North Frontenac Dark Sky Preserve
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the North Frontenac Dark Sky Preserve clear sky chart from 2005-11-05 to 2017-08-12.

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
27%
14556
14%
46511
8%
14527
35%
14527
17%
32592

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
13%
720
7%
2506
2%
716
19%
716
7%
1988
January16th to endNight
18%
768
12%
2592
5%
768
26%
768
11%
1938
February1st to 15thNight
15%
702
10%
2287
3%
701
24%
701
11%
1711
February16th to endNight
18%
631
15%
1976
5%
631
30%
631
14%
1426
March1st to 15thNight
17%
720
14%
2057
6%
720
26%
720
16%
1503
March16th to endNight
28%
768
20%
2064
9%
768
37%
768
23%
1384
April1st to 15thNight
21%
718
16%
1796
5%
718
28%
718
21%
1300
April16th to endNight
30%
643
18%
1723
7%
643
36%
643
23%
1197
May1st to 15thNight
34%
372
18%
1452
15%
372
45%
372
19%
918
May16th to endNight
34%
374
15%
1497
10%
374
48%
374
20%
904
June1st to 15thNight
32%
360
9%
1440
7%
360
43%
360
16%
948
June16th to endNight
41%
360
9%
1440
12%
360
47%
360
18%
911
July1st to 15thNight
47%
340
15%
1360
20%
340
53%
340
28%
742
July16th to endNight
53%
376
14%
1418
14%
354
59%
354
28%
788
August1st to 15thNight
50%
488
15%
1537
11%
486
54%
486
29%
937
August16th to endNight
49%
627
20%
1677
9%
627
55%
627
37%
1018
September1st to 15thNight
42%
660
18%
1650
7%
660
47%
660
30%
1108
September16th to endNight
45%
657
21%
1807
13%
657
51%
657
31%
1150
October1st to 15thNight
31%
660
17%
1980
11%
660
39%
660
19%
1377
October16th to endNight
20%
704
10%
2163
4%
704
28%
704
12%
1657
November1st to 15thNight
26%
700
18%
2361
13%
700
36%
700
17%
1626
November16th to endNight
19%
720
11%
2520
7%
720
26%
720
10%
1922
December1st to 15thNight
16%
720
6%
2520
2%
720
21%
720
8%
1993
December16th to endNight
11%
768
9%
2688
3%
768
18%
768
8%
2146

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
17%9%37%6%34446%31%
47473
Night
16%9%46%5%3445%6%33%
46681
Cloud CoverDay
17%9%36%6%34446%31%
47483
Night
16%9%36%5%3445%6%33%
46686
TransparencyDay
52%5%11%18%10%1
47161
Night
50%5%12%19%10%
46511
SeeingDay
22%13%30%19%9%3
5290
Night
22%13%31%23%8%
14559

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
20%16%6%8%6%23336%22%
1432
16th to endDay
15%15%6%10%8%35%335%21%
1631
February1st to 15thDay
14%15%6%10%7%35%445%22%
1575
16th to endDay
18%15%47%6%24346%27%
1496
March1st to 15thDay
15%12%5%8%8%45%44327%
1891
16th to endDay
15%8%46%43334440%
2160
April1st to 15thDay
21%10%35%433345%32%
2152
16th to endDay
20%8%35%424346%37%
2247
May1st to 15thDay
19%8%37%4245%47%32%
2499
16th to endDay
15%5%36%6%4445%7%36%
2618
June1st to 15thDay
21%7%36%5%35%45%7%29%
2520
16th to endDay
16%6%36%5%35%5%6%8%32%
2520
July1st to 15thDay
13%5%25%6%36%5%6%8%35%
2520
16th to endDay
11%6%35%6%46%5%6%8%34%
2654
August1st to 15thDay
12%6%38%6%45%5%5%8%34%
2324
16th to endDay
14%5%25%6%445%5%7%36%
2162
September1st to 15thDay
16%7%25%5%33347%39%
1980
16th to endDay
16%6%345%33446%42%
1821
October1st to 15thDay
22%9%27%5%33347%31%
1650
16th to endDay
27%11%36%6%45%335%23%
1708
November1st to 15thDay
15%8%38%435%6%45%34%
1497
16th to endDay
23%12%5%7%5%34346%22%
1440
December1st to 15thDay
22%16%5%10%6%3443318%
1440
16th to endDay
22%17%5%8%5%33336%19%
1536
January1st to 15thNight
19%13%6%10%7%45%44419%
2506
16th to endNight
12%15%5%9%7%34446%26%
2592
February1st to 15thNight
13%14%6%8%6%35%5%5%6%23%
2285
16th to endNight
14%12%5%6%6%3445%6%29%
1976
March1st to 15thNight
17%12%36%6%34346%31%
2045
16th to endNight
14%7%35%5%3434442%
2064
April1st to 15thNight
20%9%445%23346%35%
1796
16th to endNight
15%9%25%43345%7%39%
1723
May1st to 15thNight
19%6%35%32245%7%37%
1452
16th to endNight
13%6%35%5%3445%8%41%
1495
June1st to 15thNight
16%6%36%5%3435%8%34%
1440
16th to endNight
13%5%35%5%35%5%7%7%36%
1440
July1st to 15thNight
8%324435%447%49%
1440
16th to endNight
8%2244345%7%9%46%
1514
August1st to 15thNight
8%6%25%43347%7%44%
1547
16th to endNight
8%5%15%423446%52%
1677
September1st to 15thNight
14%5%145%2445%6%43%
1650
16th to endNight
17%424313345%48%
1807
October1st to 15thNight
21%7%35%5%23347%34%
1980
16th to endNight
24%11%35%6%34446%25%
2163
November1st to 15thNight
16%10%36%5%345%5%6%33%
2361
16th to endNight
23%11%46%5%25%445%24%
2520
December1st to 15thNight
21%16%48%5%24446%21%
2520
16th to endNight
22%14%6%8%7%3434420%
2688

