Castle Rock
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Castle Rock clear sky chart from 2005-11-05 to 2017-10-06.

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
55%
15984
27%
47083
19%
15942
63%
15942
41%
25921

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
54%
899
31%
2506
21%
895
63%
895
48%
1314
January16th to endNight
53%
807
33%
2535
24%
807
63%
807
42%
1317
February1st to 15thNight
46%
699
24%
2231
16%
698
56%
698
37%
1227
February16th to endNight
41%
632
33%
1894
17%
632
58%
632
42%
996
March1st to 15thNight
48%
720
26%
2124
14%
720
58%
720
41%
1169
March16th to endNight
45%
672
27%
2016
15%
672
58%
672
39%
1118
April1st to 15thNight
40%
539
23%
1798
15%
539
53%
539
34%
970
April16th to endNight
41%
540
21%
1800
16%
540
51%
540
28%
1074
May1st to 15thNight
50%
540
19%
1627
15%
540
56%
540
28%
1038
May16th to endNight
49%
562
17%
1498
10%
561
55%
561
35%
911
June1st to 15thNight
63%
540
22%
1440
16%
540
67%
540
47%
783
June16th to endNight
71%
540
25%
1440
20%
540
74%
540
50%
769
July1st to 15thNight
68%
510
16%
1360
14%
510
69%
510
34%
846
July16th to endNight
73%
564
21%
1443
19%
531
75%
531
38%
847
August1st to 15thNight
70%
539
17%
1686
18%
536
72%
536
32%
983
August16th to endNight
70%
573
25%
1910
26%
573
74%
573
38%
1029
September1st to 15thNight
66%
540
26%
1800
27%
540
71%
540
37%
974
September16th to endNight
67%
537
33%
1941
31%
537
75%
537
44%
920
October1st to 15thNight
55%
660
28%
2028
19%
660
62%
660
40%
1102
October16th to endNight
64%
736
35%
2144
22%
736
71%
736
50%
1093
November1st to 15thNight
60%
875
33%
2275
19%
875
66%
875
52%
1218
November16th to endNight
56%
900
35%
2379
22%
900
63%
900
52%
1259
December1st to 15thNight
51%
900
25%
2520
14%
900
59%
900
44%
1385
December16th to endNight
45%
960
27%
2688
15%
960
56%
960
37%
1579

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
5%42442446%8%52%
48133
Night
45%2432345%7%57%
47258
Cloud CoverDay
5%5%2442446%8%52%
48131
Night
45%2432335%7%57%
47258
TransparencyDay
28%6%12%22%20%8%
47810
Night
25%6%13%25%21%7%
47083
SeeingDay
10%8%29%28%18%5%
5903
Night
6%328%43%16%1
15991

