Breckenridge
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Breckenridge 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
39%
24537
23%
74442
13%
24483
50%
24483
32%
41630

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
27%
950
22%
2647
9%
946
39%
946
27%
1546
January11th to 20thNight
24%
801
26%
2429
11%
801
40%
801
26%
1401
January21st to endNight
21%
792
23%
2574
9%
792
38%
792
28%
1447
February1st to 10thNight
18%
720
20%
2340
6%
720
35%
720
22%
1392
February11th to 20thNight
21%
704
20%
2168
5%
700
38%
700
25%
1251
February21st to endNight
18%
592
24%
1776
6%
592
37%
592
25%
1044
March1st to 10thNight
27%
720
24%
2116
8%
720
41%
720
31%
1195
March11th to 20thNight
35%
720
23%
1980
13%
720
42%
720
35%
1133
March21st to endNight
22%
702
20%
2088
6%
702
35%
702
25%
1261
April1st to 10thNight
27%
540
22%
1800
7%
540
45%
540
26%
973
April11th to 20thNight
28%
533
19%
1777
12%
533
39%
533
24%
1043
April21st to endNight
35%
540
21%
1800
12%
540
48%
540
27%
1024
May1st to 10thNight
34%
540
20%
1703
11%
540
46%
540
30%
996
May11th to 20thNight
46%
531
15%
1418
11%
531
50%
531
31%
903
May21st to endNight
47%
584
21%
1552
11%
582
56%
582
36%
897
June1st to 10thNight
56%
540
25%
1440
16%
540
63%
540
46%
763
June11th to 20thNight
54%
540
27%
1440
18%
540
60%
540
47%
766
June21st to endNight
65%
540
26%
1440
21%
540
69%
540
52%
745
July1st to 10thNight
70%
525
18%
1400
16%
525
72%
525
35%
871
July11th to 20thNight
76%
522
23%
1392
20%
522
78%
522
43%
782
July21st to endNight
73%
591
15%
1616
13%
558
75%
558
29%
1009
August1st to 10thNight
65%
537
14%
1602
13%
534
66%
534
30%
961
August11th to 20thNight
69%
534
24%
1731
24%
534
73%
534
37%
932
August21st to endNight
69%
594
25%
1980
26%
594
73%
594
33%
1118
September1st to 10thNight
69%
540
30%
1800
28%
540
76%
540
39%
934
September11th to 20thNight
68%
540
33%
1800
29%
540
75%
540
41%
914
September21st to endNight
56%
592
29%
2009
21%
592
68%
592
41%
998
October1st to 10thNight
46%
720
26%
2160
14%
720
56%
720
38%
1160
October11th to 20thNight
41%
720
32%
2160
15%
720
54%
720
44%
1025
October21st to endNight
38%
792
31%
2376
13%
792
52%
792
36%
1287
November1st to 10thNight
35%
909
30%
2389
11%
909
48%
909
43%
1279
November11th to 20thNight
28%
950
31%
2470
11%
950
42%
950
38%
1352
November21st to endNight
33%
950
26%
2619
11%
950
44%
950
37%
1445
December1st to 10thNight
23%
950
22%
2660
6%
950
36%
950
28%
1535
December11th to 20thNight
22%
948
22%
3110
8%
948
34%
948
23%
1797
December21st to endNight
19%
1034
13%
4680
5%
1026
31%
1026
15%
2451

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
47%48%7%45%5%5%7%43%
74733
Night
1426%6%45%5%6%8%52%
74986
TransparencyDay
38%7%12%20%18%6%
74444
Night
26%8%16%25%19%6%
74797
SeeingDay
15%24%29%20%10%2
14362
Night
6%19%31%29%14%2
24550

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
249%8%5%7%46%8%48%
1518
11th to 20thDay
3310%8%45%5%5%8%49%
1557
