Breckenridge
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Breckenridge clear sky chart from 2005-11-05 to 2017-09-16.

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%
15928
22%
46870
12%
15881
49%
15881
31%
27077

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
27%
891
21%
2497
8%
886
38%
886
26%
1472
January16th to endNight
25%
768
25%
2496
11%
768
42%
768
29%
1385
February1st to 15thNight
22%
702
16%
2278
6%
698
35%
698
22%
1380
February16th to endNight
21%
632
22%
1894
6%
632
38%
632
27%
1119
March1st to 15thNight
29%
720
22%
2070
8%
720
41%
720
32%
1180
March16th to endNight
26%
708
21%
2052
9%
708
38%
708
27%
1236
April1st to 15thNight
29%
539
19%
1798
9%
539
42%
539
25%
1004
April16th to endNight
31%
540
20%
1800
11%
540
43%
540
24%
1072
May1st to 15thNight
34%
540
17%
1612
8%
540
44%
540
26%
1023
May16th to endNight
46%
563
18%
1498
10%
561
53%
561
32%
908
June1st to 15thNight
51%
540
24%
1440
14%
540
60%
540
48%
745
June16th to endNight
65%
540
27%
1440
20%
540
70%
540
53%
737
July1st to 15thNight
70%
510
16%
1360
13%
510
72%
510
32%
866
July16th to endNight
74%
564
16%
1498
15%
531
75%
531
32%
915
August1st to 15thNight
65%
539
15%
1638
14%
536
67%
536
31%
962
August16th to endNight
68%
573
24%
1910
24%
573
72%
573
31%
1101
September1st to 15thNight
67%
540
27%
1800
24%
540
74%
540
34%
992
September16th to endNight
61%
528
30%
1789
23%
528
72%
528
41%
896
October1st to 15thNight
41%
660
26%
1980
15%
660
50%
660
37%
1058
October16th to endNight
41%
704
30%
2112
14%
704
54%
704
37%
1136
November1st to 15thNight
35%
867
28%
2267
11%
867
46%
867
39%
1272
November16th to endNight
33%
900
28%
2433
12%
900
44%
900
38%
1345
December1st to 15thNight
19%
900
16%
2520
4%
900
31%
900
25%
1547
December16th to endNight
24%
960
18%
2688
7%
960
33%
960
22%
1726

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
5%7%48%7%35%45%7%41%
47900
Night
1425%5%35%5%6%9%50%
47049
TransparencyDay
40%6%13%20%14%4
47581
Night
27%8%18%25%16%3
46870
SeeingDay
15%21%28%20%11%3
5817
Night
6%18%30%27%15%2
15930

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 15thDay
239%8%47%45%10%43%
1450
16th to endDay
45%9%8%2435%7%47%
1728
February1st to 15thDay
3413%9%35%46%7%41%
1585
16th to endDay
35%12%8%5%6%446%41%
1580
March1st to 15thDay
7%48%8%45%446%44%
1887
16th to endDay
19%6%10%7%45%447%38%
2172
April1st to 15thDay
29%5%9%7%35%45%5%39%
2150
16th to endDay
314%7%11%8%35%445%30%
2160
May1st to 15thDay
5%15%5%9%7%35%5%5%6%31%
2334
16th to endDay
7%12%49%6%35%45%8%32%
2616
June1st to 15thDay
7%6%35%4245%6%8%44%
2520
16th to endDay
4425%435%5%5%6%53%
2520
July1st to 15thDay
11%6%37%7%35%5%47%35%
2520
16th to endDay
11%6%48%8%5%6%5%5%7%30%
2564
August1st to 15thDay
14%8%49%6%45%446%30%
2313
16th to endDay
10%7%38%7%45%5%6%7%34%
2292
September1st to 15thDay
11%6%36%5%24345%46%
2160
16th to endDay
5%7%26%5%33335%51%
1859
October1st to 15thDay
5%7%46%5%33346%49%
1650
16th to endDay
37%26%5%2435%7%52%
1757
November1st to 15thDay
427%5%2336%7%56%
1583
16th to endDay
435%6%23437%57%
1524
December1st to 15thDay
339%7%6%6%5%6%10%41%
1440
16th to endDay
35%9%9%48%47%9%37%
1536
January1st to 15thNight
225%6%36%5%8%12%47%
2497
16th to endNight
235%6%47%5%5%9%50%
2496
February1st to 15thNight
227%8%46%7%6%9%44%
2267
16th to endNight
238%7%46%5%6%10%44%
1894
March1st to 15thNight
425%6%35%46%8%53%
2070
16th to endNight
15%47%6%34347%50%
2052
April1st to 15thNight
5%35%6%36%5%5%9%49%
1798
16th to endNight
210%26%5%35%447%46%
1800
May1st to 15thNight
48%35%6%3446%8%43%
1611
16th to endNight
36%35%5%35%46%9%48%
1497
June1st to 15thNight
221232345%9%62%
1440
16th to endNight
121332436%7%64%
1440
July1st to 15thNight
4325%5%37%6%8%9%44%
1440
16th to endNight
5%3245%35%5%7%10%45%
1601
August1st to 15thNight
5%5%25%415%5%6%9%46%
1647
16th to endNight
6%4245%345%6%9%48%
1910
September1st to 15thNight
44244345%5%7%53%
1800
16th to endNight
13135%23447%60%
1789
October1st to 15thNight
25%233345%6%8%55%
1980
16th to endNight
15%25%423345%60%
2112
November1st to 15thNight
214435%36%7%59%
2267
16th to endNight
225%5%2445%8%56%
2433
December1st to 15thNight
227%8%35%47%10%47%
2520
16th to endNight
228%9%46%5%6%12%42%
2688

