Haliburton Forest Observatory
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Haliburton Forest Observatory 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%
14554
12%
46286
7%
14521
33%
14521
15%
33656

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
10%
720
6%
2506
2%
716
15%
716
5%
2089
January16th to endNight
17%
768
11%
2541
5%
768
24%
768
10%
2029
February1st to 15thNight
12%
703
9%
2287
3%
701
20%
701
8%
1824
February16th to endNight
17%
631
12%
2027
4%
631
26%
631
11%
1548
March1st to 15thNight
16%
720
13%
2001
5%
720
24%
720
14%
1530
March16th to endNight
29%
768
20%
2106
10%
768
37%
768
23%
1434
April1st to 15thNight
20%
718
14%
1796
5%
718
25%
718
18%
1360
April16th to endNight
29%
576
18%
1656
9%
576
35%
576
21%
1150
May1st to 15thNight
35%
420
17%
1500
13%
420
44%
420
20%
974
May16th to endNight
38%
375
13%
1497
9%
374
50%
374
21%
880
June1st to 15thNight
34%
360
9%
1440
6%
360
42%
360
16%
927
June16th to endNight
46%
360
10%
1272
11%
360
51%
360
21%
823
July1st to 15thNight
48%
340
15%
1281
17%
340
54%
340
27%
720
July16th to endNight
48%
398
15%
1439
15%
375
54%
375
24%
849
August1st to 15thNight
54%
527
16%
1575
12%
524
58%
524
31%
961
August16th to endNight
50%
581
16%
1631
7%
581
55%
581
33%
1011
September1st to 15thNight
42%
660
15%
1650
7%
660
46%
660
30%
1122
September16th to endNight
43%
657
19%
1831
13%
657
47%
657
27%
1206
October1st to 15thNight
30%
660
17%
1980
11%
660
38%
660
19%
1399
October16th to endNight
17%
704
9%
2120
4%
704
24%
704
11%
1682
November1st to 15thNight
26%
700
15%
2422
12%
700
32%
700
14%
1720
November16th to endNight
18%
720
10%
2520
5%
720
24%
720
9%
2000
December1st to 15thNight
10%
720
5%
2520
2%
720
14%
720
5%
2154
December16th to endNight
10%
768
7%
2688
2%
768
16%
768
5%
2264

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
19%11%47%5%34446%28%
47689
Night
17%12%5%7%5%34445%29%
46456
Cloud CoverDay
18%11%47%5%34446%28%
47699
Night
17%12%5%7%5%34445%30%
46461
TransparencyDay
56%410%18%9%1
47378
Night
55%410%18%9%
46286
SeeingDay
25%12%29%20%8%3
5433
Night
24%13%29%23%9%1
14555