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
20%16%5%8%6%23345%23%
1432
16th to endDay
14%15%6%11%7%4443422%
1631
February1st to 15thDay
14%15%6%10%7%35%445%22%
1575
16th to endDay
18%15%5%7%6%3334427%
1496
March1st to 15thDay
15%12%5%8%8%45%43327%
1902
16th to endDay
15%9%35%5%24435%40%
2159
April1st to 15thDay
22%10%35%434345%32%
2152
16th to endDay
20%9%35%434345%37%
2247
May1st to 15thDay
19%7%46%5%24447%32%
2499
16th to endDay
15%6%25%7%35%35%7%36%
2618
June1st to 15thDay
21%7%36%5%25%5%5%7%29%
2520
16th to endDay
16%6%36%6%35%5%6%7%32%
2520
July1st to 15thDay
12%6%25%6%36%5%6%8%35%
2520
16th to endDay
12%5%36%6%46%5%6%8%34%
2654
August1st to 15thDay
12%6%37%7%35%5%5%8%33%
2324
16th to endDay
14%5%25%6%45%5%5%7%36%
2162
September1st to 15thDay
16%6%25%5%2335%6%39%
1980
16th to endDay
17%6%25%433346%41%
1821
October1st to 15thDay
21%8%37%5%33346%31%
1650
16th to endDay
27%10%36%6%44335%24%
1708
November1st to 15thDay
15%8%47%5%35%6%5%5%34%
1497
16th to endDay
23%13%48%5%34346%22%
1440
December1st to 15thDay
22%16%5%9%6%3443318%
1440
16th to endDay
22%17%6%8%5%33335%19%
1536
January1st to 15thNight
19%13%6%10%7%34445%18%
2506
16th to endNight
13%15%5%9%6%3435%5%26%
2592
February1st to 15thNight
12%14%5%9%6%35%5%5%6%23%
2278
16th to endNight
14%12%47%6%3445%7%29%
1976
March1st to 15thNight
18%11%46%6%34336%31%
2057
16th to endNight
14%7%35%5%35%33442%
2064
April1st to 15thNight
20%8%44423445%35%
1796
16th to endNight
16%8%25%5%33447%38%
1723
May1st to 15thNight
20%7%35%32345%6%37%
1452
16th to endNight
13%5%345%34448%41%
1495
June1st to 15thNight
16%7%35%5%4435%8%34%
1440
16th to endNight
13%5%35%5%26%5%7%7%36%
1440
July1st to 15thNight
9%324435%45%6%49%
1440
16th to endNight
9%32443447%9%46%
1514
August1st to 15thNight
9%6%25%43446%7%45%
1547
16th to endNight
8%5%25%424348%50%
1677
September1st to 15thNight
15%5%1443445%6%43%
1650
16th to endNight
17%424323345%48%
1807
October1st to 15thNight
21%7%25%5%2435%6%34%
1980
16th to endNight
24%10%36%5%3445%6%25%
2163
November1st to 15thNight
15%9%46%4345%5%5%34%
2361
16th to endNight
22%12%46%5%35%45%5%24%
2520
December1st to 15thNight
21%16%5%7%6%34446%21%
2520
16th to endNight
23%14%5%9%6%2434420%
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
64%49%13%7%1
1433
16th to endDay
65%47%11%8%1
1631
February1st to 15thDay
64%410%14%5%
1577
16th to endDay
60%311%12%11%1
1496
March1st to 15thDay
61%410%15%6%1
1902
16th to endDay
46%39%19%15%5%
2160
April1st to 15thDay
54%47%17%13%2
2152
16th to endDay
48%38%19%16%2
2247
May1st to 15thDay
50%5%10%16%14%2
2499
16th to endDay
46%6%12%20%12%1
2622
June1st to 15thDay
52%6%10%19%9%
2520
16th to endDay
47%7%12%19%11%
2520
July1st to 15thDay
41%7%13%26%10%
2371
16th to endDay
45%7%14%22%9%
2487
August1st to 15thDay
46%7%15%21%9%
2310
16th to endDay
44%6%15%23%9%
2162
September1st to 15thDay
44%412%25%11%
1980
16th to endDay
43%5%10%30%10%
1821
October1st to 15thDay
52%5%10%19%10%1
1650
16th to endDay
63%5%9%15%5%
1708
November1st to 15thDay
49%6%16%17%9%
1497
16th to endDay