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
33%10%22%19%10%3
1451
16th to endDay
33%7%19%22%13%3
1728
February1st to 15thDay
40%10%17%20%8%3
1585
16th to endDay
39%6%16%22%13%2
1580
March1st to 15thDay
36%6%15%24%14%1
1887
16th to endDay
42%6%13%24%10%3
2172
April1st to 15thDay
43%5%14%19%12%4
2150
16th to endDay
53%5%11%20%8%1
2160
May1st to 15thDay
51%6%11%20%9%
2334
16th to endDay
48%6%12%19%10%1
2620
June1st to 15thDay
36%411%18%21%7%
2520
16th to endDay
30%47%22%25%9%
2520
July1st to 15thDay
47%6%10%13%14%7%
2371
16th to endDay
51%8%14%13%9%3
2404
August1st to 15thDay
54%7%9%11%13%4
2298
16th to endDay
47%6%11%18%13%3
2292
September1st to 15thDay
41%49%16%21%8%
2160
16th to endDay
35%310%23%23%2
1859
October1st to 15thDay
35%310%24%21%3
1650
16th to endDay
30%5%10%28%20%3
1757
November1st to 15thDay
25%6%16%21%23%6%
1583
16th to endDay
25%6%16%30%16%6%
1524
December1st to 15thDay
34%10%18%24%10%1
1440
16th to endDay
41%11%14%18%10%3
1536
January1st to 15thNight
23%13%24%22%12%2
2497
16th to endNight
25%9%21%23%15%4
2496
February1st to 15thNight
30%11%20%24%11%1
2278
16th to endNight
29%7%19%24%16%3
1894
March1st to 15thNight
23%9%19%30%14%2
2070
16th to endNight
31%6%17%30%11%2
2052
April1st to 15thNight
28%8%17%27%15%2
1798
16th to endNight
34%7%17%27%12%1
1800
May1st to 15thNight
36%7%16%26%11%
1612
16th to endNight
31%6%17%28%13%2
1498
June1st to 15thNight
18%5%16%27%23%7%
1440
16th to endNight
18%412%26%27%11%
1440
July1st to 15thNight
31%11%15%17%16%7%
1360
16th to endNight
30%10%22%20%11%3
1498
August1st to 15thNight
32%7%20%18%14%5%
1638
16th to endNight
31%7%16%24%17%2
1910
September1st to 15thNight
28%7%14%21%20%7%
1800
16th to endNight
22%6%14%34%20%2
1789
October1st to 15thNight
23%5%16%28%20%4
1980
16th to endNight
24%6%13%31%22%3
2112
November1st to 15thNight
21%7%15%25%23%6%
2267
16th to endNight
23%5%16%29%20%4
2433
December1st to 15thNight
27%12%23%21%13%1
2520
16th to endNight
32%12%20%19%12%2
2688

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
17%21%25%20%13%2
90
16th to endDay
7%33%36%20%11
96
February1st to 15thDay
22%31%32%14%
90
16th to endDay
18%27%25%24%21
81
March1st to 15thDay
19%35%25%16%2
177
16th to endDay
15%43%29%10%1
288
April1st to 15thDay
17%41%27%8%21
269
16th to endDay
22%45%21%8%1
270
May1st to 15thDay
18%22%33%16%7%1
375
16th to endDay
17%20%28%19%10%3
517
June1st to 15thDay
10%20%26%23%17%3
495
16th to endDay
6%13%30%24%21%3
495
July1st to 15thDay
14%7%23%25%21%7%
475
16th to endDay
16%6%24%23%20%8%
423
August1st to 15thDay
21%13%24%27%10%2
315
16th to endDay
16%8%32%27%11%2
332
September1st to 15thDay
16%18%35%19%6%2
315
16th to endDay
12%14%35%20%10%6%
162
October1st to 15thDay
7%25%20%28%12%5%
90
16th to endDay
17%20%26%21%11%2
96
November1st to 15thDay
7%25%21%22%18%4
90
16th to endDay
17%31%36%13%1
90
December1st to 15thDay
18%38%31%8%2
90
16th to endDay
347%29%13%6%
96
January1st to 15thNight
8%28%30%19%9%2
891
16th to endNight
5%23%40%21%7%1
768
February1st to 15thNight
5%26%41%20%5%
704
16th to endNight
5%28%39%21%5%
632
March1st to 15thNight
5%21%37%25%8%
720
16th to endNight
5%23%39%24%6%
708
April1st to 15thNight
6%22%39%25%7%
539
16th to endNight
7%22%34%26%7%
540
May1st to 15thNight
9%13%35%29%11%
540
16th to endNight
7%12%27%32%18%1
563
June1st to 15thNight
38%30%35%19%1
540
16th to endNight
3421%40%28%1
540
July1st to 15thNight
5%112%35%42%3
510
16th to endNight
5%17%32%46%6%
564
August1st to 15thNight
9%12%35%37%3
539
16th to endNight
7%213%34%36%6%
573
September1st to 15thNight
5%117%42%26%5%
540
16th to endNight
37%22%34%27%5%
528
October1st to 15thNight
417%33%25%14%4
660
16th to endNight
5%16%31%28%14%3
704
November1st to 15thNight
6%21%32%27%10%1
867
16th to endNight
426%34%26%8%1
900
December1st to 15thNight
6%31%39%17%4
900
16th to endNight
7%28%33%22%7%
960
Page generated at 2017-09-17 10:05:47. Version ac04

Copyright 2017 A. Danko


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