Rocky Mountain Star Stare
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Rocky Mountain Star Stare clear sky chart from 2005-11-05 to 2017-10-31.

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
45%
16011
29%
47390
15%
15968
59%
15968
40%
24889

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
37%
879
31%
2485
15%
874
53%
874
48%
1200
January16th to endNight
34%
768
35%
2496
16%
768
56%
768
45%
1137
February1st to 15thNight
29%
699
27%
2217
10%
699
47%
699
38%
1133
February16th to endNight
25%
632
37%
1894
11%
632
52%
632
43%
928
March1st to 15thNight
35%
720
29%
2100
12%
720
50%
720
39%
1089
March16th to endNight
37%
684
33%
2028
14%
684
55%
684
40%
1023
April1st to 15thNight
29%
539
28%
1798
12%
539
51%
539
37%
860
April16th to endNight
35%
540
25%
1800
12%
540
52%
540
30%
963
May1st to 15thNight
38%
539
22%
1707
13%
539
51%
539
28%
1021
May16th to endNight
42%
563
23%
1498
9%
561
53%
561
36%
860
June1st to 15thNight
57%
540
24%
1440
16%
540
63%
540
44%
779
June16th to endNight
66%
540
22%
1440
15%
540
72%
540
44%
803
July1st to 15thNight
64%
510
16%
1360
12%
510
66%
510
29%
906
July16th to endNight
77%
564
15%
1509
15%
531
77%
531
29%
959
August1st to 15thNight
74%
539
14%
1702
14%
536
74%
536
27%
1045
August16th to endNight
70%
573
22%
1910
23%
573
73%
573
30%
1117
September1st to 15thNight
67%
540
24%
1800
23%
540
73%
540
32%
1014
September16th to endNight
61%
537
35%
1932
29%
537
72%
537
45%
886
October1st to 15thNight
52%
705
31%
2145
18%
705
63%
705
47%
1066
October16th to endNight
52%
768
38%
2304
19%
768
65%
768
49%
1120
November1st to 15thNight
48%
872
36%
2272
17%
872
59%
872
55%
1130
November16th to endNight
43%
900
38%
2345
16%
900
57%
900
54%
1171
December1st to 15thNight
30%
900
30%
2520
8%
900
48%
900
45%
1270
December16th to endNight
30%
960
30%
2688
10%
960
48%
960
41%
1409

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
34234245%6%8%54%
48369
Night
231332345%7%60%
47571
Cloud CoverDay
34244245%5%8%53%
48367
Night
242332345%7%59%
47571
TransparencyDay
24%7%12%23%22%8%
48052
Night
21%6%13%25%24%8%
47390
SeeingDay
7%15%29%26%15%4
5890
Night
5%10%32%31%16%2
16017

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
313322348%65%
1462
16th to endDay
323312346%68%
1728
February1st to 15thDay
435%413249%60%
1644
16th to endDay
41431336%8%61%
1580
March1st to 15thDay
14234245%5%8%57%
1857
16th to endDay
2424425%46%9%53%
2195
April1st to 15thDay
26%2432346%8%55%
2150
16th to endDay
48%35%435%5%6%7%47%
2160
May1st to 15thDay
6%7%25%435%5%6%8%44%
2241
16th to endDay
44234245%7%8%52%
2616
June1st to 15thDay
3212435%6%5%10%54%
2520
16th to endDay
1112335%6%8%8%56%
2520
July1st to 15thDay
5%4245%36%7%8%10%41%
2520
16th to endDay
3425%5%37%7%9%12%36%
2553
August1st to 15thDay
6%315%5%46%7%8%10%39%
2247
16th to endDay
5%5%245%35%6%6%10%45%
2292
September1st to 15thDay
5%414425%6%7%9%48%
2160
16th to endDay
332232345%6%65%
2028
October1st to 15thDay
4312323446%62%
1813
16th to endDay
2312221245%70%
1910
November1st to 15thDay
223212347%68%
1583
16th to endDay
31311235%7%68%
1614
December1st to 15thDay
1323223248%65%
1440
16th to endDay
1435%213349%60%
1536
January1st to 15thNight
212312247%68%
2485
16th to endNight
1213213346%69%
2496
February1st to 15thNight
1426%422345%62%
2207
16th to endNight
31431225%7%67%
1894
March1st to 15thNight
15%2321445%7%61%
2100
16th to endNight
2323212348%64%
2028
April1st to 15thNight
242321235%7%64%
1798
16th to endNight
48%24224348%55%
1800
May1st to 15thNight
6%7%233345%6%6%50%
1706
16th to endNight
6%42432435%8%55%
1497
June1st to 15thNight
22122245%6%8%61%
1440
16th to endNight
2113315%6%7%10%57%
1440
July1st to 15thNight
6%325%5%5%6%6%7%9%40%
1440
16th to endNight
4323437%8%9%11%40%
1613
August1st to 15thNight
23245%46%6%7%9%46%
1711
16th to endNight
6%3244247%8%9%45%
1910
September1st to 15thNight
6%423425%6%6%9%49%
1800
16th to endNight
431211345%6%64%
1932
October1st to 15thNight
3313222345%67%
2145
16th to endNight
2312212346%67%
2304
November1st to 15thNight
121221235%6%70%
2272
16th to endNight
1313211346%70%
2345
December1st to 15thNight
1213323348%65%
2520
16th to endNight
132431335%7%63%
2688

