Braidwood Dark Sky Site
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Braidwood Dark Sky Site clear sky chart from 2005-11-05 to 2018-02-14.

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
38%
16612
18%
48794
11%
16569
45%
16569
25%
32256

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
21%
975
14%
2716
5%
970
30%
970
19%
1952
January16th to endNight
22%
1040
13%
2857
5%
1040
28%
1040
17%
2139
February1st to 15thNight
24%
851
14%
2374
5%
851
31%
851
19%
1699
February16th to endNight
28%
631
18%
1893
8%
631
37%
631
18%
1321
March1st to 15thNight
27%
720
14%
2160
9%
720
32%
720
18%
1511
March16th to endNight
28%
618
15%
2010
9%
618
37%
618
20%
1382
April1st to 15thNight
30%
539
15%
1797
10%
539
39%
539
21%
1192
April16th to endNight
35%
540
18%
1749
12%
540
44%
540
23%
1174
May1st to 15thNight
37%
540
16%
1611
9%
540
43%
540
24%
1092
May16th to endNight
50%
563
19%
1498
11%
561
55%
561
34%
949
June1st to 15thNight
53%
540
17%
1440
11%
540
57%
540
37%
882
June16th to endNight
53%
540
18%
1440
11%
540
57%
540
35%
903
July1st to 15thNight
65%
510
17%
1360
12%
510
67%
510
37%
831
July16th to endNight
72%
564
24%
1417
19%
531
75%
531
46%
805
August1st to 15thNight
78%
539
22%
1603
22%
536
79%
536
43%
872
August16th to endNight
69%
573
22%
1910
22%
573
72%
573
35%
1066
September1st to 15thNight
64%
543
29%
1803
29%
543
69%
543
37%
962
September16th to endNight
61%
717
28%
1980
22%
717
64%
717
37%
1180
October1st to 15thNight
49%
720
27%
2070
20%
720
55%
720
34%
1234
October16th to endNight
30%
768
21%
2432
13%
768
40%
768
23%
1549
November1st to 15thNight
31%
760
23%
2471
16%
760
43%
760
24%
1522
November16th to endNight
28%
806
20%
2561
11%
806
39%
806
21%
1668
December1st to 15thNight
21%
975
12%
2730
4%
975
29%
975
18%
2004
December16th to endNight
17%
1040
11%
2912
3%
1040
23%
1040
11%
2367

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
14%7%35%5%3445%7%37%
49291
Night
14%7%35%5%24446%40%
48962
Cloud CoverDay
14%7%35%5%3445%7%37%
49300
Night
14%7%35%5%24446%40%
48967
TransparencyDay
45%412%22%12%1
48977
Night
44%411%22%14%2
48794
SeeingDay
16%7%25%25%18%6%
6418
Night
18%7%28%30%13%1
16615

By Month

Percentage Cloud Cover NE (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
16%13%5%7%6%4444426%
1552
16th to endDay
14%14%6%8%6%34446%26%
1719
February1st to 15thDay
16%12%6%6%5%25%446%28%
1788
16th to endDay
16%9%48%6%34346%31%
1580
March1st to 15thDay
17%12%46%425%446%29%
1790
16th to endDay
17%10%36%5%245%47%29%
2223
April1st to 15thDay
18%9%45%5%24346%34%
2151
16th to endDay
20%6%25%5%335%46%35%
2211
May1st to 15thDay
20%8%36%42445%8%30%
2337
16th to endDay
15%5%35%5%25%46%7%39%
2617
June1st to 15thDay
11%425%435%5%5%8%43%
2520
16th to endDay
10%425%5%36%6%6%9%37%
2520
July1st to 15thDay
8%4245%45%5%6%8%44%
2520
16th to endDay
6%3245%46%6%7%9%43%
2655
August1st to 15thDay
6%425%5%35%47%10%45%
2343
16th to endDay
8%5%245%35%5%5%7%44%
2292
September1st to 15thDay
12%314434345%50%
2145
16th to endDay
8%5%25%42445%7%48%
1980
October1st to 15thDay
16%7%24324446%42%
1887
16th to endDay
18%7%25%5%2445%5%38%
1791
November1st to 15thDay
16%6%2442345%6%41%
1717
16th to endDay
18%8%46%413336%38%
1729
December1st to 15thDay
17%12%47%6%45%33429%
1560
16th to endDay
20%15%6%6%5%34345%22%
1664
January1st to 15thNight
16%11%46%5%33345%34%
2716
16th to endNight
14%13%6%8%6%25%435%30%
2857
February1st to 15thNight
17%12%45%424346%34%
2372
16th to endNight
16%9%46%5%25%445%34%
1893
March1st to 15thNight
17%10%45%43435%5%34%
2147
16th to endNight
16%8%35%6%3445%6%33%
2010
April1st to 15thNight
15%7%46%5%145%46%38%
1797
16th to endNight
20%6%24434447%37%
1749
May1st to 15thNight
19%6%25%6%2345%9%34%
1611
16th to endNight
10%4245%25%47%9%44%
1496
June1st to 15thNight
10%5%2442435%6%49%
1440
16th to endNight
8%5%25%5%3446%9%44%
1440
July1st to 15thNight
7%314425%5%6%8%50%
1440
16th to endNight
4215%42446%9%54%
1513
August1st to 15thNight
43133345%6%9%53%
1612
16th to endNight
9%32332446%7%51%
1910
September1st to 15thNight
11%313323437%55%
1803
16th to endNight
8%4135%35%5%6%7%48%
1980
October1st to 15thNight
12%424423346%51%
2070
16th to endNight
18%7%25%413335%43%
2432
November1st to 15thNight
15%6%25%423435%45%
2471
16th to endNight
17%7%35%5%34346%39%
2561
December1st to 15thNight
18%10%48%5%23335%32%
2730
16th to endNight
22%14%5%8%6%3433422%
2912

