North Glengarry
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the North Glengarry clear sky chart from 2005-11-06 to 2024-02-05.

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
28%
22638
14%
80463
8%
22553
36%
22553
15%
56833

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
13%
754
7%
4400
2%
737
20%
737
5%
3240
January11th to 20thNight
16%
757
8%
4398
4%
740
25%
740
5%
3305
January21st to endNight
20%
829
7%
4846
7%
814
30%
814
7%
3674
February1st to 10thNight
16%
739
11%
2399
3%
739
25%
739
11%
1862
February11th to 20thNight
17%
702
13%
2221
5%
700
29%
700
14%
1632
February21st to endNight
21%
592
16%
1776
7%
592
32%
592
15%
1299
March1st to 10thNight
20%
720
15%
2160
8%
720
29%
720
14%
1608
March11th to 20thNight
20%
720
16%
2040
6%
720
30%
720
16%
1483
March21st to endNight
28%
792
21%
2019
9%
792
35%
792
21%
1451
April1st to 10thNight
22%
720
16%
1800
5%
720
28%
720
20%
1343
April11th to 20thNight
23%
711
17%
1775
4%
711
31%
711
21%
1295
April21st to endNight
25%
622
17%
1702
6%
622
33%
622
20%
1208
May1st to 10thNight
30%
362
17%
1442
13%
362
41%
362
17%
944
May11th to 20thNight
32%
354
21%
1416
16%
354
49%
354
19%
874
May21st to endNight
34%
389
14%
1551
12%
388
47%
388
21%
922
June1st to 10thNight
36%
360
11%
1440
10%
360
46%
360
16%
950
June11th to 20thNight
39%
360
13%
1440
15%
360
48%
360
21%
871
June21st to endNight
40%
360
11%
1440
16%
360
47%
360
19%
916
July1st to 10thNight
50%
350
15%
1400
20%
350
58%
350
26%
775
July11th to 20thNight
49%
348
17%
1392
22%
348
56%
348
25%
803
July21st to endNight
46%
394
15%
1486
16%
372
52%
372
25%
849
August1st to 10thNight
52%
358
17%
1422
18%
356
58%
356
26%
801
August11th to 20thNight
54%
556
18%
1620
11%
556
58%
556
31%
1014
August21st to endNight
46%
792
18%
1980
8%
792
50%
792
33%
1311
September1st to 10thNight
46%
720
17%
1800
7%
720
49%
720
31%
1200
September11th to 20thNight
49%
720
22%
1840
13%
720
53%
720
35%
1162
September21st to endNight
42%
720
23%
1980
15%
720
49%
720
29%
1298
October1st to 10thNight
33%
720
18%
2151
11%
720
42%
720
22%
1464
October11th to 20thNight
27%
720
16%
2160
8%
720
37%
720
18%
1545
October21st to endNight
23%
792
13%
2569
7%
792
33%
792
15%
1892
November1st to 10thNight
27%
740
16%
2407
9%
740
37%
740
17%
1652
November11th to 20thNight
20%
760
17%
2588
10%
760
31%
760
15%
1813
November21st to endNight
19%
760
11%
2660
5%
760
27%
760
11%
1972
December1st to 10thNight
15%
760
9%
2660
3%
760
22%
760
8%
2127
December11th to 20thNight
15%
760
12%
3244
5%
759
25%
759
8%
2456
December21st to endNight
12%
825
6%
4839
2%
817
20%
817
5%
3822

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
18%10%47%6%35%5%5%6%32%
78035
Night
19%11%47%6%34446%31%
80804
TransparencyDay
53%311%21%11%1
77740
Night
56%311%20%10%1
80633
SeeingDay
23%16%29%21%9%2
13471
Night
23%12%30%25%9%1
22666

