1st to 15thDay
9%10%37%7%35%5%5%6%36%
2331
16th to endDay
14%9%47%7%46%5%5%6%28%
2573
June1st to 15thDay
11%6%25%5%3445%7%40%
2547
16th to endDay
3313313446%65%
2700
July1st to 15thDay
221332445%8%59%
2610
16th to endDay
3214424447%59%
2467
August1st to 15thDay
33145%25%5%5%7%54%
2340
16th to endDay
431342445%6%59%
2467
September1st to 15thDay
5%414424446%57%
2076
16th to endDay
10%424422245%57%
1980
October1st to 15thDay
13%9%35%5%2335%5%42%
1830
16th to endDay
12%9%24323437%44%
1905
November1st to 15thDay
13%15%5%6%322235%37%
1667
16th to endDay
12%15%6%8%223435%35%
1560
December1st to 15thDay
13%20%8%9%6%44235%22%
1449
16th to endDay
11%20%8%11%6%12335%22%
1536
January1st to 15thNight
11%20%5%7%5%23335%31%
2392
16th to endNight
9%22%6%7%5%1233433%
2496
February1st to 15thNight
10%22%5%8%5%23345%26%
2277
16th to endNight
9%19%8%9%425%34427%
1974
March1st to 15thNight
8%16%7%8%5%24446%31%
2007
16th to endNight
9%16%47%5%235%46%33%
2112
April1st to 15thNight
9%14%35%4345%5%7%35%
1835
16th to endNight
12%9%36%423346%43%
1620
May1st to 15thNight
9%6%35%42346%8%45%
1619
16th to endNight
11%6%25%5%2445%9%39%
1540
June1st to 15thNight
8%4245%345%6%9%45%
1410
16th to endNight
4112221235%72%
1260
July1st to 15thNight
12226%5%7%8%61%
1344
16th to endNight
12221445%7%67%
1701
August1st to 15thNight
22123235%6%10%58%
1620
16th to endNight
321221335%7%67%
1734
September1st to 15thNight
5%214222247%63%
1881
16th to endNight
9%413313335%60%
1980
October1st to 15thNight
12%8%24422335%48%
2130
16th to endNight
12%8%23223245%51%
2317
November1st to 15thNight
14%13%35%324345%37%
2509
16th to endNight
11%14%45%435%345%37%
2730
December1st to 15thNight
15%19%6%9%6%3323325%
2548
16th to endNight
13%21%6%10%6%3422423%
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
58%6%14%12%6%
1556
16th to endDay
55%5%13%17%7%1
1728
February1st to 15thDay
63%5%12%13%4
1575
16th to endDay
67%5%9%13%31
1500
March1st to 15thDay
54%6%16%16%5%
1953
16th to endDay
60%5%12%16%5%
2112
April1st to 15thDay
55%6%13%17%6%
2111
16th to endDay
53%410%22%8%
2340
May1st to 15thDay
46%5%9%25%12%
2331
16th to endDay
54%7%12%19%7%
2576
June1st to 15thDay
40%6%11%23%14%3
2547
16th to endDay
19%36%20%33%16%
2700
July1st to 15thDay
22%47%17%29%17%
2458
16th to endDay
22%46%12%26%27%
2312
August1st to 15thDay
25%5%9%15%24%19%
2325
16th to endDay
24%47%18%29%16%
2467
September1st to 15thDay
27%48%16%28%13%
2076
16th to endDay
31%39%25%26%4
1980
October1st to 15thDay
44%412%25%9%3
1830
16th to endDay
39%5%15%25%13%1
1905
November1st to 15thDay
51%312%20%9%2
1667
16th to endDay
52%5%17%16%6%1
1560
December1st to 15thDay
65%6%11%12%3
1449
16th to endDay
64%5%13%10%5%
1536
January1st to 15thNight
57%7%13%15%5%1
2392
16th to endNight
56%5%12%18%5%2
2496
February1st to 15thNight
60%7%11%15%5%
2288
16th to endNight
