Duck Lake
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Duck Lake clear sky chart from 2005-11-05 to 2019-06-24.

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
29%
17596
16%
53976
7%
17563
38%
17563
21%
33368

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
16%
1050
13%
3135
4%
1045
25%
1045
14%
2069
January16th to endNight
18%
899
18%
3139
8%
899
32%
899
16%
1889
February1st to 15thNight
22%
821
14%
2755
6%
818
33%
818
12%
1845
February16th to endNight
23%
736
14%
2292
7%
736
32%
736
13%
1546
March1st to 15thNight
23%
840
17%
2444
6%
840
35%
840
20%
1538
March16th to endNight
28%
896
11%
2464
1%
896
35%
896
16%
1696
April1st to 15thNight
25%
733
12%
2004
3%
733
32%
733
18%
1340
April16th to endNight
29%
624
14%
1872
8%
624
35%
624
19%
1232
May1st to 15thNight
39%
586
11%
1792
9%
586
43%
586
24%
1112
May16th to endNight
41%
439
9%
1533
8%
438
44%
438
17%
1034
June1st to 15thNight
37%
420
7%
1470
2%
420
42%
420
22%
888
June16th to endNight
41%
406
7%
1421
2%
406
45%
406
26%
794
July1st to 15thNight
54%
370
14%
1295
8%
370
61%
370
43%
592
July16th to endNight
58%
408
21%
1446
22%
386
68%
386
44%
629
August1st to 15thNight
60%
492
23%
1637
22%
490
67%
490
46%
766
August16th to endNight
50%
621
27%
1863
18%
621
57%
621
42%
966
September1st to 15thNight
49%
717
21%
1991
13%
717
54%
717
36%
1157
September16th to endNight
40%
776
22%
2145
11%
776
50%
776
31%
1298
October1st to 15thNight
32%
780
17%
2268
8%
780
41%
780
20%
1447
October16th to endNight
28%
832
21%
2690
8%
832
43%
832
21%
1566
November1st to 15thNight
15%
930
18%
2775
4%
930
29%
930
16%
1701
November16th to endNight
17%
1050
15%
3035
3%
1050
28%
1050
16%
1946
December1st to 15thNight
22%
1050
17%
3150
7%
1050
31%
1050
17%
2084
December16th to endNight
15%
1120
13%
3360
3%
1120
26%
1120
13%
2233

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
7%7%25%5%35%5%6%8%42%
54873
Night
5%6%35%5%345%6%8%46%
54131
Cloud CoverDay
7%7%35%5%345%6%8%42%
54874
Night
5%6%36%5%2446%8%46%
54134
TransparencyDay
38%8%16%22%11%2
54532
Night
34%8%19%24%11%2
53976
SeeingDay
19%20%27%20%9%2
8195
Night
15%20%28%23%9%1
17600

By Month

Percentage Cloud Cover NW (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
15%37%5%5%6%5%7%10%42%
1473
16th to endDay
17%49%7%46%6%6%10%36%
1792
February1st to 15thDay
28%48%6%45%6%5%10%37%
1767
16th to endDay
18%5%11%7%35%5%5%10%34%
1751
March1st to 15thDay
25%37%5%35%5%7%10%42%
2175
16th to endDay
5%11%48%6%346%6%9%32%
2463
April1st to 15thDay
7%12%5%7%5%35%6%7%8%29%
2600
16th to endDay
8%15%36%5%345%6%7%35%
2693
May1st to 15thDay
10%10%25%5%35%5%5%7%39%
2815
16th to endDay
25%8%35%5%35%447%26%
3282
June1st to 15thDay
14%5%25%5%345%6%7%37%
3150
16th to endDay
9%4246%45%5%7%8%41%
3047
July1st to 15thDay
5%213436%6%5%7%53%
2925
16th to endDay
42232345%6%62%
2980
August1st to 15thDay
8%31342446%6%53%
2567
16th to endDay
8%314324447%55%
2691
September1st to 15thDay
11%5%14424446%51%
2298
16th to endDay
11%414424348%49%
2145
October1st to 15thDay
10%9%45%5%23448%40%
2022
16th to endDay
47%15%4246%8%8%44%
1885
November1st to 15thDay
37%35%5%35%47%9%44%
1729
16th to endDay
28%46%5%35%45%11%41%
1585
December1st to 15thDay
16%48%5%36%6%8%12%37%
1470
16th to endDay
17%38%5%35%6%7%9%39%
1568
January1st to 15thNight
16%37%6%35%7%6%10%40%
3135
16th to endNight
16%37%5%245%6%9%46%
3139
February1st to 15thNight
28%48%6%35%6%6%8%38%
2744
16th to endNight
18%48%8%45%6%7%8%36%
2292
March1st to 15thNight
15%35%435%5%7%12%45%
2444
16th to endNight
5%8%46%445%6%6%9%38%
2461
April1st to 15thNight
6%8%45%425%5%6%9%40%
2004
16th to endNight
7%11%36%5%24446%43%
1872
May1st to 15thNight
7%8%244346%5%7%43%
1791
16th to endNight
19%7%2432446%6%36%
1533
June1st to 15thNight
13%5%134245%47%45%
1470
16th to endNight
9%3234245%5%8%49%
1421
July1st to 15thNight
4212212347%66%
1365
16th to endNight
3112222245%69%
1538
August1st to 15thNight
6%21221236%8%62%
1645
16th to endNight
7%213323246%62%
1863
September1st to 15thNight
8%5%12323345%56%
1991
16th to endNight
9%4233235%6%8%49%
2145
October1st to 15thNight
9%9%24324449%44%
2268
16th to endNight
45%25%42446%8%50%
2690
November1st to 15thNight
46%35%43446%8%48%
2775
16th to endNight
26%37%6%25%46%11%43%
3035
December1st to 15thNight
17%37%5%25%6%6%10%41%
3150
16th to endNight
26%5%8%7%45%5%7%8%38%
3360

