Shot Rock
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Shot Rock clear sky chart from 2005-11-06 to 2024-01-15.

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%
23464
29%
74663
20%
23419
62%
23419
36%
40225

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 10thNight
35%
757
21%
2646
13%
756
47%
756
22%
1590
January11th to 20thNight
36%
736
24%
2490
14%
736
51%
736
24%
1479
January21st to endNight
37%
792
27%
2574
16%
792
52%
792
22%
1580
February1st to 10thNight
36%
720
25%
2339
16%
720
50%
720
25%
1379
February11th to 20thNight
40%
700
28%
2098
18%
700
52%
700
27%
1253
February21st to endNight
36%
592
25%
1776
15%
592
50%
592
25%
1115
March1st to 10thNight
31%
720
17%
2160
9%
720
43%
720
21%
1456
March11th to 20thNight
39%
720
21%
1986
13%
720
47%
720
26%
1287
March21st to endNight
34%
792
19%
2052
7%
792
44%
792
26%
1378
April1st to 10thNight
41%
720
22%
1800
8%
720
49%
720
31%
1171
April11th to 20thNight
41%
711
25%
1779
8%
711
50%
711
35%
1121
April21st to endNight
49%
720
26%
1800
10%
720
56%
720
42%
1059
May1st to 10thNight
49%
651
26%
1731
12%
651
57%
651
42%
961
May11th to 20thNight
59%
400
31%
1462
26%
400
67%
400
41%
672
May21st to endNight
58%
388
24%
1552
22%
388
67%
388
36%
721
June1st to 10thNight
63%
360
28%
1440
29%
360
72%
360
40%
640
June11th to 20thNight
66%
360
37%
1440
36%
360
82%
360
60%
502
June21st to endNight
71%
360
35%
1440
38%
360
83%
360
58%
509
July1st to 10thNight
82%
350
37%
1400
44%
350
88%
350
73%
436
July11th to 20thNight
77%
348
37%
1392
42%
348
83%
348
62%
487
July21st to endNight
79%
504
39%
1592
35%
476
83%
476
58%
668
August1st to 10thNight
76%
558
36%
1623
27%
555
79%
555
62%
747
August11th to 20thNight
75%
712
36%
1780
19%
712
79%
712
70%
865
August21st to endNight
79%
792
42%
1980
25%
792
82%
792
76%
916
September1st to 10thNight
78%
720
46%
1800
27%
720
84%
720
81%
803
September11th to 20thNight
71%
720
45%
1818
29%
720
80%
720
70%
861
September21st to endNight
63%
720
42%
1980
28%
720
77%
720
62%
919
October1st to 10thNight
58%
720
33%
2142
25%
720
71%
720
49%
1053
October11th to 20thNight
59%
720
39%
2160
31%
720
73%
720
51%
1002
October21st to endNight
57%
792
40%
2390
31%
792
72%
792
52%
1102
November1st to 10thNight
57%
740
30%
2405
26%
740
66%
740
36%
1289
November11th to 20thNight
46%
760
32%
2470
22%
760
63%
760
36%
1291
November21st to endNight
41%
760
31%
2517
21%
760
55%
760
31%
1376
December1st to 10thNight
38%
760
26%
2660
15%
760
53%
760
25%
1519
December11th to 20thNight
35%
760
21%
3219
15%
759
49%
759
15%
2190
December21st to endNight
29%
829
16%
4770
13%
817
44%
817
11%
2828

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
7%7%24323345%59%
74783
Night
7%8%34323446%58%
75003
TransparencyDay
27%38%20%25%17%
74494
Night
28%47%19%25%17%
74813
SeeingDay
16%17%33%22%10%3
13995
Night
13%9%22%33%20%4
23479