Percentage Cloud Cover SE (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
16%13%5%7%6%4444426%
1552
16th to endDay
15%14%6%9%6%34346%26%
1719
February1st to 15thDay
16%12%6%7%5%25%446%27%
1788
16th to endDay
16%9%48%7%34346%31%
1580
March1st to 15thDay
17%12%46%5%24446%29%
1800
16th to endDay
17%10%46%6%245%47%29%
2222
April1st to 15thDay
18%9%35%5%24346%34%
2151
16th to endDay
19%7%25%5%335%46%35%
2211
May1st to 15thDay
19%8%45%43445%7%30%
2337
16th to endDay
14%6%35%5%25%45%7%39%
2617
June1st to 15thDay
11%425%5%35%46%8%43%
2520
16th to endDay
9%425%6%36%6%6%9%37%
2520
July1st to 15thDay
8%4245%35%5%6%8%45%
2520
16th to endDay
6%3145%46%5%7%9%43%
2655
August1st to 15thDay
6%425%5%3447%10%45%
2343
16th to endDay
8%5%245%36%5%5%8%44%
2292
September1st to 15thDay
11%424433446%50%
2145
16th to endDay
8%6%25%42446%7%48%
1980
October1st to 15thDay
16%6%24324446%42%
1887
16th to endDay
18%7%25%5%245%5%5%38%
1791
November1st to 15thDay
16%6%3442336%5%41%
1717
16th to endDay
18%9%46%413336%38%
1729
December1st to 15thDay
18%12%47%6%45%34429%
1560
16th to endDay
20%15%6%6%5%33445%23%
1664
January1st to 15thNight
16%11%46%6%24335%35%
2716
16th to endNight
14%12%6%8%6%25%435%30%
2857
February1st to 15thNight
17%12%445%24246%34%
2365
16th to endNight
16%9%45%5%25%445%34%
1893
March1st to 15thNight
18%10%45%5%3435%5%34%
2160
16th to endNight
16%8%35%6%3445%7%33%
2010
April1st to 15thNight
15%7%36%5%245%46%38%
1797
16th to endNight
20%6%25%42445%7%37%
1749
May1st to 15thNight
19%6%25%5%2435%9%34%
1610
16th to endNight
10%424425%46%9%44%
1496
June1st to 15thNight
10%5%3442435%6%49%
1440
16th to endNight
8%5%25%5%3446%9%44%
1440
July1st to 15thNight
7%324425%5%6%8%50%
1440
16th to endNight
4215%4235%6%9%54%
1513
August1st to 15thNight
441433445%10%53%
1612
16th to endNight
9%32342446%7%51%
1910
September1st to 15thNight
11%313322437%55%
1803
16th to endNight
7%4135%35%5%6%7%48%
1980
October1st to 15thNight
12%424423346%51%
2070
16th to endNight
18%7%35%413335%43%
2432
November1st to 15thNight
15%6%25%423435%45%
2471
16th to endNight
17%7%35%434346%39%
2561
December1st to 15thNight
18%10%48%6%23335%32%
2730
16th to endNight
22%14%5%9%6%3443322%
2912

