Artist Point
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Artist Point clear sky chart from 2005-11-05 to 2018-01-12.

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
28%
14957
8%
48240
6%
14927
30%
14927
11%
38347

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
20%
801
9%
2828
6%
797
25%
797
8%
2366
January16th to endNight
21%
768
8%
2688
6%
768
24%
768
7%
2218
February1st to 15thNight
15%
700
5%
2302
3%
699
18%
699
7%
1979
February16th to endNight
17%
632
10%
2008
4%
632
25%
632
9%
1645
March1st to 15thNight
14%
720
2%
2097
1%
720
16%
720
6%
1852
March16th to endNight
13%
768
4%
2046
2%
768
15%
768
6%
1836
April1st to 15thNight
20%
719
4%
1799
2%
719
21%
719
8%
1587
April16th to endNight
24%
520
6%
1600
3%
520
26%
520
8%
1368
May1st to 15thNight
40%
360
10%
1440
15%
360
42%
360
12%
1055
May16th to endNight
41%
375
5%
1496
8%
374
42%
374
9%
1192
June1st to 15thNight
37%
360
2%
1308
2%
360
38%
360
11%
1023
June16th to endNight
44%
360
5%
1260
3%
360
45%
360
14%
924
July1st to 15thNight
62%
340
9%
1190
8%
340
64%
340
28%
697
July16th to endNight
67%
376
14%
1399
21%
354
70%
354
31%
732
August1st to 15thNight
70%
396
14%
1468
19%
394
72%
394
31%
771
August16th to endNight
58%
645
19%
1791
16%
645
59%
645
32%
1115
September1st to 15thNight
54%
720
19%
1800
10%
720
56%
720
35%
1169
September16th to endNight
39%
716
16%
1964
12%
716
41%
716
17%
1501
October1st to 15thNight
32%
720
10%
2160
8%
720
35%
720
15%
1616
October16th to endNight
21%
768
7%
2409
5%
768
25%
768
9%
1998
November1st to 15thNight
8%
760
3%
2636
1%
760
10%
760
3%
2404
November16th to endNight
15%
780
4%
2730
2%
780
17%
780
5%
2360
December1st to 15thNight
17%
780
8%
2730
3%
780
23%
780
8%
2216
December16th to endNight
7%
873
5%
3091
1%
873
12%
873
4%
2723

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
26%17%46%42333423%
49126
Night
25%17%45%42333424%
48396
Cloud CoverDay
25%18%45%42333423%
49126
Night
24%18%46%42333424%
48399
TransparencyDay
65%5%8%12%6%1
48786
Night
64%5%8%12%7%1
48240
SeeingDay
34%12%24%20%6%1
6254
Night
35%9%22%20%11%1
14961

By Month

Percentage Cloud Cover NW (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
33%19%5%5%42221416%
1352
16th to endDay
27%22%47%32232418%
1536
February1st to 15thDay
29%21%5%7%5%1323415%
1561
16th to endDay
18%30%8%6%41332317%
1466
March1st to 15thDay
31%29%7%6%3222129%
1862
16th to endDay
25%33%6%6%4232228%
2178
April1st to 15thDay
23%34%6%8%4232239%
2149
16th to endDay
24%29%46%5%2423411%
2357
May1st to 15thDay
21%19%36%5%34435%21%
2511
16th to endDay
32%14%46%5%2444415%
2615
June1st to 15thDay
37%13%36%5%2444314%
2650
16th to endDay
32%10%46%5%3433420%
2700
July1st to 15thDay
18%6%24323345%43%
2700
16th to endDay
16%7%2432434447%
2675
August1st to 15thDay
14%5%25%43435%6%43%
2483
16th to endDay
19%6%24323447%39%
2410
September1st to 15thDay
17%6%2442233448%
2160
16th to endDay
31%8%26%322345%30%
1995
October1st to 15thDay
30%10%25%334335%26%
1800
16th to endDay
39%13%35%32223320%
1815
November1st to 15thDay
44%23%25%2122229%
1549
16th to endDay
33%23%46%31233316%
1560
December1st to 15thDay
21%25%7%6%41232221%
1560
16th to endDay
26%35%6%6%31111113%
1482
January1st to 15thNight
36%18%4432223318%
2828
16th to endNight
25%23%46%423335%17%
2688
February1st to 15thNight
27%22%5%6%6%2332414%
2290
16th to endNight
20%26%5%6%42222320%
2008
March1st to 15thNight
29%26%5%5%42223413%
2097
16th to endNight
28%28%5%5%42331313%
2042
April1st to 15thNight
19%28%5%7%6%3433413%
1799
16th to endNight
26%21%46%43443416%
1600
May1st to 15thNight
21%12%25%5%33346%30%
1439
16th to endNight
26%10%36%5%35%5%5%6%21%
1496
June1st to 15thNight
29%10%36%5%33336%23%
1308
16th to endNight
24%8%26%42444430%
1260
July1st to 15thNight
12%5%2442334452%
1260
16th to endNight
11%313323346%56%
1494
August1st to 15thNight
9%41342235%6%56%
1476
16th to endNight
11%5%25%42445%6%47%
1791
September1st to 15thNight
13%5%2442233451%
1800
16th to endNight
28%7%35%5%2443431%
1964
October1st to 15thNight
25%9%25%433435%31%
2160
16th to endNight
35%12%35%6%3333418%
2409
November1st to 15thNight
41%20%36%5%222229%
2636
16th to endNight
32%24%45%42321315%
2730
December1st to 15thNight
24%21%5%5%32333320%
2730
16th to endNight
27%31%6%5%41212213%
3091