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 10thDay
17%17%5%11%6%4443423%
2517
11th to 20thDay
14%13%8%10%8%46%5%5%5%23%
2520
21st to endDay
15%19%7%8%7%5%45%5%5%19%
2786
February1st to 10thDay
16%16%5%11%6%345%5%5%24%
1656
11th to 20thDay
16%14%5%9%7%34446%27%
1627
21st to endDay
20%14%6%8%5%45%44425%
1480
March1st to 10thDay
16%13%5%10%7%4444429%
1797
11th to 20thDay
18%12%47%6%35%35%5%32%
1916
21st to endDay
21%11%36%5%24445%36%
2336
April1st to 10thDay
23%11%46%5%24335%33%
2160
11th to 20thDay
21%9%47%5%23446%36%
2134
21st to endDay
24%9%46%6%34445%31%
2271
May1st to 10thDay
22%7%37%5%35%5%45%35%
2520
11th to 20thDay
18%7%36%5%34446%39%
2478
21st to endDay
18%6%26%6%445%6%8%36%
2725
June1st to 10thDay
24%8%35%6%345%5%8%29%
2520
11th to 20thDay
16%6%35%5%45%5%6%8%37%
2520
21st to endDay
20%7%26%5%36%6%5%8%31%
2520
July1st to 10thDay
13%6%36%6%35%45%9%40%
2520
11th to 20thDay
13%6%26%5%36%6%7%9%36%
2520
21st to endDay
13%5%35%5%46%5%7%9%38%
2744
August1st to 10thDay
13%7%26%6%35%6%7%8%38%
2506
11th to 20thDay
12%5%26%5%35%6%7%8%40%
2258
21st to endDay
14%6%26%5%35%5%5%8%40%
2376
September1st to 10thDay
15%5%25%4345%6%7%42%
2160
11th to 20thDay
15%425%32445%7%47%
2120
21st to endDay
19%7%25%42445%7%41%
1980
October1st to 10thDay
22%7%35%4345%6%5%36%
1805
11th to 20thDay
22%10%48%6%44446%29%
1800
21st to endDay
27%11%35%5%35%45%5%27%
1787
November1st to 10thDay
17%8%5%7%6%35%5%5%6%33%
1671
11th to 20thDay
19%12%47%6%445%5%6%28%
1587
21st to endDay
21%14%48%7%45%5%5%6%22%
1520
December1st to 10thDay
25%15%6%8%6%46%5%4417%
1520
11th to 20thDay
22%15%6%9%5%34446%23%
1906
21st to endDay
28%18%5%8%6%2333320%
2772
January1st to 10thNight
18%17%6%10%6%35%445%22%
4429
11th to 20thNight
13%15%6%12%8%5%5%5%5%5%20%
4440
21st to endNight
17%18%7%9%8%44335%22%
4855
February1st to 10thNight
16%13%6%10%9%5%5%5%5%5%22%
2399
11th to 20thNight
15%12%5%9%7%45%5%45%28%
2219
21st to endNight
16%14%6%9%6%34445%30%
1776
March1st to 10thNight
17%13%5%9%7%45%445%28%
2150
11th to 20thNight
18%14%47%6%34445%32%
2040
21st to endNight
18%10%47%6%34345%38%
2019
April1st to 10thNight
24%9%46%5%4435%6%32%
1800
11th to 20thNight
23%8%36%5%24345%35%
1775
21st to endNight
23%9%36%6%34446%33%
1702
May1st to 10thNight
23%8%25%4346%5%6%35%
1442
11th to 20thNight
19%7%35%424447%40%
1415
21st to endNight
15%5%25%5%35%5%5%8%42%
1550
June1st to 10thNight
20%6%25%6%5%5%5%6%9%30%
1440
11th to 20thNight
18%5%35%5%345%5%7%40%
1440
21st to endNight
17%7%36%5%45%5%6%7%36%
1440
July1st to 10thNight
10%425%5%36%5%6%9%45%
1440
11th to 20thNight
12%5%26%6%35%5%7%10%41%
1440
21st to endNight
11%5%35%5%35%5%7%8%42%
1574
August1st to 10thNight
11%5%26%6%245%6%10%42%
1432
11th to 20thNight
12%5%26%4445%5%7%45%
1620
21st to endNight
13%5%35%5%35%46%8%42%
1980
September1st to 10thNight
12%5%36%7%35%5%5%7%43%
1800
11th to 20thNight
16%5%25%42335%7%48%
1840
21st to endNight
18%5%25%5%35%5%37%43%
1980
October1st to 10thNight
21%7%26%5%3445%6%37%
2151
11th to 20thNight
21%9%47%6%35%5%46%32%
2160
21st to endNight
25%10%46%6%34445%29%
2569
November1st to 10thNight
21%9%37%5%3345%6%34%
2407
11th to 20thNight
18%10%48%6%345%5%6%31%
2588
21st to endNight
22%13%5%8%7%34446%24%
2660
December1st to 10thNight
21%16%6%9%7%45%5%45%18%
2660
11th to 20thNight
23%15%5%8%6%3444425%
3288
21st to endNight
31%16%48%5%2334320%
4884