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
16%23413247%63%
1432
16th to endDay
25%33322247%62%
1698
February1st to 15thDay
16%36%324346%55%
1630
16th to endDay
17%3332345%6%58%
1580
March1st to 15thDay
46%2442435%8%53%
1833
16th to endDay
5%8%2432346%9%49%
2208
April1st to 15thDay
7%6%25%31445%6%50%
2150
16th to endDay
10%7%244145%5%8%44%
2160
May1st to 15thDay
9%6%25%5%35%5%6%8%40%
2320
16th to endDay
8%413436%6%7%8%44%
2616
June1st to 15thDay
6%314325%5%7%9%49%
2520
16th to endDay
32124246%7%10%53%
2520
July1st to 15thDay
7%314425%6%9%10%43%
2520
16th to endDay
5%3245%37%6%7%10%43%
2626
August1st to 15thDay
6%325%5%36%5%8%9%43%
2265
16th to endDay
4313335%6%7%8%50%
2292
September1st to 15thDay
6%313425%5%5%7%53%
2160
16th to endDay
5%313322346%62%
2019
October1st to 15thDay
6%33323447%60%
1728
16th to endDay
5%412312245%65%
1716
November1st to 15thDay
241332335%8%61%
1583
16th to endDay
2424222347%64%
1581
December1st to 15thDay
16%25%42335%7%56%
1440
16th to endDay
25%25%424447%55%
1536
January1st to 15thNight
1324412347%64%
2506
16th to endNight
15%3442344462%
2535
February1st to 15thNight
27%35%423447%55%
2221
16th to endNight
27%34412346%59%
1894
March1st to 15thNight
45%2332346%6%57%
2124
16th to endNight
5%6%24313247%57%
2016
April1st to 15thNight
6%8%12324346%56%
1798
16th to endNight
14%8%14223345%49%
1800
May1st to 15thNight
13%5%243245%5%7%45%
1626
16th to endNight
7%5%1442436%9%51%
1497
June1st to 15thNight
5%2222335%11%59%
1440
16th to endNight
221222336%10%60%
1440
July1st to 15thNight
5%3145%35%5%7%8%48%
1440
16th to endNight
5%213435%5%7%11%48%
1541
August1st to 15thNight
4424425%6%6%9%49%
1695
16th to endNight
5%4124235%6%9%53%
1910
September1st to 15thNight
7%3134135%7%9%52%
1800
16th to endNight
5%212323336%64%
1941
October1st to 15thNight
6%5%2331335%5%59%
2028
16th to endNight
4413212347%63%
2144
November1st to 15thNight
2313323346%65%
2275
16th to endNight
25%23313236%64%
2379
December1st to 15thNight
25%24323348%58%
2520
16th to endNight
27%36%324447%55%
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
16%23412247%63%
1432
16th to endDay
25%3322225%7%62%
1698
February1st to 15thDay
16%36%323346%55%
1630
16th to endDay
17%2332345%6%58%
1580
March1st to 15thDay
46%3442435%8%53%
1833
16th to endDay
5%8%2432345%9%49%
2206
April1st to 15thDay
8%6%2432445%7%50%
2150
16th to endDay
9%8%244145%5%7%45%
2160
May1st to 15thDay
10%7%25%435%5%6%8%40%
2320
16th to endDay
9%413435%6%7%8%44%
2616
June1st to 15thDay
6%3133245%7%9%50%
2520
16th to endDay
3213425%6%6%10%53%
2520
July1st to 15thDay
7%324425%6%8%10%43%
2520
16th to endDay
5%4245%37%6%7%9%44%
2626
August1st to 15thDay
6%325%435%5%8%9%43%
2265
16th to endDay
5%313336%6%7%8%50%
2292
September1st to 15thDay
6%323425%5%5%6%54%
2160
16th to endDay
5%31332335%6%62%
2019
October1st to 15thDay
6%313323347%61%
1728
16th to endDay
5%412312235%65%
1716
November1st to 15thDay
141332335%7%61%
1583
16th to endDay
2423212347%64%
1581
December1st to 15thDay
16%25%42345%7%56%
1440
16th to endDay
25%35%423447%55%
1536
January1st to 15thNight
1325%312347%64%
2506
16th to endNight
15%3442334462%
2535
February1st to 15thNight
27%35%423447%55%
2221
16th to endNight
27%34413346%59%
1894
March1st to 15thNight
45%2332346%6%57%
2124
16th to endNight
5%6%14313248%57%
2016
April1st to 15thNight
6%7%12323346%56%
1798
16th to endNight
14%8%14223245%49%
1800
May1st to 15thNight
13%6%2432445%8%44%
1626
16th to endNight
7%6%2341336%8%52%
1497
June1st to 15thNight
5%21232345%11%59%
1440
16th to endNight
221232346%11%60%
1440
July1st to 15thNight
5%4145%35%5%7%8%48%
1440
16th to endNight
5%213435%5%7%10%48%
1541
August1st to 15thNight
4324325%5%7%9%49%
1695
16th to endNight
5%3134245%6%9%53%
1910
September1st to 15thNight
7%31341447%9%52%
1800
16th to endNight
5%213222336%64%
1941
October1st to 15thNight
6%5%1332335%5%59%
2028
16th to endNight
4412312346%63%
2144
November1st to 15thNight
2213323346%65%
2275
16th to endNight
25%23213236%64%
2379
December1st to 15thNight