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
31%19%5%6%42312417%
1352
16th to endDay
25%23%5%5%32333418%
1536
February1st to 15thDay
26%23%5%7%42323414%
1561
16th to endDay
15%33%7%6%32432317%
1466
March1st to 15thDay
28%30%8%7%4132129%
1862
16th to endDay
23%34%6%6%5%232328%
2178
April1st to 15thDay
21%36%6%8%4231229%
2149
16th to endDay
23%29%5%7%43433411%
2357
May1st to 15thDay
20%19%45%5%25%435%22%
2511
16th to endDay
31%14%36%6%34445%15%
2615
June1st to 15thDay
39%11%35%5%2444414%
2650
16th to endDay
34%9%36%6%3333420%
2700
July1st to 15thDay
19%5%34424345%43%
2700
16th to endDay
16%6%23324345%47%
2675
August1st to 15thDay
14%5%15%5%2345%6%44%
2483
16th to endDay
19%6%2432445%6%39%
2410
September1st to 15thDay
17%6%1332333448%
2160
16th to endDay
30%9%24422345%30%
1995
October1st to 15thDay
30%9%345%24345%26%
1800
16th to endDay
36%15%25%42322419%
1815
November1st to 15thDay
41%25%343221329%
1549
16th to endDay
28%26%6%5%32222316%
1560
December1st to 15thDay
20%26%7%5%42223420%
1560
16th to endDay
25%33%8%7%3211114%
1482
January1st to 15thNight
33%20%45%31223417%
2827
16th to endNight
24%23%5%5%423336%17%
2688
February1st to 15thNight
25%24%5%6%5%3223414%
2290
16th to endNight
19%27%6%6%41222320%
2008
March1st to 15thNight
25%28%6%6%42233412%
2097
16th to endNight
25%28%7%5%42332313%
2046
April1st to 15thNight
17%31%47%6%2432414%
1799
16th to endNight
24%24%36%5%3443416%
1600
May1st to 15thNight
19%14%35%5%2435%6%29%
1439
16th to endNight
26%12%35%6%25%5%5%6%21%
1496
June1st to 15thNight
28%10%35%5%24337%23%
1308
16th to endNight
24%8%26%5%245%45%31%
1260
July1st to 15thNight
12%42432334453%
1260
16th to endNight
10%323314345%56%
1494
August1st to 15thNight
9%41241335%6%56%
1476
16th to endNight
11%6%35%323447%47%
1791
September1st to 15thNight
13%6%2442343451%
1800
16th to endNight
27%7%27%43444430%
1964
October1st to 15thNight
25%9%26%5%23445%30%
2160
16th to endNight
33%14%26%6%3323418%
2409
November1st to 15thNight
38%22%36%5%233228%
2636
16th to endNight
28%25%5%7%42322214%
2730
December1st to 15thNight
23%21%5%6%32433420%
2730
16th to endNight
25%31%7%7%32222212%
3091