62%5%10%12%6%1
1440
December1st to 15thDay
69%5%12%10%3
1440
16th to endDay
66%5%10%10%6%
1536
January1st to 15thNight
66%5%11%11%4
2506
16th to endNight
59%5%10%16%8%
2592
February1st to 15thNight
57%6%14%15%5%
2287
16th to endNight
52%5%11%18%10%
1976
March1st to 15thNight
54%411%19%9%
2057
16th to endNight
43%410%21%16%2
2064
April1st to 15thNight
49%48%20%15%1
1796
16th to endNight
44%6%8%19%17%2
1723
May1st to 15thNight
45%410%21%14%3
1452
16th to endNight
40%6%12%22%15%2
1497
June1st to 15thNight
47%6%13%20%11%
1440
16th to endNight
43%7%13%22%12%
1440
July1st to 15thNight
32%5%13%29%16%1
1360
16th to endNight
31%7%18%26%14%
1418
August1st to 15thNight
35%6%17%26%12%
1537
16th to endNight
31%5%16%32%12%
1677
September1st to 15thNight
39%6%14%28%10%
1650
16th to endNight
38%412%34%9%
1807
October1st to 15thNight
49%5%12%20%12%
1980
16th to endNight
58%6%13%15%6%
2163
November1st to 15thNight
49%5%13%17%11%1
2361
16th to endNight
59%6%11%16%4
2520
December1st to 15thNight
64%6%13%12%3
2520
16th to endNight
66%5%10%11%6%
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
33%26%18%15%6%
60
16th to endDay
45%12%31%8%2
80
February1st to 15thDay
34%27%33%4
90
16th to endDay
36%16%31%13%2
155
March1st to 15thDay
25%18%32%19%4
270
16th to endDay
25%16%34%13%8%1
288
April1st to 15thDay
28%22%26%14%7%
270
16th to endDay
25%20%25%15%8%3
270
May1st to 15thDay
28%14%27%16%7%4
288
16th to endDay
17%15%36%17%11%1
331
June1st to 15thDay
25%12%31%20%9%1
315
16th to endDay
15%13%34%23%9%2
315
July1st to 15thDay
14%7%31%29%13%3
305
16th to endDay
15%7%35%22%13%4
326
August1st to 15thDay
14%5%28%32%11%6%
297
16th to endDay
15%229%28%15%8%
268
September1st to 15thDay
18%7%25%20%15%11%
255
16th to endDay
19%9%28%22%11%7%
254
October1st to 15thDay
23%16%27%17%11%2
255
16th to endDay
33%16%29%17%2
263
November1st to 15thDay
19%9%37%22%9%1
151
16th to endDay
28%16%35%11%6%1
60
December1st to 15thDay
25%31%25%16%1
60
16th to endDay
40%26%31%1
64
January1st to 15thNight
28%18%31%15%4
720
16th to endNight
22%16%36%19%4
768
February1st to 15thNight
20%20%38%17%2
704
16th to endNight
20%19%38%17%3
631
March1st to 15thNight
26%16%34%20%2
720
16th to endNight
19%15%32%22%9%1
768
April1st to 15thNight
25%16%32%20%4
718
16th to endNight
20%16%29%23%9%
643
May1st to 15thNight
23%9%27%30%7%1
372
16th to endNight
14%8%38%27%10%
375
June1st to 15thNight
18%10%31%29%9%1
360
16th to endNight
16%5%29%36%11%
360
July1st to 15thNight
7%431%37%17%
340
16th to endNight
9%130%42%14%
376
August1st to 15thNight
13%226%34%20%2
488
16th to endNight
10%430%32%19%2
627
September1st to 15thNight
16%6%29%26%18%2
660
16th to endNight
20%8%22%26%19%2
657
October1st to 15thNight
26%11%27%22%11%1
660
16th to endNight
30%13%30%19%6%
704
November1st to 15thNight
22%14%31%20%9%1
700
16th to endNight
32%16%26%17%7%
720
December1st to 15thNight
29%18%30%17%3
720
16th to endNight
32%14%34%15%2
768
Page generated at 2017-08-13 14:16:47. Version ac04

Copyright 2017 A. Danko


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