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
67%113%13%5%1
2518
11th to 20thDay
64%111%15%8%1
2520
21st to endDay
67%313%11%5%1
2786
February1st to 10thDay
64%29%19%5%2
1656
11th to 20thDay
60%311%18%8%1
1636
21st to endDay
63%29%14%10%1
1480
March1st to 10thDay
60%29%17%10%1
1800
11th to 20thDay
56%211%15%13%3
1916
21st to endDay
53%27%19%15%4
2336
April1st to 10thDay
56%26%20%13%3
2160
11th to 20thDay
52%26%22%17%2
2134
21st to endDay
57%28%16%13%4
2271
May1st to 10thDay
52%36%21%16%2
2520
11th to 20thDay
47%38%23%16%3
2482
21st to endDay
47%313%21%14%2
2725
June1st to 10thDay
54%310%20%12%1
2520
11th to 20thDay
45%311%25%13%3
2520
21st to endDay
51%414%20%10%1
2520
July1st to 10thDay
41%412%29%14%1
2450
11th to 20thDay
42%414%30%10%
2445
21st to endDay
42%416%27%11%
2591
August1st to 10thDay
42%417%28%9%
2492
11th to 20thDay
40%418%27%11%
2258
21st to endDay
42%313%28%13%1
2376
September1st to 10thDay
40%314%29%13%
2160
11th to 20thDay
36%311%33%15%1
2120
21st to endDay
44%314%29%10%
1980
October1st to 10thDay
50%39%26%12%
1805
11th to 20thDay
59%212%19%8%
1800
21st to endDay
60%211%18%8%1
1787
November1st to 10thDay
52%313%23%9%1
1671
11th to 20thDay
57%311%17%11%1
1587
21st to endDay
63%413%14%5%
1520
December1st to 10thDay
69%412%12%3
1520
11th to 20thDay
65%313%15%4
1906
21st to endDay
72%28%14%4
2772
January1st to 10thNight
67%215%12%4
4429
11th to 20thNight
68%211%13%5%
4440
21st to endNight
67%212%13%6%1
4855
February1st to 10thNight
64%39%16%7%1
2399
11th to 20thNight
58%310%20%8%1
2221
21st to endNight
57%28%18%13%1
1776
March1st to 10thNight
59%39%17%11%2
2160
11th to 20thNight
56%28%19%12%3
2041
21st to endNight
52%25%22%15%5%
2019
April1st to 10thNight
56%27%19%14%2
1800
11th to 20thNight
52%36%22%16%2
1775
21st to endNight
52%27%19%15%4
1702
May1st to 10thNight
51%26%20%17%4
1442
11th to 20thNight
46%36%22%20%4
1416
21st to endNight
42%413%21%17%3
1551
June1st to 10thNight
51%311%22%12%1
1440
11th to 20thNight
43%411%23%18%2
1440
21st to endNight
47%413%21%14%
1440
July1st to 10thNight
36%413%28%18%1
1400
11th to 20thNight
39%412%32%13%
1392
21st to endNight
38%417%27%14%1
1486
August1st to 10thNight
37%419%28%12%
1422
11th to 20thNight
40%316%28%12%1
1620
21st to endNight
40%315%30%11%1
1980
September1st to 10thNight
43%210%28%16%1
1800
11th to 20thNight
37%312%35%12%1
1840
21st to endNight
42%311%31%12%
1980
October1st to 10thNight
48%410%25%13%1
2151
11th to 20thNight
54%311%23%9%
2160
21st to endNight
59%312%17%9%1
2569
November1st to 10thNight
53%213%22%9%1
2407
11th to 20thNight
55%312%20%9%1
2588
21st to endNight
61%213%17%6%
2660
December1st to 10thNight
69%39%15%4
2660
11th to 20thNight
65%28%18%7%1
3288
21st to endNight
72%18%14%4
4884