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
21%17%8%9%5%2424417%
1432
16th to endDay
14%16%7%12%8%4443418%
1680
February1st to 15thDay
12%17%7%14%9%44335%18%
1575
16th to endDay
15%19%6%10%6%3433421%
1446
March1st to 15thDay
16%13%5%9%8%44445%24%
1948
16th to endDay
13%10%5%6%7%3434436%
2118
April1st to 15thDay
23%12%45%5%23345%30%
2152
16th to endDay
20%10%35%323245%37%
2315
May1st to 15thDay
19%9%46%5%35%346%31%
2450
16th to endDay
17%7%25%5%35%45%7%35%
2618
June1st to 15thDay
22%7%36%5%3446%7%27%
2520
16th to endDay
17%6%35%5%36%46%8%31%
2682
July1st to 15thDay
17%6%25%5%345%6%8%35%
2598
16th to endDay
13%6%36%6%45%5%5%9%32%
2630
August1st to 15thDay
15%7%27%6%36%5%5%5%32%
2288
16th to endDay
14%6%25%5%35%5%5%8%35%
2207
September1st to 15thDay
22%7%35%5%23446%33%
1980
16th to endDay
19%6%34423346%39%
1796
October1st to 15thDay
27%8%26%5%24346%28%
1650
16th to endDay
35%12%46%423335%19%
1752
November1st to 15thDay
21%14%36%5%24445%27%
1436
16th to endDay
24%19%7%7%5%2333416%
1440
December1st to 15thDay
20%23%8%10%6%2334412%
1440
16th to endDay
20%22%8%11%5%2324414%
1536
January1st to 15thNight
19%19%8%12%7%3234414%
2506
16th to endNight
13%18%8%10%8%35%445%19%
2541
February1st to 15thNight
12%16%8%12%9%44445%18%
2285
16th to endNight
15%16%6%10%6%34346%22%
2027
March1st to 15thNight
17%12%6%8%7%3432430%
1989
16th to endNight
13%9%45%5%23445%39%
2106
April1st to 15thNight
21%13%45%42323431%
1796
16th to endNight
18%9%35%6%23445%36%
1656
May1st to 15thNight
20%7%25%43446%6%34%
1500
16th to endNight
12%6%24435%5%5%8%40%
1495
June1st to 15thNight
17%7%44425%45%7%35%
1440
16th to endNight
14%7%26%5%3446%7%36%
1272
July1st to 15thNight
10%4145%335%5%5%48%
1359
16th to endNight
11%4245%245%5%9%43%
1536
August1st to 15thNight
11%4244245%5%8%46%
1586
16th to endNight
10%425%4335%5%9%45%
1631
September1st to 15thNight
15%6%35%42346%7%40%
1650
16th to endNight
18%6%14423335%45%
1831
October1st to 15thNight
21%7%35%5%24346%34%
1980
16th to endNight
28%13%46%5%24245%22%
2120
November1st to 15thNight
20%11%45%434446%30%
2422
16th to endNight
24%15%5%7%5%3443421%
2520
December1st to 15thNight
20%23%8%9%7%2333412%
2520
16th to endNight
21%19%9%11%6%2333414%
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
21%18%7%10%6%2324418%
1432
16th to endDay
14%16%7%12%8%4433418%
1680
February1st to 15thDay
12%17%7%14%9%3433418%
1575
16th to endDay
15%19%6%11%6%3432421%
1446
March1st to 15thDay
16%13%5%9%8%34445%25%
1959
16th to endDay
12%10%6%5%7%3434436%
2117
April1st to 15thDay
22%13%45%423335%30%
2152
16th to endDay
20%10%35%423236%37%
2315
May1st to 15thDay
18%9%37%5%35%446%31%
2450
16th to endDay
17%6%35%5%35%45%7%35%
2618
June1st to 15thDay
22%8%36%5%3445%7%28%
2520
16th to endDay
17%6%26%5%35%5%6%7%31%
2682
July1st to 15thDay
16%6%25%43447%8%35%
2598
16th to endDay
13%6%36%6%45%5%5%8%32%
2630
August1st to 15thDay
15%7%37%7%36%5%6%6%32%
2288
16th to endDay
14%6%25%6%36%5%6%8%35%
2207
September1st to 15thDay
22%6%35%423446%34%
1980
16th to endDay
19%7%25%5%14346%39%
1796
October1st to 15thDay
26%7%36%5%24446%28%
1650
16th to endDay
34%13%36%423335%18%
1752
November1st to 15thDay
20%14%46%5%24445%27%
1436
16th to endDay
23%19%7%8%43433416%
1440
December1st to 15thDay
20%23%8%11%5%2433312%
1440
16th to endDay
20%22%9%10%423335%14%
1536
January1st to 15thNight
19%18%8%11%7%3234414%
2506
16th to endNight
13%17%8%9%8%34435%19%
2541
February1st to 15thNight
12%16%8%12%8%45%445%18%
2278
16th to endNight
15%15%6%10%6%34345%22%
2027
March1st to 15thNight
17%12%48%7%3433329%
2001
16th to endNight
13%9%5%6%42345%5%39%
2106
April1st to 15thNight
22%13%5%45%2323431%
1796
16th to endNight
18%9%25%6%34345%36%
1656
May1st to 15thNight
19%7%344245%6%6%35%
1500
16th to endNight
12%5%34435%46%8%41%
1495
June1st to 15thNight
17%8%25%5%245%5%6%35%
1440
16th to endNight
14%6%35%6%2447%7%36%
1272
July1st to 15thNight
10%5%144345%46%48%
1359
16th to endNight
11%5%25%4345%5%9%43%
1536
August1st to 15thNight
10%425%4235%5%8%45%
1586
16th to endNight
10%425%42445%8%47%
1631
September1st to 15thNight
15%5%25%42345%8%40%
1650
16th to endNight
18%6%2442333445%