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
59%411%14%9%
1553
16th to endDay
59%412%15%7%
1719
February1st to 15thDay
57%313%17%7%1
1790
16th to endDay
53%412%22%5%1
1580
March1st to 15thDay
54%414%19%6%
1800
16th to endDay
52%5%14%20%5%1
2223
April1st to 15thDay
51%311%21%12%
2151
16th to endDay
49%413%17%10%3
2211
May1st to 15thDay
51%5%12%22%7%
2337
16th to endDay
42%6%12%20%15%2
2621
June1st to 15thDay
37%5%11%26%17%1
2520
16th to endDay
39%7%13%21%16%1
2520
July1st to 15thDay
35%6%12%26%15%3
2371
16th to endDay
32%6%17%25%14%2
2488
August1st to 15thDay
32%5%15%27%18%1
2328
16th to endDay
36%5%12%25%17%3
2292
September1st to 15thDay
34%411%25%19%4
2145
16th to endDay
34%310%28%21%2
1980
October1st to 15thDay
41%411%26%14%2
1887
16th to endDay
46%312%23%12%1
1791
November1st to 15thDay
41%412%23%15%2
1717
16th to endDay
48%212%26%9%
1729
December1st to 15thDay
58%310%19%7%
1560
16th to endDay
63%5%11%13%6%
1664
January1st to 15thNight
51%411%18%12%
2716
16th to endNight
56%313%16%8%
2857
February1st to 15thNight
52%312%21%9%1
2374
16th to endNight
51%411%22%9%
1893
March1st to 15thNight
51%412%20%9%1
2160
16th to endNight
49%414%20%9%1
2010
April1st to 15thNight
46%411%20%14%2
1797
16th to endNight
46%410%21%12%4
1749
May1st to 15thNight
46%413%23%12%
1611
16th to endNight
34%7%15%21%18%3
1498
June1st to 15thNight
34%412%26%19%3
1440
16th to endNight
35%5%15%23%17%3
1440
July1st to 15thNight
30%7%12%27%18%3
1360
16th to endNight
24%5%15%30%18%4
1417
August1st to 15thNight
25%5%16%29%19%3
1603
16th to endNight
29%6%12%26%19%5%
1910
September1st to 15thNight
29%39%27%24%5%
1803
16th to endNight
31%5%10%27%22%3
1980
October1st to 15thNight
34%39%27%22%2
2070
16th to endNight
44%29%24%16%1
2432
November1st to 15thNight
41%38%24%16%4
2471
16th to endNight
46%212%25%12%
2561
December1st to 15thNight
55%311%19%9%
2730
16th to endNight
66%38%14%5%
2912

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
29%8%29%20%9%1
135
16th to endDay
19%13%36%22%6%
144
February1st to 15thDay
20%18%40%18%1
130
16th to endDay
16%11%35%24%11%1
81
March1st to 15thDay
31%18%30%16%3
90
16th to endDay
27%8%31%20%10%2
240
April1st to 15thDay
21%12%30%22%12%
270
16th to endDay
20%9%28%24%10%5%
270
May1st to 15thDay
23%9%26%24%10%4
294
16th to endDay
19%8%29%21%16%5%
517
June1st to 15thDay
11%425%32%20%5%
495
16th to endDay
10%7%31%28%16%5%
495
July1st to 15thDay
11%222%28%21%11%
475
16th to endDay
6%117%33%27%12%
515
August1st to 15thDay
8%213%31%25%18%
391
16th to endDay
10%213%28%28%15%
332
September1st to 15thDay
12%313%27%33%9%
315
16th to endDay
9%316%27%33%10%
314
October1st to 15thDay
21%423%23%22%3
222
16th to endDay
25%6%31%27%6%
144
November1st to 15thDay
15%8%28%22%17%8%
135
16th to endDay
31%7%36%14%10%
135
December1st to 15thDay
17%22%32%17%8%1
135
16th to endDay
24%18%46%6%3
144
January1st to 15thNight
22%12%37%20%6%
975
16th to endNight
20%12%35%27%3
1040
February1st to 15thNight
23%11%33%27%4
854
16th to endNight
21%9%35%26%6%
631
March1st to 15thNight
23%13%32%25%5%
720
16th to endNight
20%7%36%26%8%
618
April1st to 15thNight
20%11%33%27%6%
539
16th to endNight
23%432%28%9%
540
May1st to 15thNight
23%428%32%10%
540
16th to endNight
11%329%36%17%
563
June1st to 15thNight
14%223%45%13%
540
16th to endNight
9%224%44%18%1
540
July1st to 15thNight
9%117%42%26%2
510
16th to endNight
4113%46%31%2
564
August1st to 15thNight
6%8%47%32%4
539
16th to endNight
9%213%35%34%3
573
September1st to 15thNight
12%213%37%28%4
543
16th to endNight
9%417%34%30%3
717
October1st to 15thNight
15%6%23%32%20%
720
16th to endNight
22%10%32%24%9%
768
November1st to 15thNight
18%9%34%26%10%
760
16th to endNight
20%12%33%26%7%
806
December1st to 15thNight
25%11%33%23%6%
975
16th to endNight
29%10%33%22%4
1040
Page generated at 2018-02-15 09:58:44. Version ac04

Copyright 2018 A. Danko


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