59%413%16%4
1974
March1st to 15thNight
53%6%13%19%6%
2007
16th to endNight
51%6%14%22%4
2112
April1st to 15thNight
46%6%17%19%7%1
1835
16th to endNight
41%416%26%10%
1620
May1st to 15thNight
34%7%12%32%12%
1620
16th to endNight
39%6%17%25%9%1
1541
June1st to 15thNight
34%7%14%26%15%2
1410
16th to endNight
15%36%22%36%15%
1260
July1st to 15thNight
16%39%24%27%18%
1267
16th to endNight
14%38%17%27%29%
1593
August1st to 15thNight
19%49%19%26%21%
1611
16th to endNight
16%37%21%31%20%
1734
September1st to 15thNight
22%38%17%33%14%
1881
16th to endNight
27%310%26%26%5%
1980
October1st to 15thNight
38%415%25%13%2
2130
16th to endNight
34%414%30%15%1
2317
November1st to 15thNight
48%412%22%9%2
2509
16th to endNight
48%5%16%20%8%1
2730
December1st to 15thNight
64%5%13%12%3
2548
16th to endNight
66%413%11%21
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
26%310%38%15%5%
90
16th to endDay
23%419%36%15%
96
February1st to 15thDay
34%11%15%22%14%2
90
16th to endDay
24%21%28%16%7%1
159
March1st to 15thDay
28%23%25%18%4
270
16th to endDay
24%28%30%12%2
288
April1st to 15thDay
24%23%29%14%6%1
269
16th to endDay
31%21%24%17%4
270
May1st to 15thDay
14%20%31%23%9%1
288
16th to endDay
19%12%22%25%17%3
474
June1st to 15thDay
13%11%27%27%15%3
495
16th to endDay
5%13%26%28%20%4
495
July1st to 15thDay
5%6%28%30%23%5%
439
16th to endDay
315%37%29%11%3
327
August1st to 15thDay
6%10%39%29%12%2
315
16th to endDay
5%12%27%31%15%6%
332
September1st to 15thDay
6%16%32%23%14%6%
315
16th to endDay
16%11%26%25%16%3
315
October1st to 15thDay
17%13%23%27%16%2
165
16th to endDay
21%10%17%28%17%4
144
November1st to 15thDay
24%5%20%22%14%12%
135
16th to endDay
28%5%25%31%8%1
135
December1st to 15thDay
34%10%17%32%32
94
16th to endDay
25%6%30%21%9%7%
96
January1st to 15thNight
20%7%22%33%12%1
786
16th to endNight
21%6%22%34%13%1
768
February1st to 15thNight
21%5%23%37%10%1
704
16th to endNight
18%8%30%32%9%
632
March1st to 15thNight
15%8%24%38%11%1
720
16th to endNight
16%9%24%36%12%
768
April1st to 15thNight
15%10%26%32%13%
606
16th to endNight
18%7%23%32%18%
540
May1st to 15thNight
13%5%20%38%21%
540
16th to endNight
15%415%36%26%2
563
June1st to 15thNight
11%6%21%38%21%
510
16th to endNight
5%113%45%30%2
360
July1st to 15thNight
227%45%40%1
384
16th to endNight
210%46%37%1
564
August1st to 15thNight
417%46%37%2
539
16th to endNight
417%44%37%2
573
September1st to 15thNight
7%211%40%33%4
621
16th to endNight
11%210%36%31%7%
716
October1st to 15thNight
16%316%38%21%3
720
16th to endNight
17%214%42%19%3
768
November1st to 15thNight
20%6%18%36%15%1
799
16th to endNight
18%8%22%34%12%2
975
December1st to 15thNight
25%6%25%34%7%
910
16th to endNight
22%10%21%33%9%2
960
Page generated at 2017-12-03 09:16:37. Version ac04

Copyright 2017 A. Danko


Star Valley Clear Sky Chart |Charts Home