Caledonia
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Caledonia clear sky chart from 2005-11-05 to 2017-10-06.

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
38%
16078
17%
47058
10%
16035
44%
16035
24%
31570

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
22%
900
14%
2506
5%
895
29%
895
18%
1856
January16th to endNight
23%
960
11%
2637
4%
960
29%
960
16%
1997
February1st to 15thNight
24%
834
14%
2245
4%
834
31%
834
21%
1624
February16th to endNight
27%
631
18%
1893
8%
631
36%
631
18%
1324
March1st to 15thNight
30%
720
14%
2160
7%
720
35%
720
20%
1480
March16th to endNight
32%
591
15%
2001
11%
591
40%
591
18%
1382
April1st to 15thNight
29%
539
15%
1797
10%
539
38%
539
19%
1225
April16th to endNight
33%
540
19%
1753
11%
540
44%
540
22%
1174
May1st to 15thNight
35%
540
15%
1546
8%
540
41%
540
21%
1099
May16th to endNight
46%
563
17%
1498
9%
561
51%
561
31%
982
June1st to 15thNight
54%
540
15%
1440
10%
540
56%
540
34%
906
June16th to endNight
50%
540
16%
1440
9%
540
54%
540
32%
948
July1st to 15thNight
64%
510
17%
1360
11%
510
66%
510
41%
817
July16th to endNight
69%
564
21%
1417
15%
531
72%
531
41%
833
August1st to 15thNight
76%
539
22%
1560
22%
536
77%
536
42%
865
August16th to endNight
68%
573
20%
1910
21%
573
71%
573
33%
1074
September1st to 15thNight
62%
540
28%
1800
27%
540
68%
540
37%
959
September16th to endNight
56%
699
27%
1962
19%
699
61%
699
35%
1169
October1st to 15thNight
43%
684
23%
2000
17%
684
49%
684
30%
1249
October16th to endNight
32%
704
18%
2222
10%
704
42%
704
22%
1438
November1st to 15thNight
34%
700
23%
2276
17%
700
44%
700
25%
1394
November16th to endNight
26%
807
15%
2427
8%
807
35%
807
18%
1683
December1st to 15thNight
22%
900
12%
2520
4%
900
29%
900
16%
1915
December16th to endNight
18%
960
10%
2688
2%
960
25%
960
12%
2177

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
14%7%36%5%3445%7%36%
48148
Night
14%7%35%424446%40%
47226
Cloud CoverDay
14%8%36%5%3445%7%36%
48156
Night
14%8%35%42445%6%40%
47231
TransparencyDay
46%6%13%21%11%1
47834
Night
44%5%12%22%13%1
47058
SeeingDay
15%6%26%27%17%6%
6086
Night
17%7%30%30%12%1
16081