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 10thDay
12%12%35%42446%6%42%
1519
11th to 20thDay
8%12%35%333346%50%
1555
21st to endDay
10%15%443245%5%8%41%
1782
February1st to 10thDay
11%10%36%324337%48%
1620
11th to 20thDay
7%12%5%5%333447%47%
1750
21st to endDay
9%14%7%7%424335%42%
1480
March1st to 10thDay
8%17%7%8%434446%34%
1800
11th to 20thDay
10%17%5%5%42445%7%37%
1970
21st to endDay
10%18%5%6%423347%39%
2304
April1st to 10thDay
10%13%45%32345%6%44%
2160
11th to 20thDay
9%12%35%323346%49%
2129
21st to endDay
9%9%2331345%7%55%
2160
May1st to 10thDay
8%8%3332235%7%57%
2227
11th to 20thDay
7%9%24423347%55%
2428
21st to endDay
11%9%2442345%6%50%
2723
June1st to 10thDay
6%5%2432435%6%60%
2520
11th to 20thDay
3312222235%75%
2520
21st to endDay
321221333477%
2520
July1st to 10thDay
11111222385%
2520
11th to 20thDay
211221223480%
2520
21st to endDay
231222234476%
2629
August1st to 10thDay
221222233477%
2305
11th to 20thDay
11222233480%
2122
21st to endDay
211111222385%
2376
September1st to 10thDay
21121223383%
2160
11th to 20thDay
421232334472%
2142
21st to endDay
5%41221223474%
1980
October1st to 10thDay
7%423323446%63%
1814
11th to 20thDay
6%21232234469%
1800
21st to endDay
6%5%13323436%65%
1964
November1st to 10thDay
8%9%3333335%6%53%
1674
11th to 20thDay
7%7%2342445%6%56%
1710
21st to endDay
7%8%3432346%6%54%
1658
December1st to 10thDay
12%8%25%425%446%49%
1520
11th to 20thDay
15%13%5%8%5%3435%5%33%
1928
21st to endDay
8%10%45%5%346%6%9%41%
2794
January1st to 10thNight
11%12%345%2345%7%43%
2646
11th to 20thNight
8%10%35%4345%6%7%45%
2490
21st to endNight
10%12%3443445%6%45%
2574
February1st to 10thNight
10%9%35%423447%49%
2339
11th to 20thNight
6%12%5%5%42446%7%45%
2098
21st to endNight
9%11%5%8%32333447%
1776
March1st to 10thNight
9%16%6%8%423446%40%
2160
11th to 20thNight
10%12%45%4235%5%8%42%
1986
21st to endNight
9%13%45%43445%6%43%
2052
April1st to 10thNight
9%10%45%424447%46%
1800
11th to 20thNight
7%10%45%323447%51%
1779
21st to endNight
6%8%23224448%57%
1800
May1st to 10thNight
5%6%2442345%6%59%
1731
11th to 20thNight
47%2232345%8%60%
1462
21st to endNight
7%7%23213448%59%
1552
June1st to 10thNight
6%5%12324335%66%
1440
11th to 20thNight
22121223381%
1440
21st to endNight
311221223380%
1440
July1st to 10thNight
11221222286%
1440
11th to 20thNight
221221222480%
1440
21st to endNight
321232233474%
1686
August1st to 10thNight
332322333375%
1632
11th to 20thNight
211221234378%
1780
21st to endNight
221121122384%
1980
September1st to 10thNight
12111112486%
1800
11th to 20thNight
321112225%79%
1818
21st to endNight
3212322325%75%
1980
October1st to 10thNight
5%41231333470%
2142
11th to 20thNight
5%313222445%71%
2160
21st to endNight
5%411222346%71%
2390
November1st to 10thNight
8%8%33323347%56%
2405
11th to 20thNight
6%5%1343445%8%57%
2470
21st to endNight
7%8%34433446%55%
2517
December1st to 10thNight
12%9%34324446%49%
2660
11th to 20thNight
14%16%36%5%35%45%7%33%
3276
21st to endNight
9%11%5%7%6%35%5%5%7%38%
4862

