Beamsville
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Beamsville 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
37%
15473
14%
48860
10%
15434
42%
15434
18%
34479

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%
777
8%
2661
3%
776
18%
776
6%
2189
January16th to endNight
15%
832
8%
2704
2%
832
22%
832
8%
2174
February1st to 15thNight
14%
759
6%
2468
2%
757
20%
757
8%
1983
February16th to endNight
22%
631
9%
2005
4%
631
30%
631
12%
1538
March1st to 15thNight
25%
720
12%
1980
6%
720
30%
720
15%
1532
March16th to endNight
36%
768
19%
2112
11%
768
43%
768
23%
1478
April1st to 15thNight
33%
718
15%
1821
6%
718
37%
718
22%
1336
April16th to endNight
46%
572
21%
1652
10%
572
53%
572
27%
1077
May1st to 15thNight
49%
507
17%
1587
13%
507
54%
507
25%
1037
May16th to endNight
55%
374
17%
1497
20%
374
61%
374
24%
866
June1st to 15thNight
50%
360
13%
1440
15%
360
57%
360
20%
882
June16th to endNight
58%
360
13%
1440
18%
360
63%
360
24%
834
July1st to 15thNight
68%
340
17%
1360
25%
340
70%
340
33%
685
July16th to endNight
66%
509
15%
1540
16%
476
67%
476
34%
885
August1st to 15thNight
70%
539
16%
1609
14%
536
72%
536
34%
962
August16th to endNight
65%
630
23%
1776
16%
630
68%
630
38%
1034
September1st to 15thNight
59%
720
21%
1812
12%
720
63%
720
34%
1184
September16th to endNight
58%
717
22%
2004
17%
717
61%
717
32%
1268
October1st to 15thNight
44%
720
17%
2160
15%
720
48%
720
22%
1488
October16th to endNight
26%
768
14%
2304
8%
768
34%
768
16%
1687
November1st to 15thNight
36%
760
17%
2556
15%
760
42%
760
19%
1729
November16th to endNight
25%
780
11%
2730
8%
780
32%
780
12%
2010
December1st to 15thNight
16%
780
5%
2730
2%
780
20%
780
8%
2183
December16th to endNight
11%
832
6%
2912
1%
832
16%
832
6%
2438

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
13%8%36%6%35%5%5%7%33%
49217
Night
15%9%47%6%3445%6%33%
49042
Cloud CoverDay
14%8%36%6%35%5%5%7%33%
49227
Night
15%9%37%5%3445%6%33%
49046
TransparencyDay
47%6%14%20%10%
48917
Night
51%5%12%19%10%1
48860
SeeingDay
17%5%22%26%19%8%
5799
Night
20%8%25%28%14%2
15478

