Greeley
Clear Sky Chart
History

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

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
57%
24597
26%
74412
19%
24552
63%
24552
38%
41770

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
56%
947
30%
2647
20%
946
64%
946
44%
1464
January11th to 20thNight
50%
905
29%
2533
20%
905
58%
905
40%
1441
January21st to endNight
51%
814
29%
2596
21%
814
61%
814
35%
1471
February1st to 10thNight
45%
720
23%
2340
16%
720
55%
720
33%
1327
February11th to 20thNight
46%
701
24%
2115
16%
700
54%
700
33%
1260
February21st to endNight
44%
592
31%
1776
17%
592
56%
592
36%
1019
March1st to 10thNight
51%
720
25%
2160
15%
720
59%
720
39%
1201
March11th to 20thNight
53%
720
26%
2034
17%
720
59%
720
39%
1189
March21st to endNight
44%
640
22%
2026
13%
640
54%
640
31%
1219
April1st to 10thNight
39%
540
23%
1800
16%
540
50%
540
30%
1019
April11th to 20thNight
40%
533
20%
1777
14%
533
51%
533
26%
1060
April21st to endNight
46%
540
20%
1800
19%
540
52%
540
26%
1093
May1st to 10thNight
48%
540
17%
1644
15%
540
52%
540
26%
1066
May11th to 20thNight
51%
531
16%
1421
14%
531
52%
531
29%
943
May21st to endNight
56%
582
16%
1552
13%
582
59%
582
32%
983
June1st to 10thNight
67%
540
19%
1440
15%
540
68%
540
45%
811
June11th to 20thNight
62%
540
23%
1440
16%
540
67%
540
44%
817
June21st to endNight
69%
540
24%
1440
20%
540
70%
540
46%
804
July1st to 10thNight
70%
525
18%
1400
16%
525
70%
525
39%
841
July11th to 20thNight
75%
522
27%
1392
24%
522
76%
522
47%
766
July21st to endNight
76%
591
24%
1488
22%
558
76%
558
38%
887
August1st to 10thNight
69%
537
16%
1585
15%
534
70%
534
31%
961
August11th to 20thNight
75%
534
26%
1778
29%
534
77%
534
42%
890
August21st to endNight
73%
594
27%
1980
30%
594
75%
594
40%
1025
September1st to 10thNight
66%
540
28%
1800
28%
540
72%
540
39%
927
September11th to 20thNight
70%
540
34%
1834
35%
540
76%
540
45%
885
September21st to endNight
65%
540
33%
1980
31%
540
72%
540
42%
910
October1st to 10thNight
60%
679
28%
2119
21%
679
65%
679
39%
1152
October11th to 20thNight
60%
720
33%
2160
20%
720
68%
720
49%
1078
October21st to endNight
58%
874
31%
2458
19%
874
64%
874
43%
1360
November1st to 10thNight
62%
925
30%
2405
18%
925
67%
925
51%
1321
November11th to 20thNight
56%
950
34%
2470
20%
950
63%
950
48%
1379
November21st to endNight
57%
950
29%
2569
19%
950
63%
950
44%
1455
December1st to 10thNight
55%
950
25%
2660
16%
950
61%
950
41%
1514
December11th to 20thNight
54%
948
29%
3085
19%
948
60%
948
38%
1629
December21st to endNight
50%
1033
17%
4708
15%
1026
59%
1026
23%
2603

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
6%5%244345%6%8%52%
74769
Night
6%6%25%43445%7%54%
74946
TransparencyDay
28%6%12%24%22%8%
74473
Night
29%5%12%25%22%7%
74764
SeeingDay
8%6%20%34%24%8%
14475
Night
8%424%48%16%1
24619