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
73%35%9%5%1
1352
16th to endDay
69%6%6%8%7%2
1536
February1st to 15thDay
73%6%5%7%5%1
1561
16th to endDay
73%46%9%41
1466
March1st to 15thDay
83%445%1
1862
16th to endDay
83%45%5%
2178
April1st to 15thDay
83%35%5%1
2149
16th to endDay
78%5%8%5%2
2357
May1st to 15thDay
65%6%10%12%5%
2511
16th to endDay
71%7%10%8%1
2619
June1st to 15thDay
73%6%8%8%3
2650
16th to endDay
68%5%8%15%2
2700
July1st to 15thDay
43%6%9%24%13%1
2541
16th to endDay
38%6%10%28%14%2
2507
August1st to 15thDay
39%8%14%24%10%2
2466
16th to endDay
43%8%12%25%8%1
2410
September1st to 15thDay
39%5%9%22%20%2
2160
16th to endDay
58%5%9%13%10%2
1995
October1st to 15thDay
60%6%9%15%7%
1800
16th to endDay
70%37%11%6%
1815
November1st to 15thDay
83%345%21
1549
16th to endDay
74%446%6%2
1560
December1st to 15thDay
69%5%5%9%7%1
1560
16th to endDay
81%2346%1
1482
January1st to 15thNight
72%4310%5%2
2828
16th to endNight
70%5%5%8%6%3
2688
February1st to 15thNight
74%5%6%6%42
2302
16th to endNight
69%46%13%41
2008
March1st to 15thNight
76%6%7%7%2
2097
16th to endNight
78%5%6%7%1
2046
April1st to 15thNight
75%49%7%2
1799
16th to endNight
70%7%9%9%3
1600
May1st to 15thNight
55%8%12%15%6%
1440
16th to endNight
61%10%12%11%3
1496
June1st to 15thNight
62%7%13%12%4
1308
16th to endNight
54%8%14%17%4
1260
July1st to 15thNight
35%6%13%25%15%2
1190
16th to endNight
28%7%14%27%17%4
1399
August1st to 15thNight
28%7%19%26%14%3
1468
16th to endNight
36%5%16%27%11%2
1791
September1st to 15thNight
35%6%11%20%21%3
1800
16th to endNight
56%6%7%15%9%3
1964
October1st to 15thNight
56%6%10%16%10%
2160
16th to endNight
69%5%6%10%7%
2409
November1st to 15thNight
82%43422
2636
16th to endNight
76%445%6%2
2730
December1st to 15thNight
68%5%8%8%7%1
2730
16th to endNight
79%335%5%1
3091

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
18%9%23%24%21%2
82
16th to endDay
48%17%9%18%6%
64
February1st to 15thDay
45%14%22%13%3
221
16th to endDay
38%15%22%18%5%
219
March1st to 15thDay
54%18%19%6%1
270
16th to endDay
45%22%19%9%2
288
April1st to 15thDay
46%15%17%13%5%1
269
16th to endDay
41%18%19%12%5%2
270
May1st to 15thDay
29%15%27%18%7%1
288
16th to endDay
38%9%19%19%10%3
330
June1st to 15thDay
37%10%21%23%6%
445
16th to endDay
30%12%27%22%6%1
495
July1st to 15thDay
21%8%28%33%6%1
475
16th to endDay
20%8%34%27%5%4
344
August1st to 15thDay
17%6%28%29%13%4
315
16th to endDay
19%7%31%29%8%3
332
September1st to 15thDay
25%13%23%26%9%1
315
16th to endDay
32%11%26%18%9%2
315
October1st to 15thDay
38%13%25%15%41
315
16th to endDay
46%7%21%18%5%
231
November1st to 15thDay
61%14%16%5%11
95
16th to endDay
53%10%17%7%37%
90
December1st to 15thDay
37%12%16%13%20%
90
16th to endDay
34%13%35%12%4
96
January1st to 15thNight
45%10%19%17%7%
801
16th to endNight
38%11%24%16%7%1
768
February1st to 15thNight
40%8%28%17%4
704
16th to endNight
35%12%29%16%5%
632
March1st to 15thNight
41%15%24%11%6%
720
16th to endNight
41%16%24%12%4
768
April1st to 15thNight
36%12%21%18%7%2
719
16th to endNight
38%6%24%20%8%2
520
May1st to 15thNight
26%6%20%29%13%3
360
16th to endNight
33%215%27%20%
375
June1st to 15thNight
29%6%18%26%18%1
360
16th to endNight
24%320%31%18%1
360
July1st to 15thNight
14%216%31%32%2
340
16th to endNight
11%212%36%33%2
376
August1st to 15thNight
12%11%34%37%4
396
16th to endNight
15%216%32%29%2
645
September1st to 15thNight
17%222%25%28%3
720
16th to endNight
31%5%18%26%15%2
716
October1st to 15thNight
32%6%22%24%12%
720
16th to endNight
43%7%23%17%5%1
768
November1st to 15thNight
52%13%20%11%2
760
16th to endNight
46%12%22%10%6%1
780
December1st to 15thNight
37%10%30%17%3
780
16th to endNight
42%18%27%9%1
873
Page generated at 2018-01-12 19:01:31. Version ac04

Copyright 2018 A. Danko


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