Divide
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Divide clear sky chart from 2005-11-06 to 2024-03-23.

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
39%
24784
27%
80110
12%
24677
53%
24677
33%
42028

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
30%
943
31%
4328
11%
926
50%
926
23%
2007
January11th to 20thNight
26%
878
38%
4132
12%
858
48%
858
28%
1539
January21st to endNight
29%
829
22%
4278
12%
814
52%
814
24%
2008
February1st to 10thNight
17%
760
30%
2470
7%
760
43%
760
31%
1227
February11th to 20thNight
20%
743
29%
2223
6%
740
43%
740
31%
1185
February21st to endNight
19%
628
35%
1884
6%
628
49%
628
33%
950
March1st to 10thNight
25%
760
29%
2280
7%
760
44%
760
33%
1180
March11th to 20thNight
34%
760
26%
2103
11%
760
45%
760
35%
1232
March21st to endNight
24%
671
29%
2071
6%
671
47%
671
30%
1149
April1st to 10thNight
25%
540
26%
1800
8%
540
47%
540
29%
938
April11th to 20thNight
26%
533
23%
1777
9%
533
45%
533
26%
999
April21st to endNight
28%
540
22%
1800
9%
540
47%
540
26%
1053
May1st to 10thNight
36%
540
20%
1720
13%
540
46%
540
27%
1022
May11th to 20thNight
45%
531
14%
1451
10%
531
50%
531
28%
953
May21st to endNight
39%
583
18%
1552
8%
582
49%
582
31%
956
June1st to 10thNight
57%
540
21%
1440
15%
540
62%
540
40%
817
June11th to 20thNight
55%
540
24%
1440
14%
540
62%
540
45%
775
June21st to endNight
63%
540
22%
1440
18%
540
66%
540
39%
840
July1st to 10thNight
62%
525
16%
1400
15%
525
65%
525
31%
911
July11th to 20thNight
67%
522
23%
1392
19%
522
69%
522
40%
816
July21st to endNight
70%
591
13%
1573
12%
558
72%
558
25%
1048
August1st to 10thNight
66%
537
13%
1616
12%
534
67%
534
25%
1018
August11th to 20thNight
65%
534
22%
1778
23%
534
69%
534
31%
1006
August21st to endNight
66%
594
22%
1980
22%
594
70%
594
34%
1108
September1st to 10thNight
63%
540
26%
1800
23%
540
71%
540
33%
981
September11th to 20thNight
61%
540
34%
1818
28%
540
70%
540
42%
901
September21st to endNight
53%
540
30%
1980
23%
540
65%
540
38%
958
October1st to 10thNight
46%
702
28%
2142
12%
702
59%
702
40%
1131
October11th to 20thNight
45%
720
37%
2160
15%
720
62%
720
52%
992
October21st to endNight
40%
815
36%
2399
14%
815
56%
815
42%
1247
November1st to 10thNight
38%
925
34%
2405
12%
925
52%
925
50%
1211
November11th to 20thNight
31%
950
36%
2470
11%
950
49%
950
44%
1284
November21st to endNight
34%
950
32%
2531
11%
950
50%
950
42%
1347
December1st to 10thNight
29%
950
29%
2660
9%
950
46%
950
34%
1368
December11th to 20thNight
22%
949
28%
3126
7%
949
42%
949
30%
1624
December21st to endNight
20%
1041
19%
4691
7%
1026
40%
1026
20%
2247

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
46%36%5%35%5%6%8%49%
78806
Night
25%25%5%345%6%8%56%
81133
TransparencyDay
30%7%12%22%21%8%
78516
Night
24%7%13%25%23%8%
80945
SeeingDay
11%19%31%24%12%3
14582
Night
6%16%34%30%13%2
24805