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
16%37%6%46%46%10%42%
1473
16th to endDay
17%49%7%45%5%7%9%37%
1792
February1st to 15thDay
28%5%7%6%45%46%11%36%
1767
16th to endDay
29%5%10%7%3446%8%36%
1751
March1st to 15thDay
26%37%6%345%7%9%42%
2175
16th to endDay
5%11%5%7%6%25%5%6%9%32%
2464
April1st to 15thDay
8%12%5%6%5%35%5%6%8%31%
2600
16th to endDay
7%14%36%5%3446%7%35%
2693
May1st to 15thDay
10%10%25%6%3445%7%40%
2815
16th to endDay
24%9%25%5%345%46%27%
3282
June1st to 15thDay
14%6%25%5%35%5%5%8%37%
3150
16th to endDay
9%5%24446%5%7%9%41%
3047
July1st to 15thDay
4313435%5%6%7%53%
2925
16th to endDay
42232445%6%62%
2980
August1st to 15thDay
7%3144335%5%7%53%
2567
16th to endDay
7%31342346%7%55%
2691
September1st to 15thDay
10%5%24423445%52%
2298
16th to endDay
11%5%14423446%49%
2145
October1st to 15thDay
9%10%35%6%33447%41%
2022
16th to endDay
47%25%435%5%6%10%44%
1885
November1st to 15thDay
48%35%6%245%6%8%44%
1729
16th to endDay
28%46%6%2446%11%41%
1585
December1st to 15thDay
16%310%5%36%7%8%9%38%
1470
16th to endDay
17%5%8%6%25%7%7%8%39%
1568
January1st to 15thNight
16%37%6%36%5%7%10%40%
3135
16th to endNight
16%37%5%25%5%6%9%44%
3139
February1st to 15thNight
28%48%7%25%5%6%9%37%
2744
16th to endNight
18%49%9%45%5%6%8%36%
2292
March1st to 15thNight
15%36%5%345%6%11%45%
2444
16th to endNight
5%8%47%426%5%6%9%38%
2464
April1st to 15thNight
7%9%36%5%25%46%8%39%
2004
16th to endNight
7%11%35%5%24445%44%
1872
May1st to 15thNight
7%7%35%4245%6%7%44%
1791
16th to endNight
20%6%243345%5%7%36%
1533
June1st to 15thNight
12%5%133245%6%7%46%
1470
16th to endNight
9%323425%5%48%49%
1421
July1st to 15thNight
4212312347%66%
1365
16th to endNight
422323245%69%
1538
August1st to 15thNight
6%21221236%9%62%
1645
16th to endNight
5%31332325%7%61%
1863
September1st to 15thNight
8%6%13323346%56%
1991
16th to endNight
9%5%133345%6%8%49%
2145
October1st to 15thNight
9%10%2432345%8%43%
2268
16th to endNight
45%35%4235%5%8%51%
2690
November1st to 15thNight
47%35%33346%8%48%
2775
16th to endNight
26%37%6%3346%11%43%
3035
December1st to 15thNight
16%47%6%26%5%7%8%41%
3150
16th to endNight
27%410%7%445%7%8%37%
3360