21st to endDay
4413%11%45%35%8%43%
1782
February1st to 10thDay
35%13%9%47%5%6%7%41%
1620
11th to 20thDay
35%10%10%5%5%5%6%6%46%
1680
21st to endDay
35%13%11%6%6%447%42%
1480
March1st to 10thDay
19%5%9%8%45%447%44%
1840
11th to 20thDay
18%5%11%9%35%45%6%43%
1980
21st to endDay
18%7%12%9%5%6%45%7%35%
2268
April1st to 10thDay
17%5%9%8%46%6%5%6%44%
2160
11th to 20thDay
211%8%12%9%5%5%35%6%34%
2131
21st to endDay
313%6%11%8%45%6%5%6%33%
2160
May1st to 10thDay
414%410%9%45%5%5%7%33%
2254
11th to 20thDay
6%13%5%8%6%46%6%5%8%34%
2478
21st to endDay
6%11%48%7%46%5%5%8%35%
2724
June1st to 10thDay
5%6%36%5%35%6%7%10%44%
2520
11th to 20thDay
7%6%25%5%35%5%5%6%51%
2520
21st to endDay
5%5%26%5%46%5%6%7%48%
2520
July1st to 10thDay
9%5%46%7%36%6%6%7%40%
2520
11th to 20thDay
8%6%27%8%5%6%7%6%9%37%
2520
21st to endDay
11%8%48%8%5%7%6%7%8%29%
2603
August1st to 10thDay
13%8%49%7%45%6%6%7%31%
2328
11th to 20thDay
9%6%36%7%45%46%8%41%
2170
21st to endDay
8%7%38%7%46%6%6%7%39%
2376
September1st to 10thDay
8%6%36%5%35%445%51%
2160
11th to 20thDay
8%6%26%5%35%45%7%50%
2160
21st to endDay
5%7%36%5%33345%56%
1947
October1st to 10thDay
5%7%36%6%45%446%50%
1800
11th to 20thDay
27%3443445%6%60%
1800
21st to endDay
27%37%6%35%346%54%
1976
November1st to 10thDay
425%5%2445%7%62%
1673
11th to 20thDay
437%5%3335%8%59%
1710
21st to endDay
347%8%34437%56%
1558
December1st to 10thDay
339%10%6%6%5%5%9%44%
1520
11th to 20thDay
348%8%45%5%6%11%46%
1926
21st to endDay
4310%11%5%7%5%5%8%42%
2794
January1st to 10thNight
226%9%46%5%8%9%49%
2647
11th to 20thNight
236%7%37%5%6%11%50%
2429
21st to endNight
227%8%6%8%6%6%8%46%
2574
February1st to 10thNight
129%9%5%6%7%7%8%46%
2340
11th to 20thNight
327%9%5%6%7%7%9%45%
2167
21st to endNight
239%9%6%6%5%6%9%44%
1776
March1st to 10thNight
436%7%46%47%8%52%
2116
11th to 20thNight
15%47%7%345%5%7%53%
1980
21st to endNight
15%5%9%8%5%5%45%7%47%
2088
April1st to 10thNight
425%6%46%45%9%54%
1800
11th to 20thNight
18%39%8%46%6%5%7%44%
1777
21st to endNight
38%37%5%3445%9%48%
1800
May1st to 10thNight
38%36%6%35%46%9%47%
1703
11th to 20thNight
39%36%6%445%7%8%44%
1417
21st to endNight
37%45%5%35%46%9%52%
1552
June1st to 10thNight
24133345%6%10%59%
1440
11th to 20thNight
332332445%7%64%
1440
21st to endNight
231442437%9%61%
1440
July1st to 10thNight
5%3245%36%6%8%10%47%
1440
11th to 20thNight
2313436%7%7%10%54%
1440
21st to endNight
5%5%246%46%6%9%12%42%
1711
August1st to 10thNight
6%5%36%5%25%6%7%10%45%
1611
11th to 20thNight
5%5%23435%5%7%8%54%
1731
21st to endNight
5%435%435%6%6%8%51%
1980
September1st to 10thNight
3425%4345%6%8%56%
1800
11th to 20thNight
34244345%5%7%61%
1800
21st to endNight
24245%34447%60%
2009
October1st to 10thNight
35%24435%5%6%7%57%
2160
11th to 20thNight
142343335%5%67%
2160
21st to endNight
16%37%6%33447%57%
2376
November1st to 10thNight
32442446%7%65%
2389
11th to 20thNight
226%5%3436%8%60%
2470
21st to endNight
337%6%345%6%9%54%
2619