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
326%7%245%5%8%57%
2538
11th to 20thDay
1326%6%45%5%6%7%55%
2681
21st to endDay
7%48%5%3445%6%54%
3146
February1st to 10thDay
6%48%5%2345%8%56%
1710
11th to 20thDay
1325%4335%6%10%59%
1841
21st to endDay
7%36%5%2435%7%59%
1570
March1st to 10thDay
26%36%5%3445%8%53%
1900
11th to 20thDay
38%47%6%3446%8%46%
2075
21st to endDay
29%48%5%35%5%6%9%45%
2329
April1st to 10thDay
38%36%6%45%5%6%9%47%
2160
11th to 20thDay
5%9%48%6%35%46%6%43%
2131
21st to endDay
5%12%48%7%35%5%5%7%39%
2160
May1st to 10thDay
7%10%36%6%46%6%7%8%35%
2240
11th to 20thDay
7%10%48%5%36%6%7%8%35%
2441
21st to endDay
5%6%35%5%37%6%7%8%44%
2724
June1st to 10thDay
5%5%35%5%46%6%8%9%45%
2520
11th to 20thDay
5%425%5%35%6%7%8%51%
2520
21st to endDay
35%26%6%47%6%7%9%44%
2520
July1st to 10thDay
7%426%6%6%7%7%7%8%40%
2520
11th to 20thDay
6%5%36%7%5%6%7%8%9%40%
2520
21st to endDay
8%8%37%8%5%7%7%8%9%30%
2649
August1st to 10thDay
9%7%37%6%5%7%7%7%8%33%
2311
11th to 20thDay
5%5%25%6%46%7%7%9%43%
2123
21st to endDay
6%5%37%6%36%5%7%8%44%
2376
September1st to 10thDay
6%6%35%6%35%5%5%6%49%
2160
11th to 20thDay
6%4245%35%45%5%55%
2142
21st to endDay
5%42442345%7%61%
1980
October1st to 10thDay
45%24435%46%7%56%
1814
11th to 20thDay
3323223446%67%
1800
21st to endDay
48%24423445%61%
1936
November1st to 10thDay
142422345%7%66%
1673
11th to 20thDay
15%2333335%8%64%
1710
21st to endDay
15%35%4245%5%7%60%
1646
December1st to 10thDay
425%42445%10%59%
1520
11th to 20thDay
1435%4335%5%10%57%
1926
21st to endDay
437%7%345%5%8%54%
2794
January1st to 10thNight
439%7%3445%8%55%
4417
11th to 20thNight
12135%245%5%8%64%
4306
21st to endNight
5%37%5%3445%7%58%
4521
February1st to 10thNight
5%36%5%2345%8%59%
2470
11th to 20thNight
426%5%2445%8%59%
2223
21st to endNight
5%34423346%65%
1884
March1st to 10thNight
15%25%43447%8%58%
2280
11th to 20thNight
37%35%5%2445%9%54%
2103
21st to endNight
27%35%5%3445%7%55%
2071
April1st to 10thNight
37%25%42435%6%59%
1800
11th to 20thNight
39%36%43445%8%51%
1777
21st to endNight
5%10%36%423449%49%
1800
May1st to 10thNight
6%8%36%5%25%5%6%8%46%
1720
11th to 20thNight
5%10%26%4346%7%9%43%
1451
21st to endNight
5%6%35%5%35%5%6%9%49%
1552
June1st to 10thNight
3415%336%5%7%10%52%
1440
11th to 20thNight
3212425%7%9%9%57%
1440
21st to endNight
34135%37%6%7%9%52%
1440
July1st to 10thNight
5%436%6%46%7%7%10%42%
1440
11th to 20thNight
45%345%35%5%6%10%51%
1440
21st to endNight
6%5%25%7%5%7%9%9%11%35%
1666
August1st to 10thNight
5%5%25%6%5%6%6%8%10%40%
1625
11th to 20thNight
6%5%25%5%45%6%6%10%47%
1778
21st to endNight
5%4245%35%6%8%10%47%
1980
September1st to 10thNight
5%5%245%45%6%6%10%49%
1800
11th to 20thNight
43243245%6%7%60%
1818
21st to endNight
45%23434445%62%
1980
October1st to 10thNight
44134245%5%7%61%
2142
11th to 20thNight
1312313346%71%
2160
21st to endNight
45%2432435%6%62%
2399
November1st to 10thNight
1323313349%68%
2405
11th to 20thNight
32442435%7%66%
2470
21st to endNight
15%3442335%7%62%
2531
December1st to 10thNight
1325%3245%5%10%62%
2660
11th to 20thNight
1425%5%35%5%6%10%55%
3271
21st to endNight
16%36%5%35%5%5%7%53%
4873