1831
October1st to 15thNight
21%8%35%5%33446%34%
1980
16th to endNight
28%13%47%5%2334422%
2120
November1st to 15thNight
20%10%45%43345%5%30%
2422
16th to endNight
24%15%5%7%5%3443421%
2520
December1st to 15thNight
20%23%8%10%7%2333313%
2520
16th to endNight
21%19%9%11%5%3233414%
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
70%39%10%6%
1433
16th to endDay
68%36%11%7%2
1680
February1st to 15thDay
70%28%11%5%
1577
16th to endDay
67%37%11%10%
1446
March1st to 15thDay
61%312%15%6%1
1959
16th to endDay
50%38%18%14%4
2118
April1st to 15thDay
56%37%18%11%1
2152
16th to endDay
50%26%23%13%2
2315
May1st to 15thDay
53%39%19%12%1
2450
16th to endDay
46%5%12%20%13%1
2622
June1st to 15thDay
54%410%21%9%
2520
16th to endDay
48%5%13%20%10%
2682
July1st to 15thDay
42%6%11%28%11%1
2447
16th to endDay
47%5%12%24%9%
2465
August1st to 15thDay
50%5%14%19%9%
2275
16th to endDay
45%5%14%25%8%
2207
September1st to 15thDay
50%413%22%9%
1980
16th to endDay
46%411%28%8%
1796
October1st to 15thDay
57%310%18%9%
1650
16th to endDay
68%410%11%5%
1752
November1st to 15thDay
58%412%16%7%
1436
16th to endDay
71%28%11%31
1440
December1st to 15thDay
76%38%8%2
1440
16th to endDay
74%27%10%5%
1536
January1st to 15thNight
74%37%9%4
2506
16th to endNight
66%36%12%8%
2541
February1st to 15thNight
68%39%12%5%
2287
16th to endNight
63%28%17%8%
2027
March1st to 15thNight
60%310%16%8%
2001
16th to endNight
45%49%21%16%2
2106
April1st to 15thNight
56%35%20%12%1
1796
16th to endNight
49%37%20%16%1
1656
May1st to 15thNight
47%311%19%15%2
1500
16th to endNight
39%5%15%23%14%1
1497
June1st to 15thNight
47%413%19%13%
1440
16th to endNight
44%5%13%24%10%
1272
July1st to 15thNight
33%6%10%29%18%
1281
16th to endNight
37%6%14%28%12%
1439
August1st to 15thNight
34%6%18%28%11%
1575
16th to endNight
34%6%17%30%10%1
1631
September1st to 15thNight
40%6%17%26%9%
1650
16th to endNight
42%412%31%9%
1831
October1st to 15thNight
50%5%10%21%11%
1980
16th to endNight
64%410%14%5%
2120
November1st to 15thNight
54%414%18%7%
2422
16th to endNight
67%49%13%4
2520
December1st to 15thNight
76%37%9%2
2520
16th to endNight
74%37%8%5%
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
35%25%30%10%
60
16th to endDay
32%12%37%13%3
88
February1st to 15thDay
33%23%34%8%
90
16th to endDay
39%12%34%13%
105
March1st to 15thDay
25%18%31%20%3
270
16th to endDay
21%16%32%17%10%1
288
April1st to 15thDay
25%17%31%17%7%
270
16th to endDay
26%18%25%15%10%3
270
May1st to 15thDay
31%8%27%19%6%5%
288
16th to endDay
22%14%30%20%8%2
331
June1st to 15thDay
28%11%30%21%6%1
315
16th to endDay
20%13%33%22%7%2
477
July1st to 15thDay
19%6%32%26%12%2
381
16th to endDay
14%11%32%25%12%3
326
August1st to 15thDay
17%428%26%14%7%
297
16th to endDay
20%6%20%30%13%8%
268
September1st to 15thDay
25%6%25%19%16%7%
255
16th to endDay
21%9%26%24%12%6%
254
October1st to 15thDay
30%14%24%18%7%3
255
16th to endDay
42%12%27%14%2
271
November1st to 15thDay
22%18%33%20%5%
90
16th to endDay
43%11%30%13%1
60
December1st to 15thDay
30%26%28%13%1
60
16th to endDay
34%42%18%31
64
January1st to 15thNight
30%19%32%14%3
720
16th to endNight
23%15%34%18%7%1
768
February1st to 15thNight
20%20%35%18%4
704
16th to endNight
23%19%33%18%4
631
March1st to 15thNight
25%18%33%19%3
720
16th to endNight
18%13%33%22%10%1
768
April1st to 15thNight
28%16%29%19%6%
718
16th to endNight
24%11%30%21%11%
576
May1st to 15thNight
24%5%29%27%12%1
420
16th to endNight
15%9%33%30%10%
375
June1st to 15thNight
22%9%28%30%8%
360
16th to endNight
16%6%23%44%8%
360
July1st to 15thNight
10%429%36%18%1
340
16th to endNight
12%6%26%37%18%
398
August1st to 15thNight
13%420%36%21%3
527
16th to endNight
12%5%26%32%20%1
581
September1st to 15thNight
18%6%27%28%15%3
660
16th to endNight
23%6%22%28%16%2
657
October1st to 15thNight
25%10%28%23%10%
660
16th to endNight
37%14%25%16%5%
704
November1st to 15thNight
25%15%28%20%9%
700
16th to endNight
35%13%27%17%5%
720
December1st to 15thNight
33%20%29%13%3
720
16th to endNight
32%17%32%14%21
768
Page generated at 2017-08-13 14:16:32. Version ac04

Copyright 2017 A. Danko


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