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
36%12%22%21%5%2
1473
16th to endDay
40%10%17%20%7%2
1792
February1st to 15thDay
41%10%23%17%5%1
1767
16th to endDay
45%7%18%18%8%1
1751
March1st to 15thDay
35%12%21%22%7%
2175
16th to endDay
46%10%18%19%5%
2464
April1st to 15thDay
50%9%16%17%6%
2600
16th to endDay
47%7%18%18%7%1
2693
May1st to 15thDay
43%8%17%22%8%
2815
16th to endDay
58%6%14%14%5%
3287
June1st to 15thDay
43%8%15%20%10%
3150
16th to endDay
36%9%17%25%9%
3047
July1st to 15thDay
27%6%13%26%21%5%
2766
16th to endDay
19%6%10%26%27%9%
2809
August1st to 15thDay
28%7%12%29%17%4
2550
16th to endDay
26%5%12%29%21%3
2691
September1st to 15thDay
34%5%10%27%16%5%
2298
16th to endDay
35%6%13%26%13%3
2145
October1st to 15thDay
42%7%20%20%8%
2022
16th to endDay
33%10%17%26%10%
1885
November1st to 15thDay
35%10%23%21%7%
1729
16th to endDay
36%10%23%18%8%1
1585
December1st to 15thDay
35%14%20%20%6%1
1470
16th to endDay
38%11%19%20%9%
1568
January1st to 15thNight
36%12%22%18%7%2
3135
16th to endNight
33%10%20%22%10%2
3139
February1st to 15thNight
41%11%18%18%8%1
2755
16th to endNight
43%9%15%18%10%1
2292
March1st to 15thNight
32%10%23%24%8%
2444
16th to endNight
40%10%20%21%7%
2464
April1st to 15thNight
40%7%19%25%6%
2004
16th to endNight
41%7%17%23%8%
1872
May1st to 15thNight
36%6%20%25%10%
1792
16th to endNight
46%7%18%19%6%
1533
June1st to 15thNight
36%7%18%26%10%
1470
16th to endNight
32%6%19%29%12%1
1421
July1st to 15thNight
18%411%36%20%7%
1295
16th to endNight
17%49%28%28%10%
1446
August1st to 15thNight
18%414%39%16%4
1637
16th to endNight
22%411%31%25%4
1863
September1st to 15thNight
28%6%11%29%17%6%
1991
16th to endNight
30%7%17%25%14%4
2145
October1st to 15thNight
38%6%19%24%8%1
2268
16th to endNight
30%8%19%27%12%1
2690
November1st to 15thNight
33%8%24%23%9%1
2775
16th to endNight
34%11%23%22%7%1
3035
December1st to 15thNight
36%11%19%21%8%2
3150
16th to endNight
40%9%20%20%8%
3360

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
16%10%26%17%22%6%
120
16th to endDay
13%30%35%15%22
128
February1st to 15thDay
17%22%33%21%5%
158
16th to endDay
14%29%33%16%41
254
March1st to 15thDay
20%32%26%12%42
390
16th to endDay
27%25%29%10%5%2
416
April1st to 15thDay
26%31%27%11%2
389
16th to endDay
27%20%24%17%6%2
378
May1st to 15thDay
25%20%22%20%8%2
460
16th to endDay
31%10%16%21%17%2
677
June1st to 15thDay
21%20%23%21%9%2
645
16th to endDay
16%16%28%23%11%2
611
July1st to 15thDay
9%13%29%29%15%2
550
16th to endDay
6%13%36%25%13%3
489
August1st to 15thDay
7%15%30%28%14%3
359
16th to endDay
12%16%29%28%9%4
396
September1st to 15thDay
18%19%31%20%6%3
375
16th to endDay
21%22%29%18%6%2
375
October1st to 15thDay
29%17%30%15%6%1
252
16th to endDay
20%21%25%17%10%4
192
November1st to 15thDay
24%24%33%13%3
180
16th to endDay
23%29%21%17%5%1
153
December1st to 15thDay
22%19%26%22%5%4
120
16th to endDay
21%25%25%14%7%5%
128
January1st to 15thNight
21%28%29%15%5%
1050
16th to endNight
16%28%33%16%41
899
February1st to 15thNight
15%24%29%21%7%2
824
16th to endNight
12%22%32%24%9%
736
March1st to 15thNight
14%23%32%20%6%1
840
16th to endNight
17%21%25%25%7%1
896
April1st to 15thNight
15%21%29%23%8%
733
16th to endNight
16%19%30%22%11%
624
May1st to 15thNight
14%14%23%31%13%2
587
16th to endNight
24%7%17%27%20%2
439
June1st to 15thNight
17%15%23%26%14%1
420
16th to endNight
13%13%27%28%16%
406
July1st to 15thNight
7%9%26%38%18%1
370
16th to endNight
5%6%25%39%21%1
408
August1st to 15thNight
6%424%39%23%2
492
16th to endNight
8%10%27%35%16%2
621
September1st to 15thNight
11%9%24%30%18%5%
717
16th to endNight
14%13%26%28%13%3
776
October1st to 15thNight
20%17%22%26%10%2
780
16th to endNight
16%22%27%23%7%1
832
November1st to 15thNight
24%28%27%15%2
930
16th to endNight
18%29%32%15%4
1050
December1st to 15thNight
14%25%32%20%41
1050
16th to endNight
17%27%32%15%6%
1120
Page generated at 2019-06-24 18:41:29. Version ac04

Copyright 2019 A. Danko


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