December1st to 10thNight
228%8%45%46%9%53%
2660
11th to 20thNight
237%8%47%5%7%11%47%
3271
21st to endNight
338%11%5%6%5%6%9%45%
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
31%8%18%22%17%4
1519
11th to 20thDay
33%9%17%20%17%4
1557
21st to endDay
37%6%17%23%12%5%
1782
February1st to 10thDay
39%8%17%18%12%5%
1620
11th to 20thDay
36%6%13%22%17%6%
1689
21st to endDay
40%5%14%19%17%6%
1480
March1st to 10thDay
38%6%11%24%19%2
1840
11th to 20thDay
40%5%16%22%14%4
1980
21st to endDay
45%6%12%23%11%3
2268
April1st to 10thDay
39%7%13%19%15%7%
2160
11th to 20thDay
51%412%16%14%3
2134
21st to endDay
48%6%9%24%10%1
2160
May1st to 10thDay
47%7%10%21%13%1
2254
11th to 20thDay
48%7%13%22%9%1
2482
21st to endDay
46%7%11%20%13%4
2724
June1st to 10thDay
33%7%13%23%18%6%
2520
11th to 20thDay
33%5%9%18%22%13%
2520
21st to endDay
32%6%8%19%23%11%
2520
July1st to 10thDay
39%7%10%16%18%9%
2451
11th to 20thDay
41%9%13%17%12%7%
2445
21st to endDay
49%11%15%14%10%2
2458
August1st to 10thDay
50%9%11%12%15%4
2313
11th to 20thDay
41%7%11%17%19%7%
2170
21st to endDay
42%7%11%19%16%5%
2376
September1st to 10thDay
35%48%14%27%11%
2160
11th to 20thDay
34%5%10%18%24%8%
2160
21st to endDay
30%47%26%27%6%
1947
October1st to 10thDay
34%5%10%20%24%7%
1800
11th to 20thDay
25%48%29%27%8%
1800
21st to endDay
31%5%10%26%20%6%
1976
November1st to 10thDay
21%6%14%22%32%5%
1673
11th to 20thDay
21%6%16%29%20%7%
1710
21st to endDay
28%5%12%27%17%11%
1558
December1st to 10thDay
34%10%15%22%15%4
1520
11th to 20thDay
30%8%13%29%18%2
1924
21st to endDay
35%6%14%16%22%7%
2794
January1st to 10thNight
26%10%20%25%16%4
2647
11th to 20thNight
25%12%19%23%16%5%
2429
21st to endNight
28%8%20%25%14%5%
2574
February1st to 10thNight
29%11%18%22%16%4
2340
11th to 20thNight
29%7%17%23%19%4
2168
21st to endNight
31%6%17%21%20%6%
1776
March1st to 10thNight
25%8%14%28%22%3
2116
11th to 20thNight
26%6%18%30%15%5%
1980
21st to endNight
33%7%18%28%12%3
2088
April1st to 10thNight
26%9%16%24%20%5%
1800
11th to 20thNight
35%6%16%25%16%2
1777
21st to endNight
31%7%17%29%15%1
1800
May1st to 10thNight
32%7%16%30%14%1
1703
11th to 20thNight
34%8%19%26%12%
1418
21st to endNight
28%7%15%26%21%4
1552
June1st to 10thNight
19%8%19%30%19%6%
1440
11th to 20thNight
20%6%12%22%27%13%
1440
21st to endNight
18%6%14%24%26%12%
1440
July1st to 10thNight
28%12%14%19%18%9%
1400
11th to 20thNight
23%9%19%25%17%7%
1392
21st to endNight
30%14%23%21%9%2
1616
August1st to 10thNight
32%10%21%19%14%5%
1602
11th to 20thNight
25%8%18%22%21%6%
1731
21st to endNight
29%9%14%25%19%4
1980
September1st to 10thNight
24%7%13%21%26%9%
1800
11th to 20thNight
22%8%13%24%24%10%
1800
21st to endNight
22%5%11%33%24%5%
2009
October1st to 10thNight
22%8%14%26%23%8%
2160
11th to 20thNight
16%5%12%32%27%8%
2160
21st to endNight
26%5%13%28%22%6%
2376
November1st to 10thNight
18%7%15%26%28%6%
2389
11th to 20thNight
20%6%16%31%22%6%
2470
21st to endNight
25%6%13%28%21%8%