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 10thDay
42%5%10%21%17%6%
1519
11th to 20thDay
36%38%20%21%12%
1555
21st to endDay
42%47%17%20%10%
1782
February1st to 10thDay
38%39%19%18%12%
1620
11th to 20thDay
38%47%19%23%9%
1760
21st to endDay
47%36%20%18%6%
1480
March1st to 10thDay
52%48%17%13%5%
1800
11th to 20thDay
46%49%18%18%6%
1970
21st to endDay
46%5%13%20%12%3
2304
April1st to 10thDay
40%5%13%20%18%4
2160
11th to 20thDay
37%5%11%23%18%7%
2132
21st to endDay
29%415%29%19%3
2160
May1st to 10thDay
27%412%30%22%4
2227
11th to 20thDay
30%411%29%22%4
2431
21st to endDay
35%5%12%28%16%4
2724
June1st to 10thDay
25%411%26%27%7%
2520
11th to 20thDay
13%39%25%33%17%
2520
21st to endDay
12%3317%36%29%
2520
July1st to 10thDay
7%2312%31%46%
2451
11th to 20thDay
9%2417%27%41%
2445
21st to endDay
12%2413%29%40%
2483
August1st to 10thDay
12%2415%29%38%
2289
11th to 20thDay
9%3312%40%34%
2122
21st to endDay
8%1214%39%35%
2376
September1st to 10thDay
9%1211%37%39%
2160
11th to 20thDay
16%3423%36%18%
2142
21st to endDay
17%2422%36%19%
1980
October1st to 10thDay
23%36%17%30%22%
1814
11th to 20thDay
19%36%23%28%21%
1800
21st to endDay
21%37%20%30%19%
1964
November1st to 10thDay
33%37%22%23%13%
1674
11th to 20thDay
29%49%19%26%13%
1710
21st to endDay
30%47%20%26%12%
1658
December1st to 10thDay
36%5%8%19%20%12%
1520
11th to 20thDay
54%45%14%15%9%
1928
21st to endDay
38%5%11%21%17%8%
2794
January1st to 10thNight
39%5%9%22%18%8%
2646
11th to 20thNight
37%5%7%16%22%13%
2490
21st to endNight
40%46%15%21%14%
2574
February1st to 10thNight
37%47%18%20%15%
2339
11th to 20thNight
35%48%20%22%11%
2099
21st to endNight
40%46%21%21%8%
1776
March1st to 10thNight
47%49%15%19%6%
2160
11th to 20thNight
40%5%9%19%19%8%
1986
21st to endNight
41%6%11%22%16%5%
2052
April1st to 10thNight
37%5%12%21%18%6%
1800
11th to 20thNight
32%6%12%22%19%8%
1779
21st to endNight
26%5%11%35%19%4
1800
May1st to 10thNight
25%5%11%28%26%6%
1731
11th to 20thNight
22%311%33%26%5%
1462
21st to endNight
23%6%16%30%21%5%
1552
June1st to 10thNight
22%410%24%30%9%
1440
11th to 20thNight
9%36%29%33%19%
1440
21st to endNight
12%2316%34%33%
1440
July1st to 10thNight
7%1311%32%46%
1400
11th to 20thNight
10%3413%27%43%
1392
21st to endNight
15%2412%25%42%
1592
August1st to 10thNight
14%3314%28%38%
1623
11th to 20thNight
11%3313%34%37%
1780
21st to endNight
9%1212%35%40%
1980
September1st to 10thNight
6%1211%37%42%
1800
11th to 20thNight
11%2424%38%21%
1818
21st to endNight
13%3324%34%22%
1980
October1st to 10thNight
19%45%19%31%22%
2142
11th to 20thNight
17%35%19%34%22%
2160
21st to endNight
16%37%21%34%20%
2390
November1st to 10thNight
28%47%21%23%16%
2405
11th to 20thNight
26%5%7%20%29%13%
2470
21st to endNight
31%45%21%26%14%
2517
December1st to 10thNight
36%37%17%22%14%
2660
11th to 20thNight
50%5%5%13%19%9%
3276
21st to endNight
44%5%8%15%19%8%
4862