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
15%13%5%8%9%47%6%5%6%16%
1604
16th to endDay
13%13%5%14%9%5%6%5%5%6%14%
1872
February1st to 15thDay
16%17%5%10%7%35%5%6%5%16%
1695
16th to endDay
15%14%410%8%35%5%5%7%18%
1467
March1st to 15thDay
15%9%5%10%8%345%5%5%24%
1969
16th to endDay
14%8%36%5%35%5%47%35%
2112
April1st to 15thDay
18%8%35%6%345%46%32%
2126
16th to endDay
15%6%35%5%34446%40%
2319
May1st to 15thDay
13%6%26%6%35%6%6%7%37%
2364
16th to endDay
9%5%25%426%6%5%8%42%
2618
June1st to 15thDay
12%5%25%5%35%46%8%40%
2520
16th to endDay
11%3145%35%5%7%10%41%
2520
July1st to 15thDay
6%4145%36%5%7%9%45%
2520
16th to endDay
9%325%5%36%6%7%9%39%
2519
August1st to 15thDay
6%425%5%45%6%8%11%40%
2340
16th to endDay
9%4145%345%5%8%46%
2414
September1st to 15thDay
13%5%15%5%345%5%7%41%
2146
16th to endDay
12%425%6%3445%7%42%
1956
October1st to 15thDay
18%7%26%5%35%45%6%34%
1800
16th to endDay
21%10%37%6%35%445%26%
1920
November1st to 15thDay
12%8%47%6%35%45%8%33%
1632
16th to endDay
17%12%37%6%345%5%7%25%
1560
December1st to 15thDay
15%13%6%10%7%45%45%6%21%
1560
16th to endDay
19%14%7%10%8%45%5%5%5%12%
1664
January1st to 15thNight
18%15%5%9%8%45%34419%
2661
16th to endNight
14%13%6%10%8%45%5%6%6%18%
2704
February1st to 15thNight
15%14%6%10%7%35%5%46%21%
2466
16th to endNight
15%11%5%9%8%35%45%8%22%
2005
March1st to 15thNight
19%11%47%8%35%446%25%
1968
16th to endNight
14%8%46%5%24435%38%
2112
April1st to 15thNight
18%9%35%5%34446%33%
1821
16th to endNight
11%7%35%435%446%42%
1652
May1st to 15thNight
15%6%36%43345%8%38%
1587
16th to endNight
11%5%345%2445%6%46%
1495
June1st to 15thNight
11%5%36%5%35%5%6%9%38%
1440
16th to endNight
8%425%5%45%5%5%8%43%
1440
July1st to 15thNight
5%315%4245%5%8%53%
1440
16th to endNight
7%315%4245%7%8%48%
1647
August1st to 15thNight
7%2145%35%6%7%8%47%
1620
16th to endNight
7%425%42446%6%51%
1776
September1st to 15thNight
13%5%2443345%7%45%
1812
16th to endNight
12%425%5%33447%46%
2004
October1st to 15thNight
18%6%36%5%24346%37%
2160
16th to endNight
23%8%36%5%3445%7%28%
2304
November1st to 15thNight
16%7%35%6%35%447%36%
2556
16th to endNight
19%9%46%5%35%5%5%6%27%
2730
December1st to 15thNight
18%16%5%8%6%35%45%5%20%
2730
16th to endNight
19%14%7%10%8%4445%5%14%
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%14%5%9%8%46%6%5%5%17%
1604
16th to endDay
12%13%6%13%10%5%6%5%45%15%
1872
February1st to 15thDay
17%16%5%10%7%35%6%5%417%
1695
16th to endDay
16%14%5%10%8%35%45%7%18%
1467
March1st to 15thDay
15%11%5%9%8%35%5%45%25%
1980
16th to endDay
14%9%36%5%35%446%35%
2111
April1st to 15thDay
19%9%35%6%3445%5%31%
2126
16th to endDay
16%6%346%34445%40%
2319
May1st to 15thDay
14%5%36%5%45%45%7%36%
2364
16th to endDay
10%5%25%435%5%6%8%42%
2618
June1st to 15thDay
13%5%25%5%3445%8%39%
2520
16th to endDay
11%325%5%35%5%7%10%41%
2520
July1st to 15thDay
7%5%24435%5%7%9%44%
2520
16th to endDay
9%326%5%45%6%7%9%38%
2519
August1st to 15thDay
7%425%445%6%8%10%40%
2340
16th to endDay
10%425%5%3445%7%46%
2414
September1st to 15thDay
13%5%246%35%46%7%40%
2146
16th to endDay
13%5%25%6%35%45%6%41%
1956
October1st to 15thDay
18%8%26%5%35%446%35%
1800
16th to endDay
23%10%37%6%44445%26%
1920
November1st to 15thDay
12%8%37%6%35%45%7%34%
1632
16th to endDay
17%12%36%6%35%5%6%6%26%
1560
December1st to 15thDay
16%14%5%9%7%3445%6%21%
1560
16th to endDay
20%15%7%9%8%45%5%46%12%
1664
January1st to 15thNight
19%15%5%9%8%35%44419%
2661
16th to endNight
14%13%5%11%7%45%5%5%6%19%
2704
February1st to 15thNight
15%14%5%10%6%35%445%21%
2459
16th to endNight
15%12%6%9%7%35%45%6%23%
2005
March1st to 15thNight
20%11%38%7%34446%25%
1980
16th to endNight
15%9%37%424445%38%
2112
April1st to 15thNight
19%9%36%6%24445%34%
1821
16th to endNight
12%6%25%435%45%6%42%
1652
May1st to 15thNight
16%6%35%5%2345%8%37%
1586
16th to endNight
11%5%25%5%335%5%6%45%
1495
June1st to 15thNight
12%5%35%5%45%46%8%38%
1440
16th to endNight
9%425%6%35%5%5%8%43%
1440
July1st to 15thNight
6%31442445%8%54%
1440
16th to endNight
8%3144245%6%9%48%
1647
August1st to 15thNight
6%414436%6%6%9%46%
1620
16th to endNight
7%325%42446%6%51%
1776
September1st to 15thNight
14%5%24424446%46%
1812
16th to endNight
12%5%25%433347%47%