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
14%12%6%6%5%36%46%7%26%
1432
16th to endDay
14%13%6%12%5%34445%25%
1584
February1st to 15thDay
13%13%5%6%6%36%445%29%
1615
16th to endDay
15%10%38%6%34436%34%
1580
March1st to 15thDay
16%9%36%5%235%47%34%
1790
16th to endDay
19%8%36%6%34446%30%
2232
April1st to 15thDay
18%10%47%6%24446%30%
2151
16th to endDay
21%8%25%5%23446%33%
2205
May1st to 15thDay
20%9%45%5%36%5%5%5%28%
2403
16th to endDay
14%5%35%5%35%5%6%7%38%
2617
June1st to 15thDay
13%5%245%345%6%8%40%
2520
16th to endDay
10%425%435%5%7%10%38%
2520
July1st to 15thDay
8%4245%36%5%7%10%42%
2520
16th to endDay
8%5%25%5%35%6%6%9%41%
2655
August1st to 15thDay
7%424435%5%7%9%44%
2388
16th to endDay
12%5%25%5%35%45%6%44%
2292
September1st to 15thDay
13%313423347%51%
2160
16th to endDay
10%425%5%3435%8%45%
1986
October1st to 15thDay
16%6%25%414345%44%
1757
16th to endDay
19%8%345%3435%5%36%
1650
November1st to 15thDay
13%8%35%4245%46%40%
1582
16th to endDay
17%10%46%5%23236%35%
1533
December1st to 15thDay
19%13%47%6%34335%27%
1440
16th to endDay
20%13%7%8%6%3444422%
1536
January1st to 15thNight
16%11%47%5%23445%33%
2506
16th to endNight
13%10%5%10%6%35%446%28%
2637
February1st to 15thNight
13%13%5%6%434345%36%
2243
16th to endNight
15%12%5%6%423346%34%
1893
March1st to 15thNight
16%9%35%423446%38%
2147
16th to endNight
18%8%34435%447%33%
2001
April1st to 15thNight
19%9%34424445%37%
1797
16th to endNight
19%7%24423345%40%
1753
May1st to 15thNight
18%5%345%35%5%6%7%34%
1546
16th to endNight
10%5%2433447%10%42%
1496
June1st to 15thNight
10%4235%25%45%7%48%
1440
16th to endNight
8%5%345%35%5%5%9%42%
1440
July1st to 15thNight
6%4243245%5%9%52%
1440
16th to endNight
7%312325%5%7%9%50%
1513
August1st to 15thNight
431342445%9%55%
1569
16th to endNight
9%41443345%8%50%
1910
September1st to 15thNight
8%41441335%458%
1800
16th to endNight
10%314434446%52%
1962
October1st to 15thNight
12%6%24433346%48%
2000
16th to endNight
20%6%24323346%41%
2222
November1st to 15thNight
13%6%25%414346%47%
2276
16th to endNight
19%8%36%423445%36%
2427
December1st to 15thNight
20%11%47%434445%29%
2520
16th to endNight
23%13%6%7%5%2434322%
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
13%12%6%6%6%36%5%5%7%26%
1432
16th to endDay
13%13%6%12%6%2444425%
1584
February1st to 15thDay
13%13%5%7%6%35%445%29%
1615
16th to endDay
14%10%37%6%34346%34%
1580
March1st to 15thDay
15%9%46%5%245%47%34%
1800
16th to endDay
18%8%35%6%4445%6%30%
2230
April1st to 15thDay
18%9%47%6%34446%29%
2151
16th to endDay
19%8%36%43345%6%33%
2205
May1st to 15thDay
19%9%46%5%36%5%46%28%
2403
16th to endDay
13%5%25%6%345%6%7%37%
2617
June1st to 15thDay
12%5%25%5%345%5%8%40%
2520
16th to endDay
9%5%25%5%36%5%7%10%38%
2520
July1st to 15thDay
7%4145%35%6%7%11%41%
2520
16th to endDay
7%5%25%5%35%5%6%9%41%
2655
August1st to 15thDay
7%4245%345%8%9%43%
2388
16th to endDay
11%5%245%35%45%7%43%
2292
September1st to 15thDay
12%413423447%50%
2160
16th to endDay
9%5%25%5%3446%7%45%
1986
October1st to 15thDay
16%6%34423346%44%
1757
16th to endDay
19%8%345%34445%36%
1650
November1st to 15thDay
13%8%45%425%5%5%5%40%
1582
16th to endDay
18%11%46%6%23336%35%
1533
December1st to 15thDay
18%13%47%6%34445%27%
1440
16th to endDay
20%13%6%8%6%3444422%
1536
January1st to 15thNight
15%12%47%5%33345%33%
2506
16th to endNight
12%10%5%10%6%35%5%46%28%
2637
February1st to 15thNight
13%13%5%6%5%24345%36%
2236
16th to endNight
15%11%5%6%42335%6%34%
1893
March1st to 15thNight
16%9%35%423346%38%
2160
16th to endNight
17%8%44435%438%33%
2001
April1st to 15thNight
19%9%34425%445%36%
1797
16th to endNight
18%8%34423345%40%
1753
May1st to 15thNight
17%6%34445%5%5%7%34%
1545
16th to endNight
10%5%2443447%9%42%
1496
June1st to 15thNight
10%4145%25%45%7%47%
1440
16th to endNight
8%5%345%35%5%410%42%
1440
July1st to 15thNight
6%3243145%5%9%52%
1440
16th to endNight
6%312325%5%7%9%50%
1513
August1st to 15thNight
431342446%10%54%
1569
16th to endNight
8%41442436%7%51%
1910
September1st to 15thNight
8%41432235%5%58%
1800
16th to endNight
9%41442435%6%51%
1962
October1st to 15thNight
12%6%25%434345%48%
2000