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
37%2442345%9%57%
1518
11th to 20thDay
38%35%43445%7%54%
1440
21st to endDay
28%46%5%35%5%5%7%51%
1778
February1st to 10thDay
38%5%6%6%335%6%7%49%
1620
11th to 20thDay
26%45%435%5%5%9%52%
1731
21st to endDay
38%36%5%345%5%7%51%
1480
March1st to 10thDay
46%345%35%45%7%54%
1800
11th to 20thDay
6%5%35%5%36%46%8%50%
1924
21st to endDay
7%6%25%5%35%5%6%9%46%
2329
April1st to 10thDay
8%5%244345%6%8%51%
2160
11th to 20thDay
11%8%25%5%3446%8%45%
2131
21st to endDay
10%6%35%5%35%5%6%9%43%
2160
May1st to 10thDay
13%6%25%5%35%5%6%8%41%
2313
11th to 20thDay
14%6%25%5%345%7%10%39%
2471
21st to endDay
7%5%245%45%6%7%10%44%
2724
June1st to 10thDay
5%413435%6%7%11%51%
2520
11th to 20thDay
6%324335%6%7%9%52%
2520
21st to endDay
4313425%7%7%9%54%
2520
July1st to 10thDay
6%324435%6%6%11%50%
2520
11th to 20thDay
3313435%6%7%10%56%
2520
21st to endDay
4325%5%46%6%8%10%47%
2742
August1st to 10thDay
44245%46%7%9%11%43%
2343
11th to 20thDay
3313435%5%7%8%57%
2123
21st to endDay
4323435%5%8%9%56%
2376
September1st to 10thDay
5%32332445%8%61%
2160
11th to 20thDay
6%21442445%7%60%
2124
21st to endDay
7%322323436%65%
1980
October1st to 10thDay
8%5%2332335%8%58%
1836
11th to 20thDay
5%41322245%6%66%
1800
21st to endDay
6%6%24333346%61%
1877
November1st to 10thDay
342443446%8%59%
1673
11th to 20thDay
47%23324348%59%
1710
21st to endDay
36%3433345%8%57%
1606
December1st to 10thDay
27%25%5%3346%8%55%
1520
11th to 20thDay
46%35%4245%5%8%54%
1926
21st to endDay
5%9%37%6%34446%49%
2794
January1st to 10thNight
36%35%423347%59%
2647
11th to 20thNight
26%36%5%3445%7%56%
2533
21st to endNight
48%36%6%335%5%6%52%
2596
February1st to 10thNight
39%47%5%34447%52%
2340
11th to 20thNight
48%46%6%35%45%6%50%
2115
21st to endNight
410%37%42335%5%55%
1776
March1st to 10thNight
47%36%43436%7%55%
2160
11th to 20thNight
8%5%24434447%55%
2034
21st to endNight
7%8%45%5%3446%7%47%
2026
April1st to 10thNight
8%7%35%5%24446%52%
1800
11th to 20thNight
12%7%35%5%3435%6%46%
1777
21st to endNight
14%8%25%5%345%5%7%44%
1800
May1st to 10thNight
14%6%345%35%46%8%42%
1644
11th to 20thNight
17%5%25%42435%8%45%
1420
21st to endNight
9%5%24346%6%6%9%47%
1552
June1st to 10thNight
6%3243335%6%11%54%
1440
11th to 20thNight
7%213435%45%8%59%
1440
21st to endNight
5%31443347%9%57%
1440
July1st to 10thNight
8%3245%345%7%10%50%
1440
11th to 20thNight
3313435%6%7%9%57%
1440
21st to endNight
4425%5%45%6%7%9%49%
1576
August1st to 10thNight
6%4246%45%7%7%10%45%
1593
11th to 20thNight
43244245%6%10%56%
1778
21st to endNight
43235%26%6%5%9%55%
1980
September1st to 10thNight
7%32443346%8%57%
1800
11th to 20thNight
6%4133245%46%61%
1834
21st to endNight
7%21432335%6%63%
1980
October1st to 10thNight
10%5%23323346%58%
2119
11th to 20thNight
6%323323446%64%
2160
21st to endNight
7%7%25%312337%59%
2458
November1st to 10thNight
442442345%7%62%
2405
11th to 20thNight
5%425%32435%6%60%
2470
21st to endNight
47%345%23347%58%
2569