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 10thDay
37%17%23%17%6%1
180
11th to 20thDay
27%14%27%18%10%4
251
21st to endDay
24%17%23%21%12%2
374
February1st to 10thDay
29%16%24%18%9%3
340
11th to 20thDay
23%21%30%18%7%1
415
21st to endDay
24%23%31%16%41
346
March1st to 10thDay
32%24%24%14%42
420
11th to 20thDay
29%21%23%15%10%1
420
21st to endDay
29%23%29%15%5%
462
April1st to 10thDay
21%23%31%17%7%1
420
11th to 20thDay
30%20%26%17%5%1
412
21st to endDay
18%19%29%21%9%4
420
May1st to 10thDay
21%19%30%19%8%3
423
11th to 20thDay
21%20%27%19%11%3
448
21st to endDay
21%15%24%21%14%4
485
June1st to 10thDay
13%17%35%19%11%5%
450
11th to 20thDay
11%22%34%20%9%4
450
21st to endDay
417%37%26%10%5%
450
July1st to 10thDay
211%52%20%11%4
446
11th to 20thDay
211%45%27%12%5%
444
21st to endDay
310%44%25%13%6%
487
August1st to 10thDay
415%42%23%12%4
447
11th to 20thDay
312%42%26%11%6%
437
21st to endDay
49%47%26%12%2
495
September1st to 10thDay
412%44%24%14%2
450
11th to 20thDay
9%17%36%27%9%2
450
21st to endDay
10%14%36%32%5%2
450
October1st to 10thDay
10%20%28%32%8%2
450
11th to 20thDay
10%13%32%29%12%3
450
21st to endDay
14%16%29%26%12%4
479
November1st to 10thDay
20%14%21%24%17%5%
270
11th to 20thDay
15%12%29%25%13%7%
270
21st to endDay
16%14%30%22%15%3
246
December1st to 10thDay
23%14%22%20%13%7%
180
11th to 20thDay
19%22%27%15%14%3
180
21st to endDay
27%13%26%20%12%2
198
January1st to 10thNight
21%13%24%23%14%6%
760
11th to 20thNight
18%13%28%28%10%3
736
21st to endNight
19%14%24%25%15%4
792
February1st to 10thNight
18%15%23%25%16%3
720
11th to 20thNight
18%13%23%27%14%5%
704
21st to endNight
22%11%24%29%11%2
592
March1st to 10thNight
23%13%27%24%11%2
720
11th to 20thNight
19%11%25%22%19%3
720
21st to endNight
19%13%28%28%11%1
792
April1st to 10thNight
16%10%26%33%13%2
720
11th to 20thNight
14%13%26%30%14%4
711
21st to endNight
13%10%24%30%19%4
720
May1st to 10thNight
10%11%25%32%19%3
651
11th to 20thNight
6%10%19%40%23%3
400
21st to endNight
11%421%33%27%4
389
June1st to 10thNight
8%420%40%23%4
360
11th to 20thNight
35%23%42%25%2
360
21st to endNight
4417%44%29%2
360
July1st to 10thNight
112%46%37%3
350
11th to 20thNight
2214%45%34%3
348
21st to endNight
4111%33%44%8%
504
August1st to 10thNight
4115%45%31%4
558
11th to 20thNight
2217%45%29%5%
712
21st to endNight
2214%49%31%3
792
September1st to 10thNight
3215%46%30%4
720
11th to 20thNight
4320%36%29%8%
720
21st to endNight
46%23%34%25%8%
720
October1st to 10thNight
9%8%21%37%20%6%
720
11th to 20thNight
8%9%20%36%22%5%
720
21st to endNight
11%8%22%29%21%9%
792
November1st to 10thNight
13%9%18%34%20%6%
740
11th to 20thNight
12%10%27%31%15%4
760
21st to endNight
15%13%26%28%15%3
760
December1st to 10thNight
21%11%25%28%12%3
760
11th to 20thNight
22%12%24%27%12%3
760
21st to endNight
24%15%24%25%10%2
836
Page generated at 2024-01-11 19:33:52. Version ac07

Copyright 2024 Attilla Danko


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