16th to endNight
19%7%24324346%41%
2222
November1st to 15thNight
13%6%25%424246%47%
2276
16th to endNight
18%9%36%5%23445%36%
2427
December1st to 15thNight
20%11%37%5%34445%29%
2520
16th to endNight
22%14%5%8%6%2444422%
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
55%6%14%15%7%
1433
16th to endDay
60%5%12%14%6%
1584
February1st to 15thDay
56%5%11%17%7%
1617
16th to endDay
52%6%10%21%8%
1580
March1st to 15thDay
49%6%14%20%8%
1800
16th to endDay
53%6%13%19%6%
2232
April1st to 15thDay
55%410%20%8%
2151
16th to endDay
50%5%11%18%11%1
2205
May1st to 15thDay
55%7%12%19%5%
2403
16th to endDay
43%8%12%21%13%1
2621
June1st to 15thDay
39%7%13%24%13%
2520
16th to endDay
38%7%15%22%14%1
2520
July1st to 15thDay
34%7%15%25%14%1
2371
16th to endDay
35%7%18%21%13%2
2488
August1st to 15thDay
33%9%14%28%12%1
2373
16th to endDay
37%7%12%24%15%2
2292
September1st to 15thDay
33%5%9%28%20%2
2160
16th to endDay
36%411%29%15%1
1986
October1st to 15thDay
41%411%26%14%
1757
16th to endDay
49%5%12%21%9%1
1650
November1st to 15thDay
44%5%12%23%12%1
1582
16th to endDay
51%315%23%5%
1533
December1st to 15thDay
59%414%15%5%
1440
16th to endDay
65%5%11%10%7%
1536
January1st to 15thNight
53%5%9%19%10%
2506
16th to endNight
55%5%14%14%9%
2637
February1st to 15thNight
51%411%20%11%
2245
16th to endNight
50%5%11%22%8%2
1893
March1st to 15thNight
47%5%14%17%12%1
2160
16th to endNight
49%5%12%21%8%1
2001
April1st to 15thNight
48%5%9%21%14%1
1797
16th to endNight
46%410%22%12%3
1753
May1st to 15thNight
46%8%12%20%11%
1546
16th to endNight
36%8%14%21%16%2
1498
June1st to 15thNight
34%6%13%24%19%1
1440
16th to endNight
36%7%13%19%20%2
1440
July1st to 15thNight
27%7%13%29%20%2
1360
16th to endNight
26%7%16%28%17%3
1417
August1st to 15thNight
24%7%13%32%19%2
1560
16th to endNight
30%6%13%26%18%3
1910
September1st to 15thNight
28%410%25%28%2
1800
16th to endNight
32%5%10%32%17%1
1962
October1st to 15thNight
37%5%10%25%20%1
2000
16th to endNight
44%412%25%11%1
2222
November1st to 15thNight
39%410%23%18%3
2276
16th to endNight
49%413%20%10%
2427
December1st to 15thNight
57%410%18%7%
2520
16th to endNight
65%410%12%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
24%8%33%30%3
90
16th to endDay
22%5%32%30%7%2
96
February1st to 15thDay
18%15%43%16%5%
90
16th to endDay
24%12%30%23%8%
81
March1st to 15thDay
27%15%36%16%3
90
16th to endDay
31%5%27%21%12%1
222
April1st to 15thDay
24%11%29%23%10%1
270
16th to endDay
23%10%27%24%10%4
270
May1st to 15thDay
22%11%29%24%9%2
360
16th to endDay
17%8%31%23%14%4
517
June1st to 15thDay
13%5%29%30%17%4
495
16th to endDay
11%6%31%29%15%5%
495
July1st to 15thDay
9%224%30%22%9%
475
16th to endDay
8%221%33%22%10%
515
August1st to 15thDay
8%217%31%26%13%
439
16th to endDay
13%413%28%28%11%
332
September1st to 15thDay
11%217%30%27%10%
315
16th to endDay
9%422%28%27%7%
314
October1st to 15thDay
12%6%27%27%22%3
158
16th to endDay
22%9%28%34%5%
96
November1st to 15thDay
7%10%31%27%16%6%
90
16th to endDay
35%12%34%8%8%
90
December1st to 15thDay
23%10%37%23%5%
90
16th to endDay
29%15%45%7%2
96
January1st to 15thNight
21%11%37%23%6%
900
16th to endNight
17%11%37%29%4
960
February1st to 15thNight
20%8%39%25%5%
837
16th to endNight
20%10%34%26%6%
631
March1st to 15thNight
20%8%33%28%7%
720
16th to endNight
20%9%31%27%9%
591
April1st to 15thNight
23%11%31%27%5%
539
16th to endNight
22%6%33%26%9%
540
May1st to 15thNight
20%6%32%30%10%
540
16th to endNight
13%331%36%15%
563
June1st to 15thNight
10%426%43%14%
540
16th to endNight
10%330%38%17%
540
July1st to 15thNight
8%20%42%25%2
510
16th to endNight
7%116%47%25%1
564
August1st to 15thNight
6%11%48%30%3
539
16th to endNight
10%113%38%30%4
573
September1st to 15thNight
10%219%34%27%5%
540
16th to endNight
11%421%33%26%2
699
October1st to 15thNight
15%6%29%30%16%1
684
16th to endNight
23%9%31%26%8%
704
November1st to 15thNight
18%9%34%26%11%
700
16th to endNight
22%10%33%26%7%
807
December1st to 15thNight
25%9%37%21%5%
900
16th to endNight
29%9%32%24%3
960
Page generated at 2017-10-07 13:07:54. Version ac04

Copyright 2017 A. Danko


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