2004
October1st to 15thNight
18%7%26%5%23346%39%
2160
16th to endNight
23%7%36%5%345%5%7%28%
2304
November1st to 15thNight
16%7%35%5%245%46%36%
2556
16th to endNight
18%10%45%6%35%5%5%6%27%
2730
December1st to 15thNight
19%16%5%7%5%25%5%5%5%20%
2730
16th to endNight
19%14%7%10%8%35%5%45%15%
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
69%5%11%11%2
1605
16th to endDay
70%6%11%9%2
1872
February1st to 15thDay
69%5%11%11%2
1697
16th to endDay
65%413%13%3
1467
March1st to 15thDay
59%5%13%15%5%
1980
16th to endDay
48%312%23%10%1
2112
April1st to 15thDay
50%5%13%18%11%
2126
16th to endDay
43%5%11%21%15%2
2319
May1st to 15thDay
43%6%12%24%12%
2364
16th to endDay
36%6%15%25%14%1
2622
June1st to 15thDay
40%5%15%25%12%1
2520
16th to endDay
35%6%16%25%14%
2520
July1st to 15thDay
30%7%14%26%20%1
2371
16th to endDay
37%7%16%24%12%1
2363
August1st to 15thDay
33%6%19%24%14%1
2327
16th to endDay
33%6%14%30%13%1
2414
September1st to 15thDay
39%6%15%25%12%
2146
16th to endDay
40%416%26%11%
1956
October1st to 15thDay
48%5%11%21%11%
1800
16th to endDay
59%5%15%14%4
1920
November1st to 15thDay
47%6%17%19%8%
1632
16th to endDay
56%6%15%16%5%
1560
December1st to 15thDay
63%6%16%11%1
1560
16th to endDay
72%6%8%10%1
1664
January1st to 15thNight
70%410%11%3
2661
16th to endNight
66%5%11%12%3
2704
February1st to 15thNight
67%412%12%3
2468
16th to endNight
61%413%15%5%
2005
March1st to 15thNight
59%412%17%4
1980
16th to endNight
47%48%23%13%1
2112
April1st to 15thNight
51%49%19%13%
1821
16th to endNight
42%410%22%17%3
1652
May1st to 15thNight
44%411%24%12%2
1587
16th to endNight
37%5%13%25%15%2
1497
June1st to 15thNight
41%7%10%22%16%1
1440
16th to endNight
37%6%14%24%16%1
1440
July1st to 15thNight
27%5%12%26%25%2
1360
16th to endNight
31%5%16%24%17%3
1540
August1st to 15thNight
31%7%17%27%13%1
1609
16th to endNight
30%5%13%32%16%1
1776
September1st to 15thNight
37%413%27%15%1
1812
16th to endNight
38%412%28%15%
2004
October1st to 15thNight
48%49%22%14%
2160
16th to endNight
55%414%18%6%
2304
November1st to 15thNight
47%6%12%22%11%
2556
16th to endNight
56%6%14%18%4
2730
December1st to 15thNight
65%6%14%10%3
2730
16th to endNight
71%5%10%9%2
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
15%15%38%16%12%
102
16th to endDay
26%12%37%19%4
144
February1st to 15thDay
26%10%43%19%
130
16th to endDay
19%9%37%25%8%
96
March1st to 15thDay
22%10%29%27%8%
270
16th to endDay
21%6%28%30%8%3
288
April1st to 15thDay
22%430%29%10%2
270
16th to endDay
20%425%28%15%5%
270
May1st to 15thDay
21%221%26%22%6%
288
16th to endDay
13%219%33%22%9%
331
June1st to 15thDay
14%318%36%21%5%
315
16th to endDay
16%118%31%26%6%
315
July1st to 15thDay
11%112%32%28%13%
305
16th to endDay
10%114%34%24%14%
326
August1st to 15thDay
11%12%26%32%17%
313
16th to endDay
12%114%20%29%20%
332
September1st to 15thDay
12%116%21%32%15%
315
16th to endDay
15%215%21%24%20%
314
October1st to 15thDay
20%6%23%22%19%8%
315
16th to endDay
30%11%23%21%11%
336
November1st to 15thDay
16%12%26%29%11%3
148
16th to endDay
20%15%32%20%12%
90
December1st to 15thDay
14%22%34%18%10%
90
16th to endDay
30%18%39%10%1
96
January1st to 15thNight
28%16%31%17%4
780
16th to endNight
21%14%37%20%5%
832
February1st to 15thNight
24%15%35%20%3
760
16th to endNight
22%11%32%28%5%
631
March1st to 15thNight
26%9%31%24%8%
720
16th to endNight
19%5%30%29%12%2
768
April1st to 15thNight
23%6%28%31%8%
718
16th to endNight
16%327%34%15%2
572
May1st to 15thNight
18%219%33%22%3
507
16th to endNight
12%321%37%22%3
375
June1st to 15thNight
15%122%37%21%1
360
16th to endNight
10%120%44%23%1
360
July1st to 15thNight
6%114%47%26%4
340
16th to endNight
9%113%42%28%4
509
August1st to 15thNight
9%111%38%33%6%
539
16th to endNight
10%113%34%34%5%
630
September1st to 15thNight
15%313%32%27%7%
720
16th to endNight
14%215%27%28%10%
717
October1st to 15thNight
22%6%19%26%21%3
720
16th to endNight
29%9%28%25%6%
768
November1st to 15thNight
20%8%28%25%15%1
760
16th to endNight
27%13%27%21%8%1
780
December1st to 15thNight
32%14%30%18%4
780
16th to endNight
27%13%36%18%4
832
Page generated at 2018-02-15 10:58:38. Version ac04

Copyright 2018 A. Danko


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