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
19%8%16%25%25%7%
2539
11th to 20thDay
22%7%13%30%21%6%
2681
21st to endDay
26%8%13%27%21%5%
3146
February1st to 10thDay
26%5%14%26%19%9%
1710
11th to 20thDay
20%5%11%26%29%9%
1851
21st to endDay
25%47%23%27%13%
1570
March1st to 10thDay
27%5%9%25%25%8%
1900
11th to 20thDay
34%6%10%25%20%5%
2075
21st to endDay
33%7%10%25%20%5%
2329
April1st to 10thDay
33%6%11%21%19%9%
2160
11th to 20thDay
39%6%9%21%19%6%
2134
21st to endDay
41%7%10%22%17%3
2160
May1st to 10thDay
42%9%11%20%15%3
2240
11th to 20thDay
43%10%15%18%12%2
2445
21st to endDay
34%10%13%20%16%7%
2724
June1st to 10thDay
31%10%15%18%18%9%
2520
11th to 20thDay
28%8%10%17%22%16%
2520
21st to endDay
32%9%12%19%19%9%
2520
July1st to 10thDay
37%9%11%16%19%8%
2451
11th to 20thDay
36%8%14%22%14%6%
2445
21st to endDay
46%11%17%15%10%2
2502
August1st to 10thDay
44%10%15%13%13%5%
2296
11th to 20thDay
33%9%12%19%18%9%
2123
21st to endDay
35%7%13%20%20%5%
2376
September1st to 10thDay
33%6%10%17%23%11%
2160
11th to 20thDay
29%6%9%18%27%12%
2142
21st to endDay
23%5%8%23%31%9%
1980
October1st to 10thDay
25%7%11%22%25%10%
1814
11th to 20thDay
18%47%23%34%13%
1800
21st to endDay
24%48%26%27%10%
1936
November1st to 10thDay
17%410%22%32%15%
1673
11th to 20thDay
18%5%8%32%28%9%
1710
21st to endDay
23%49%24%27%13%
1646
December1st to 10thDay
20%6%16%26%24%8%
1520
11th to 20thDay
21%7%14%26%25%8%
1924
21st to endDay
23%7%13%23%24%10%
2794
January1st to 10thNight
23%6%13%27%26%5%
4417
11th to 20thNight
14%6%13%34%24%9%
4306
21st to endNight
23%7%13%29%23%5%
4521
February1st to 10thNight
23%413%30%22%8%
2470
11th to 20thNight
25%411%28%24%8%
2223
21st to endNight
21%48%26%29%12%
1884
March1st to 10thNight
22%5%10%25%31%7%
2280
11th to 20thNight
28%6%11%29%22%5%
2103
21st to endNight
27%6%11%26%25%4
2071
April1st to 10thNight
26%5%11%27%24%7%
1800
11th to 20thNight
32%5%12%26%19%5%
1777
21st to endNight
33%7%13%26%17%4
1800
May1st to 10thNight
34%7%14%27%14%4
1720
11th to 20thNight
36%10%19%20%13%2
1452
21st to endNight
31%8%15%22%17%7%
1552
June1st to 10thNight
23%9%21%24%13%11%
1440
11th to 20thNight
17%10%14%21%21%17%
1440
21st to endNight
26%9%12%22%21%11%
1440
July1st to 10thNight
34%10%15%18%15%7%
1400
11th to 20thNight
27%8%18%29%15%5%
1392
21st to endNight
36%14%22%20%8%1
1573
August1st to 10thNight
35%12%19%18%12%5%
1616
11th to 20thNight
31%8%15%24%17%5%
1778
21st to endNight
28%8%17%26%17%4
1980
September1st to 10thNight
29%7%13%22%21%7%
1800
11th to 20thNight
23%5%13%21%25%13%
1818
21st to endNight
24%5%9%26%29%7%
1980
October1st to 10thNight
22%7%13%22%25%10%
2142
11th to 20thNight
14%411%23%34%13%
2160
21st to endNight
21%5%8%29%27%10%
2399
November1st to 10thNight
15%412%25%30%14%
2405
11th to 20thNight
17%49%30%29%10%
2470
21st to endNight
22%410%23%29%12%
2531
December1st to 10thNight
19%6%16%26%25%9%
2660
11th to 20thNight
22%6%14%24%28%6%
3272
21st to endNight
24%8%12%22%24%10%
4873