25%2432335%7%58%
2520
16th to endNight
27%36%324446%54%
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
22%312%31%23%5%
1433
16th to endDay
22%311%31%22%9%
1698
February1st to 15thDay
29%413%32%15%4
1631
16th to endDay
24%6%10%26%25%6%
1580
March1st to 15thDay
28%411%25%21%8%
1833
16th to endDay
32%5%13%23%20%5%
2208
April1st to 15thDay
32%5%13%22%19%7%
2150
16th to endDay
36%7%13%20%17%3
2160
May1st to 15thDay
40%9%12%20%14%2
2320
16th to endDay
34%10%14%21%12%6%
2620
June1st to 15thDay
28%8%14%19%17%11%
2520
16th to endDay
22%7%12%19%25%11%
2520
July1st to 15thDay
31%10%13%17%15%10%
2371
16th to endDay
32%9%15%22%15%5%
2461
August1st to 15thDay
33%10%14%17%14%8%
2250
16th to endDay
27%7%13%21%23%6%
2292
September1st to 15thDay
28%5%12%20%19%13%
2160
16th to endDay
21%5%9%21%33%8%
2019
October1st to 15thDay
24%412%22%28%7%
1728
16th to endDay
21%39%25%29%10%
1716
November1st to 15thDay
21%5%11%23%24%14%
1583
16th to endDay
20%38%23%31%11%
1581
December1st to 15thDay
26%5%13%28%21%4
1440
16th to endDay
28%6%15%23%18%6%
1536
January1st to 15thNight
20%5%12%28%26%5%
2506
16th to endNight
24%410%27%23%9%
2535
February1st to 15thNight
28%5%13%30%17%4
2231
16th to endNight
25%38%29%23%8%
1894
March1st to 15thNight
25%6%11%23%26%6%
2124
16th to endNight
27%412%25%24%5%
2016
April1st to 15thNight
27%6%13%25%18%7%
1798
16th to endNight
36%5%12%24%16%4
1800
May1st to 15thNight
37%8%14%22%13%4
1627
16th to endNight
29%8%20%23%10%6%
1498
June1st to 15thNight
20%7%17%27%15%12%
1440
16th to endNight
17%8%12%24%26%10%
1440
July1st to 15thNight
31%9%17%20%13%8%
1360
16th to endNight
27%8%19%24%16%2
1443
August1st to 15thNight
29%10%17%23%14%6%
1686
16th to endNight
25%7%14%27%19%5%
1910
September1st to 15thNight
26%7%13%21%20%10%
1800
16th to endNight
21%411%26%29%6%
1941
October1st to 15thNight
26%5%13%20%25%8%
2028
16th to endNight
20%49%25%29%10%
2144
November1st to 15thNight
20%410%24%26%14%
2275
16th to endNight
21%39%23%31%10%
2379
December1st to 15thNight
24%5%15%29%19%5%
2520
16th to endNight
30%5%14%24%21%3
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%8%16%33%25%1
90
16th to endDay
4434%43%13%
96
February1st to 15thDay
27%54%30%5%
90
16th to endDay
412%35%27%18%1
81
March1st to 15thDay
216%39%32%8%1
123
16th to endDay
15%25%34%17%5%1
288
April1st to 15thDay
15%20%35%19%7%2
269
16th to endDay
18%23%34%15%5%
270
May1st to 15thDay
15%8%33%27%12%2
424
16th to endDay
16%11%25%24%17%4
517
June1st to 15thDay
7%6%28%28%21%7%
495
16th to endDay
5%5%27%29%25%7%
495
July1st to 15thDay
10%218%28%30%9%
475
16th to endDay
8%18%28%34%9%
485
August1st to 15thDay
11%327%33%17%7%
315
16th to endDay
7%228%37%18%6%
332
September1st to 15thDay
7%5%33%29%17%6%
315
16th to endDay
8%10%27%24%21%8%
174
October1st to 15thDay
48%26%30%18%11%
107
16th to endDay
7%330%32%19%7%
96
November1st to 15thDay
25%17%36%27%10%
90
16th to endDay
7%11%34%40%6%
90
December1st to 15thDay
8%10%46%27%6%
90
16th to endDay
45%45%35%8%1
96
January1st to 15thNight
3432%45%11%2
900
16th to endNight
2334%48%9%1
807
February1st to 15thNight
5%436%45%7%
704
16th to endNight
5%6%41%40%5%
632
March1st to 15thNight
5%338%41%10%
720
16th to endNight
8%7%35%41%7%
672
April1st to 15thNight
10%8%38%36%5%
539
16th to endNight
18%7%29%34%10%
540
May1st to 15thNight
15%424%41%12%
540
16th to endNight
10%330%38%15%1
563
June1st to 15thNight
5%223%48%18%2
540
16th to endNight
2119%50%25%
540
July1st to 15thNight
7%12%40%33%4
510
16th to endNight
5%11%42%37%2
564
August1st to 15thNight
6%12%45%32%2
539
16th to endNight
6%113%46%28%2
573
September1st to 15thNight
8%216%41%27%4
540
16th to endNight
6%120%44%24%2
537
October1st to 15thNight
8%230%39%15%2
660
16th to endNight
6%221%44%20%3
736
November1st to 15thNight
3427%46%16%1
875
16th to endNight
5%429%46%13%1
900
December1st to 15thNight
4335%47%9%
900
16th to endNight
6%437%41%8%1
960
Page generated at 2017-10-07 12:07:45. Version ac04

Copyright 2017 A. Danko


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