Percentage Cloud Cover SE (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
1314422347%63%
1462
16th to endDay
33332336%67%
1728
February1st to 15thDay
1435%423249%58%
1644
16th to endDay
42432435%8%60%
1580
March1st to 15thDay
14244245%5%8%55%
1857
16th to endDay
26%23425%5%5%9%52%
2193
April1st to 15thDay
26%2443345%9%53%
2150
16th to endDay
48%35%5%35%5%5%7%45%
2160
May1st to 15thDay
7%7%25%435%5%6%7%42%
2241
16th to endDay
4413425%5%7%9%50%
2616
June1st to 15thDay
3212435%6%6%10%52%
2520
16th to endDay
222326%6%7%9%55%
2520
July1st to 15thDay
5%425%6%36%7%8%10%39%
2520
16th to endDay
4425%6%37%8%9%11%35%
2553
August1st to 15thDay
6%4246%48%7%8%9%37%
2247
16th to endDay
6%5%245%45%5%6%9%44%
2292
September1st to 15thDay
6%4244345%5%9%48%
2160
16th to endDay
3313223346%64%
2028
October1st to 15thDay
4413323446%62%
1813
16th to endDay
2313212246%68%
1910
November1st to 15thDay
313212247%67%
1583
16th to endDay
323112437%67%
1614
December1st to 15thDay
333323248%63%
1440
16th to endDay
143432335%10%57%
1536
January1st to 15thNight
31231235%7%67%
2485
16th to endNight
1313214337%67%
2496
February1st to 15thNight
15%26%323336%61%
2207
16th to endNight
42421235%7%65%
1894
March1st to 15thNight
15%222145%5%7%60%
2100
16th to endNight
2323213348%63%
2028
April1st to 15thNight
15%2331235%7%63%
1798
16th to endNight
48%2342335%7%53%
1800
May1st to 15thNight
6%7%25%4245%6%6%48%
1706
16th to endNight
7%42442345%8%53%
1497
June1st to 15thNight
22123246%5%9%59%
1440
16th to endNight
2112226%5%7%9%56%
1440
July1st to 15thNight
7%426%6%37%5%7%8%40%
1440
16th to endNight
5%413437%8%9%11%39%
1613
August1st to 15thNight
33245%37%6%7%9%46%
1711
16th to endNight
6%3235%35%6%7%9%45%
1910
September1st to 15thNight
6%4133247%7%9%48%
1800
16th to endNight
4412213445%64%
1932
October1st to 15thNight
3312312345%66%
2145
16th to endNight
2313212436%67%
2304
November1st to 15thNight
121221235%6%69%
2272
16th to endNight
1313212247%69%
2345
December1st to 15thNight
131332235%8%63%
2520
16th to endNight
132431345%7%62%
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
17%414%33%24%5%
1463
16th to endDay
17%311%31%26%8%
1728
February1st to 15thDay
23%413%29%22%5%
1645
16th to endDay
19%5%10%27%30%7%
1580
March1st to 15thDay
23%5%10%24%27%8%
1857
16th to endDay
25%7%10%25%26%4
2195
April1st to 15thDay
24%6%11%27%20%9%
2150
16th to endDay
33%7%10%21%21%5%
2160
May1st to 15thDay
35%9%12%18%19%4
2241
16th to endDay
26%9%13%21%18%10%
2620
June1st to 15thDay
22%8%14%17%20%15%
2520
16th to endDay
19%7%13%19%25%14%
2520
July1st to 15thDay
33%12%14%18%14%7%
2371
16th to endDay
30%14%21%22%8%2
2394
August1st to 15thDay
34%13%18%15%12%6%
2232
16th to endDay
31%10%14%21%19%3
2292
September1st to 15thDay
28%8%14%23%16%7%
2160
16th to endDay
19%6%9%21%33%9%
2028
October1st to 15thDay
21%6%8%20%32%10%
1813
16th to endDay
15%5%7%26%34%9%
1910
November1st to 15thDay
15%410%25%30%13%
1583
16th to endDay
15%47%27%33%12%
1614
December1st to 15thDay
18%5%16%31%23%5%
1440