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
26%20%30%20%4
180
11th to 20thDay
28%27%29%11%41
180
21st to endDay
20%19%38%18%5%
204
February1st to 10thDay
31%31%27%10%1
252
11th to 20thDay
25%26%38%11%
294
21st to endDay
31%19%31%17%2
346
March1st to 10thDay
26%19%32%19%4
420
11th to 20thDay
26%24%30%17%31
420
21st to endDay
32%19%23%17%8%1
462
April1st to 10thDay
30%17%31%16%5%1
420
11th to 20thDay
31%19%23%17%8%2
412
21st to endDay
30%19%26%16%8%1
420
May1st to 10thDay
24%17%33%18%7%2
423
11th to 20thDay
20%17%32%20%10%2
447
21st to endDay
18%18%33%21%9%1
485
June1st to 10thDay
28%11%27%24%8%2
450
11th to 20thDay
16%14%30%26%11%2
450
21st to endDay
23%10%32%20%12%3
450
July1st to 10thDay
14%10%29%29%16%3
445
11th to 20thDay
13%10%32%28%16%3
444
21st to endDay
16%9%30%31%13%2
488
August1st to 10thDay
14%8%26%31%16%4
446
11th to 20thDay
15%8%22%33%16%7%
439
21st to endDay
15%11%26%25%15%7%
495
September1st to 10thDay
16%12%28%21%17%6%
450
11th to 20thDay
14%10%23%24%18%10%
450
21st to endDay
18%13%29%20%16%5%
450
October1st to 10thDay
23%16%25%20%13%3
450
11th to 20thDay
26%20%27%18%8%1
450
21st to endDay
33%12%31%18%6%
399
November1st to 10thDay
28%18%26%19%8%1
365
11th to 20thDay
25%21%31%17%6%
247
21st to endDay
27%22%29%16%6%1
180
December1st to 10thDay
31%17%33%16%3
180
11th to 20thDay
29%24%33%12%11
180
21st to endDay
34%23%28%13%2
198
January1st to 10thNight
27%16%34%17%4
760
11th to 20thNight
28%15%32%20%41
760
21st to endNight
21%14%35%25%5%
836
February1st to 10thNight
22%16%36%22%4
739
11th to 20thNight
21%18%37%20%4
703
21st to endNight
25%15%32%25%3
592
March1st to 10thNight
23%15%35%22%4
720
11th to 20thNight
25%16%33%22%31
720
21st to endNight
24%14%28%27%7%1
792
April1st to 10thNight
30%12%30%24%4
720
11th to 20thNight
25%15%32%22%6%
711
21st to endNight
27%14%28%22%8%
622
May1st to 10thNight
26%9%30%25%8%2
362
11th to 20thNight
21%11%31%27%9%1
354
21st to endNight
17%7%37%30%10%1
389
June1st to 10thNight
21%6%30%35%8%1
360
11th to 20thNight
19%6%27%33%13%1
360
21st to endNight
16%5%31%30%17%1
360
July1st to 10thNight
10%7%28%37%17%1
350
11th to 20thNight
11%428%41%15%
348
21st to endNight
13%5%30%36%14%1
394
August1st to 10thNight
13%323%41%19%1
358
11th to 20thNight
14%421%35%23%2
556
21st to endNight
15%5%27%32%18%2
792
September1st to 10thNight
14%5%28%37%15%1
720
11th to 20thNight
19%7%19%32%19%3
720
21st to endNight
19%8%27%26%18%2
720
October1st to 10thNight
24%8%29%27%12%1
720
11th to 20thNight
25%11%30%24%9%
720
21st to endNight
28%12%31%24%5%
792
November1st to 10thNight
27%13%26%25%8%
740
11th to 20thNight
23%18%32%17%9%1
760
21st to endNight
28%16%29%20%7%
760
December1st to 10thNight
30%15%31%20%5%
760
11th to 20thNight
30%18%28%18%5%1
760
21st to endNight
38%15%28%15%4
836
Page generated at 2024-02-02 05:20:32. Version ac07

Copyright 2024 Attilla Danko


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