December1st to 10thNight
36%345%345%5%7%56%
2660
11th to 20thNight
36%244335%6%9%55%
3271
21st to endNight
6%10%36%5%3445%7%48%
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
24%5%12%32%22%5%
1519
11th to 20thDay
29%411%29%22%5%
1440
21st to endDay
31%412%29%18%6%
1778
February1st to 10thDay
34%5%13%26%16%5%
1620
11th to 20thDay
28%6%9%29%22%5%
1741
21st to endDay
31%411%26%21%7%
1480
March1st to 10thDay
29%5%12%25%24%6%
1800
11th to 20thDay
30%6%13%23%21%6%
1924
21st to endDay
33%6%17%25%15%4
2329
April1st to 10thDay
29%7%14%23%18%8%
2160
11th to 20thDay
37%5%13%22%17%7%
2134
21st to endDay
35%7%12%25%20%2
2160
May1st to 10thDay
40%7%13%24%13%3
2313
11th to 20thDay
39%10%13%24%13%2
2475
21st to endDay
32%9%19%21%14%5%
2724
June1st to 10thDay
24%9%18%23%17%7%
2520
11th to 20thDay
27%7%12%18%23%14%
2520
21st to endDay
22%7%12%23%24%12%
2520
July1st to 10thDay
25%8%13%21%21%11%
2451
11th to 20thDay
21%8%12%22%24%13%
2445
21st to endDay
28%10%14%24%18%7%
2590
August1st to 10thDay
29%10%17%22%14%8%
2327
11th to 20thDay
21%6%12%23%24%14%
2123
21st to endDay
22%7%11%21%27%13%
2376
September1st to 10thDay
21%49%21%25%20%
2160
11th to 20thDay
22%49%20%28%17%
2124
21st to endDay
21%5%7%21%35%11%
1980
October1st to 10thDay
26%5%9%22%28%10%
1836
11th to 20thDay
19%5%10%25%29%13%
1800
21st to endDay
26%49%26%23%13%
1877
November1st to 10thDay
22%5%12%25%25%11%
1673
11th to 20thDay
24%48%27%30%6%
1710
21st to endDay
26%411%23%28%9%
1606
December1st to 10thDay
26%6%13%30%20%6%
1520
11th to 20thDay
27%5%11%24%29%3
1924
21st to endDay
36%5%10%23%22%5%
2794
January1st to 10thNight
27%412%30%22%5%
2647
11th to 20thNight
28%5%10%26%27%5%
2533
21st to endNight
32%5%10%30%19%5%
2596
February1st to 10thNight
32%5%13%26%19%4
2340
11th to 20thNight
34%5%10%27%19%4
2115
21st to endNight
33%38%25%23%8%
1776
March1st to 10thNight
28%5%11%23%26%7%
2160
11th to 20thNight
29%5%10%23%28%4
2034
21st to endNight
35%6%14%25%16%4
2026
April1st to 10thNight
33%6%11%24%19%8%
1800
11th to 20thNight
37%6%13%22%17%5%
1777
21st to endNight
39%5%11%24%18%3
1800
May1st to 10thNight
39%9%15%21%15%2
1644
11th to 20thNight
38%8%18%21%13%2
1421
21st to endNight
33%9%20%21%10%7%
1552
June1st to 10thNight
23%7%23%28%13%6%
1440
11th to 20thNight
24%7%14%21%21%13%
1440
21st to endNight
23%7%12%27%25%6%
1440
July1st to 10thNight
29%7%14%24%20%5%
1400
11th to 20thNight
21%8%13%27%20%11%
1392
21st to endNight
27%10%16%26%16%5%
1488
August1st to 10thNight
31%10%19%22%12%5%
1585
11th to 20thNight
23%6%13%26%22%11%
1778
21st to endNight
25%6%12%26%22%10%
1980
September1st to 10thNight
25%6%11%19%21%17%
1800
11th to 20thNight
21%5%12%24%23%15%
1834
21st to endNight
22%49%23%31%11%
1980
October1st to 10thNight
28%5%12%18%26%11%
2119
11th to 20thNight
20%5%12%24%26%13%
2160
21st to endNight
27%410%24%25%11%
2458
November1st to 10thNight
22%5%11%25%27%11%
2405
11th to 20thNight
24%410%28%27%7%
2470
21st to endNight
27%49%24%29%7%
2569