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
14%23%30%23%9%
270
11th to 20thDay
15%30%31%19%41
270
21st to endDay
6%28%39%19%6%1
297
February1st to 10thDay
10%41%34%11%21
270
11th to 20thDay
11%37%38%9%5%
270
21st to endDay
20%36%31%11%2
225
March1st to 10thDay
17%25%34%16%8%
270
11th to 20thDay
16%27%34%16%6%1
445
21st to endDay
19%32%33%13%3
471
April1st to 10thDay
15%33%34%14%21
420
11th to 20thDay
25%30%29%12%4
412
21st to endDay
20%32%30%14%41
420
May1st to 10thDay
14%25%35%19%6%2
503
11th to 20thDay
13%16%33%26%11%2
625
21st to endDay
10%19%29%27%13%2
679
June1st to 10thDay
7%13%30%27%20%3
630
11th to 20thDay
10%13%33%27%14%3
630
21st to endDay
5%11%31%30%18%5%
630
July1st to 10thDay
7%423%36%24%6%
621
11th to 20thDay
8%323%33%25%8%
618
21st to endDay
11%418%34%27%7%
591
August1st to 10thDay
12%7%27%35%16%4
447
11th to 20thDay
8%6%30%33%17%5%
437
21st to endDay
9%7%32%32%17%4
495
September1st to 10thDay
6%12%29%35%13%5%
450
11th to 20thDay
6%13%36%29%13%2
432
21st to endDay
8%13%26%28%19%6%
270
October1st to 10thDay
10%16%26%22%19%7%
270
11th to 20thDay
7%24%29%26%10%3
270
21st to endDay
12%22%32%22%10%2
297
November1st to 10thDay
11%24%34%18%11%3
270
11th to 20thDay
10%24%37%19%9%1
270
21st to endDay
10%23%39%19%7%2
270
December1st to 10thDay
13%30%33%17%7%1
270
11th to 20thDay
10%30%38%16%6%
270
21st to endDay
13%32%34%16%41
297
January1st to 10thNight
6%24%35%25%9%2
950
11th to 20thNight
5%30%35%21%7%1
878
21st to endNight
217%45%28%6%1
836
February1st to 10thNight
426%47%19%4
760
11th to 20thNight
424%47%21%4
744
21st to endNight
5%28%45%21%2
628
March1st to 10thNight
424%43%24%5%1
760
11th to 20thNight
6%16%39%31%8%
760
21st to endNight
6%19%47%23%5%
671
April1st to 10thNight
9%20%41%24%5%
540
11th to 20thNight
9%22%37%26%6%1
533
21st to endNight
11%18%37%25%8%1
540
May1st to 10thNight
10%10%37%34%9%1
540
11th to 20thNight
10%9%28%39%13%1
531
21st to endNight
7%12%34%31%15%1
584
June1st to 10thNight
46%25%42%19%3
540
11th to 20thNight
49%29%42%15%2
540
21st to endNight
4321%46%23%3
540
July1st to 10thNight
5%217%40%33%3
525
11th to 20thNight
5%115%39%36%4
522
21st to endNight
7%28%39%40%4
591
August1st to 10thNight
8%312%40%33%5%
537
11th to 20thNight
7%216%43%28%4
534
21st to endNight
7%216%38%33%5%
594
September1st to 10thNight
5%320%40%26%5%
540
11th to 20thNight
5%424%42%22%4
540
21st to endNight
5%8%29%37%19%3
540
October1st to 10thNight
6%11%34%33%14%3
702
11th to 20thNight
313%35%32%13%3
720
21st to endNight
7%13%36%29%13%2
815
November1st to 10thNight
415%38%30%11%2
925
11th to 20thNight
5%20%41%24%8%2
950
21st to endNight
5%18%40%29%8%1
950
December1st to 10thNight
5%27%35%26%6%1
950
11th to 20thNight
425%44%20%7%1
950
21st to endNight
7%28%38%21%6%
1045
Page generated at 2024-03-19 21:31:08. Version ac07

Copyright © 2024 Attilla Danko.


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