2619
December1st to 10thNight
25%9%20%23%17%6%
2660
11th to 20thNight
28%9%15%22%22%4
3272
21st to endNight
30%8%14%18%20%9%
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
18%29%21%21%8%2
270
11th to 20thDay
11%33%32%20%31
240
21st to endDay
11%42%33%12%2
264
February1st to 10thDay
23%42%26%8%11
240
11th to 20thDay
25%35%26%12%2
240
21st to endDay
27%33%26%13%1
198
March1st to 10thDay
23%33%26%15%4
280
11th to 20thDay
16%33%31%17%3
420
21st to endDay
17%41%30%11%1
462
April1st to 10thDay
18%40%28%11%21
420
11th to 20thDay
26%37%23%11%21
412
21st to endDay
18%37%32%9%31
420
May1st to 10thDay
19%28%33%15%5%1
463
11th to 20thDay
15%18%32%24%9%2
625
21st to endDay
16%20%28%23%12%2
679
June1st to 10thDay
9%18%26%25%18%3
630
11th to 20thDay
11%19%30%25%12%3
630
21st to endDay
6%17%31%25%18%3
630
July1st to 10thDay
10%7%24%31%24%5%
621
11th to 20thDay
9%7%24%29%23%7%
618
21st to endDay
14%9%26%26%20%6%
545
August1st to 10thDay
16%13%28%27%13%4
447
11th to 20thDay
11%9%31%28%16%5%
437
21st to endDay
12%13%28%30%13%4
495
September1st to 10thDay
12%15%30%25%12%6%
450
11th to 20thDay
11%14%36%25%11%2
450
21st to endDay
11%22%25%23%14%6%
292
October1st to 10thDay
13%21%26%21%16%4
270
11th to 20thDay
14%30%25%19%9%2
270
21st to endDay
18%29%26%17%8%1
297
November1st to 10thDay
16%36%27%15%6%1
270
11th to 20thDay
19%31%29%14%6%2
270
21st to endDay
8%30%40%17%4
270
December1st to 10thDay
17%34%27%14%7%1
270
11th to 20thDay
14%34%34%13%41
270
21st to endDay
21%33%28%13%5%
297
January1st to 10thNight
9%29%30%22%9%1
950
11th to 20thNight
8%28%34%21%7%2
801
21st to endNight
427%43%20%5%1
792
February1st to 10thNight
6%31%41%16%5%1
720
11th to 20thNight
5%32%38%21%4
704
21st to endNight
5%32%39%20%4
592
March1st to 10thNight
5%25%37%27%5%
720
11th to 20thNight
5%20%37%29%9%
720
21st to endNight
5%25%43%22%5%
702
April1st to 10thNight
6%23%41%26%4
540
11th to 20thNight
8%24%34%25%8%
533
21st to endNight
7%21%34%29%9%1
540
May1st to 10thNight
7%13%39%30%10%1
540
11th to 20thNight
8%10%28%38%15%1
531
21st to endNight
8%13%26%36%16%2
584
June1st to 10thNight
47%27%39%22%2
540
11th to 20thNight
410%27%45%13%1
540
21st to endNight
35%20%40%29%1
540
July1st to 10thNight
5%213%38%38%3
525
11th to 20thNight
3110%41%40%5%
522
21st to endNight
6%29%35%44%4
591
August1st to 10thNight
9%213%38%35%3
537
11th to 20thNight
5%215%42%32%4
534
21st to endNight
6%214%40%34%4
594
September1st to 10thNight
4315%47%26%5%
540
11th to 20thNight
6%319%46%24%3
540
21st to endNight
49%25%38%21%4
592
October1st to 10thNight
314%32%33%14%4
720
11th to 20thNight
6%20%30%29%14%2
720
21st to endNight
6%18%34%30%10%2
792
November1st to 10thNight
5%22%35%29%9%1
909
11th to 20thNight
7%28%34%24%5%2
950
21st to endNight
423%37%29%7%1
950
December1st to 10thNight
7%30%37%20%5%
950
11th to 20thNight
7%30%35%21%6%1
950
21st to endNight
11%28%35%21%5%1
1045
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