16th to endDay
21%6%18%28%18%6%
1536
January1st to 15thNight
16%415%30%29%5%
2485
16th to endNight
16%410%32%28%7%
2496
February1st to 15thNight
24%313%33%20%4
2217
16th to endNight
18%39%29%30%8%
1894
March1st to 15thNight
21%5%11%27%29%5%
2100
16th to endNight
19%5%10%28%31%5%
2028
April1st to 15thNight
20%412%29%24%8%
1798
16th to endNight
28%5%13%24%22%5%
1800
May1st to 15thNight
32%8%10%22%20%5%
1707
16th to endNight
26%6%15%23%16%10%
1498
June1st to 15thNight
19%7%14%20%19%18%
1440
16th to endNight
21%8%14%18%22%15%
1440
July1st to 15thNight
36%10%13%18%11%8%
1360
16th to endNight
28%15%20%22%9%2
1509
August1st to 15thNight
30%14%20%15%12%6%
1702
16th to endNight
29%11%15%23%15%4
1910
September1st to 15thNight
27%9%17%24%13%7%
1800
16th to endNight
18%5%11%23%31%9%
1932
October1st to 15thNight
19%411%20%31%11%
2145
16th to endNight
18%48%22%34%11%
2304
November1st to 15thNight
14%310%27%29%14%
2272
16th to endNight
15%37%28%33%11%
2345
December1st to 15thNight
17%5%14%33%22%5%
2520
16th to endNight
20%5%17%27%23%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
14%13%28%27%14%1
90
16th to endDay
318%38%22%16%
96
February1st to 15thDay
426%38%22%7%
90
16th to endDay
7%23%35%24%7%1
81
March1st to 15thDay
429%39%21%4
147
16th to endDay
10%39%35%12%2
288
April1st to 15thDay
8%36%34%13%41
269
16th to endDay
13%36%36%10%1
270
May1st to 15thDay
12%18%36%22%8%2
375
16th to endDay
9%15%31%26%13%3
517
June1st to 15thDay
415%27%27%20%5%
495
16th to endDay
37%28%31%23%6%
495
July1st to 15thDay
9%322%33%23%8%
475
16th to endDay
6%114%35%32%8%
412
August1st to 15thDay
7%423%36%20%7%
315
16th to endDay
10%423%39%17%3
332
September1st to 15thDay
5%11%35%26%15%5%
315
16th to endDay
6%13%38%25%12%3
183
October1st to 15thDay
420%26%28%13%6%
135
16th to endDay
6%13%29%29%16%4
144
November1st to 15thDay
314%22%33%23%3
90
16th to endDay
5%33%35%21%4
90
December1st to 15thDay
432%43%18%1
90
16th to endDay
7%19%40%28%4
96
January1st to 15thNight
116%40%27%10%2
879
16th to endNight
413%44%26%9%1
768
February1st to 15thNight
212%49%28%6%
704
16th to endNight
217%49%24%5%
632
March1st to 15thNight
417%39%28%9%
720
16th to endNight
318%38%32%6%
684
April1st to 15thNight
5%19%41%26%6%
539
16th to endNight
10%15%33%30%9%
540
May1st to 15thNight
10%8%35%33%11%1
540
16th to endNight
9%9%31%29%17%2
563
June1st to 15thNight
48%24%41%19%2
540
16th to endNight
4222%36%30%3
540
July1st to 15thNight
9%111%36%34%6%
510
16th to endNight
6%15%30%48%8%
564
August1st to 15thNight
417%33%46%6%
539
16th to endNight
7%19%33%41%6%
573
September1st to 15thNight
7%215%40%27%6%
540
16th to endNight
6%6%21%36%21%7%
537
October1st to 15thNight
5%6%31%36%15%4
705
16th to endNight
5%7%31%32%19%3
768
November1st to 15thNight
212%33%35%14%1
872
16th to endNight
5%12%37%32%11%1
900
December1st to 15thNight
313%48%25%8%
900
16th to endNight
315%45%25%8%
960
Page generated at 2017-11-01 15:23:42. Version ac04

Copyright 2017 A. Danko


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