December1st to 10thNight
27%6%13%27%19%7%
2660
11th to 20thNight
26%410%30%27%3
3272
21st to endNight
36%5%10%25%21%3
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
7%5%16%43%24%6%
270
11th to 20thDay
8%6%16%49%18%3
240
21st to endDay
5%5%28%49%10%3
264
February1st to 10thDay
7%7%30%46%9%2
240
11th to 20thDay
5%5%32%43%13%2
240
21st to endDay
7%7%27%48%10%2
198
March1st to 10thDay
6%10%20%42%18%4
240
11th to 20thDay
10%10%28%35%15%3
364
21st to endDay
11%12%32%31%13%1
462
April1st to 10thDay
13%12%27%30%15%3
420
11th to 20thDay
16%17%29%26%9%3
412
21st to endDay
14%15%28%24%14%5%
420
May1st to 10thDay
14%8%26%32%17%3
576
11th to 20thDay
18%6%16%30%23%7%
625
21st to endDay
9%8%22%27%25%8%
679
June1st to 10thDay
5%415%32%31%13%
630
11th to 20thDay
7%323%36%26%6%
630
21st to endDay
4418%35%30%9%
630
July1st to 10thDay
8%213%28%36%13%
621
11th to 20thDay
3113%33%35%14%
618
21st to endDay
5%212%26%42%13%
684
August1st to 10thDay
5%215%33%33%13%
462
11th to 20thDay
3316%32%32%14%
437
21st to endDay
4217%32%33%12%
495
September1st to 10thDay
6%316%34%28%13%
450
11th to 20thDay
4320%25%35%14%
414
21st to endDay
10%215%26%26%21%
270
October1st to 10thDay
12%414%26%25%18%
270
11th to 20thDay
36%19%38%23%11%
270
21st to endDay
10%5%23%33%22%7%
297
November1st to 10thDay
47%22%40%17%10%
270
11th to 20thDay
7%8%17%41%21%5%
270
21st to endDay
7%417%49%19%4
270
December1st to 10thDay
5%6%23%39%23%3
270
11th to 20thDay
6%5%20%55%14%
270
21st to endDay
6%7%26%44%14%3
297
January1st to 10thNight
6%426%49%13%2
950
11th to 20thNight
6%430%49%10%
905
21st to endNight
7%329%51%10%
814
February1st to 10thNight
7%434%47%8%1
720
11th to 20thNight
7%433%48%7%
704
21st to endNight
8%436%47%4
592
March1st to 10thNight
6%433%48%9%
720
11th to 20thNight
9%5%28%45%14%
720
21st to endNight
9%5%33%44%8%
640
April1st to 10thNight
11%7%36%42%4
540
11th to 20thNight
14%9%31%39%7%
533
21st to endNight
18%6%25%36%14%
540
May1st to 10thNight
16%5%25%41%14%
540
11th to 20thNight
19%419%39%17%1
531
21st to endNight
9%5%24%41%20%1
584
June1st to 10thNight
7%219%45%26%1
540
11th to 20thNight
7%223%53%15%
540
21st to endNight
6%217%52%22%1
540
July1st to 10thNight
7%212%44%34%1
525
11th to 20thNight
312%50%33%2
522
21st to endNight
5%17%46%38%2
591
August1st to 10thNight
6%112%46%34%1
537
11th to 20thNight
4112%54%28%1
534
21st to endNight
5%111%48%33%1
594
September1st to 10thNight
8%116%46%25%3
540
11th to 20thNight
8%214%47%26%2
540
21st to endNight
6%220%51%20%1
540
October1st to 10thNight
13%320%41%21%2
679
11th to 20thNight
7%326%44%19%1
720
21st to endNight
10%5%21%48%14%2
874
November1st to 10thNight
5%325%52%15%1
925
11th to 20thNight
6%5%27%53%9%1
950
21st to endNight
7%5%24%49%13%1
950
December1st to 10thNight
7%427%53%9%
950
11th to 20thNight
7%5%26%53%9%1
950
21st to endNight
8%5%27%51%8%1
1045
Page generated at 2024-01-08 09:14:16. Version ac07

Copyright 2024 Attilla Danko


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