Sandbanks Provincial Park
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Sandbanks Provincial Park clear sky chart from 2005-11-05 to 2019-06-24.

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
24%
17563
8%
54028
4%
17516
28%
17516
11%
42886

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
12%
898
5%
2926
1%
896
17%
896
4%
2549
January16th to endNight
13%
960
5%
3136
2%
960
17%
960
7%
2624
February1st to 15thNight
14%
857
5%
2784
1%
854
18%
854
6%
2350
February16th to endNight
19%
735
6%
2205
3%
735
23%
735
10%
1772
March1st to 15thNight
19%
840
11%
2508
4%
836
25%
836
13%
1937
March16th to endNight
21%
714
10%
2346
5%
714
29%
714
12%
1806
April1st to 15thNight
24%
629
10%
2096
7%
629
31%
629
11%
1596
April16th to endNight
28%
623
12%
1900
7%
623
35%
623
15%
1454
May1st to 15thNight
34%
630
11%
1698
5%
630
38%
630
19%
1283
May16th to endNight
29%
657
8%
1752
3%
656
31%
656
15%
1390
June1st to 15thNight
28%
630
5%
1502
2%
630
30%
630
14%
1243
June16th to endNight
33%
610
4%
1440
3%
610
34%
610
15%
1199
July1st to 15thNight
38%
555
5%
1480
4%
555
39%
555
14%
1200
July16th to endNight
30%
613
7%
1547
3%
580
32%
580
12%
1268
August1st to 15thNight
42%
574
9%
1535
5%
570
44%
570
17%
1204
August16th to endNight
41%
621
11%
1979
9%
621
44%
621
16%
1461
September1st to 15thNight
36%
585
12%
1963
10%
585
42%
585
15%
1395
September16th to endNight
33%
583
15%
2145
10%
583
41%
583
18%
1420
October1st to 15thNight
31%
713
13%
2282
6%
713
38%
713
17%
1645
October16th to endNight
20%
896
8%
2704
3%
896
24%
896
13%
2131
November1st to 15thNight
22%
880
9%
2671
4%
880
27%
880
10%
2175
November16th to endNight
16%
900
7%
3003
2%
900
21%
900
8%
2426
December1st to 15thNight
15%
900
6%
3150
2%
900
20%
900
6%
2620
December16th to endNight
15%
960
6%
3276
3%
960
19%
960
6%
2738

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
27%10%36%5%24446%23%
54775
Night
26%11%46%5%34445%24%
54212
TransparencyDay
61%6%12%13%5%
54464
Night
63%5%11%13%5%
54041
SeeingDay
34%8%22%22%9%1
10374
Night
32%9%25%22%8%
17565

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%12%8%11%8%45%435%14%
1672
16th to endDay
18%16%6%10%8%47%5%4412%
1792
February1st to 15thDay
18%12%5%11%9%46%6%5%5%14%
1733
16th to endDay
18%13%6%10%8%34435%20%
1840
March1st to 15thDay
19%10%5%9%8%34436%24%
2090
16th to endDay
20%14%46%7%34345%25%
2579
April1st to 15thDay
24%13%5%9%6%23345%22%
2513
16th to endDay
30%10%3432333428%
2664
May1st to 15thDay
28%8%35%323346%29%
2912
16th to endDay
28%9%35%42445%7%24%
3066
June1st to 15thDay
32%8%36%424447%22%
3114
16th to endDay
38%8%25%423335%20%
3024
July1st to 15thDay
30%8%25%424346%25%
2730
16th to endDay
41%6%2442333422%
2877
August1st to 15thDay
29%6%25%6%24448%25%
2665
16th to endDay
28%6%25%4245%46%28%
2574
September1st to 15thDay
27%7%24434347%29%
2327
16th to endDay
24%5%25%4245%5%7%31%
2145
October1st to 15thDay
24%7%245%2445%7%31%
2007
16th to endDay
31%10%45%423446%22%
1872
November1st to 15thDay
29%13%38%423345%20%
1847
16th to endDay
25%13%47%5%24346%20%
1613
December1st to 15thDay
28%14%36%5%35%445%17%
1470
16th to endDay
22%14%5%8%5%4445%419%
1649
January1st to 15thNight
22%14%8%9%7%345%5%5%14%
2926
16th to endNight
21%13%6%8%8%35%5%5%5%16%
3136
February1st to 15thNight
21%12%5%10%8%35%35%6%17%
2784
16th to endNight
16%14%5%9%7%345%45%23%
2205
March1st to 15thNight
19%11%5%7%6%34335%28%
2507
16th to endNight
21%13%47%43444426%
2346
April1st to 15thNight
27%12%46%433335%25%
2096
16th to endNight
26%10%46%5%24335%28%
1900
May1st to 15thNight
28%9%34422335%31%
1698
16th to endNight
32%9%35%5%23335%25%
1750
June1st to 15thNight
33%11%35%5%24235%22%
1502
16th to endNight
36%11%35%42233423%
1440
July1st to 15thNight
34%10%35%43333422%
1560
16th to endNight
42%8%3431323422%
1643
August1st to 15thNight
29%8%145%2445%6%26%
1546
16th to endNight
27%7%25%424446%30%
1979
September1st to 15thNight
29%6%24423435%33%
1963
16th to endNight
24%5%25%41345%6%36%
2145
October1st to 15thNight
24%6%25%424445%34%
2282
16th to endNight
28%10%35%5%2344425%
2704
November1st to 15thNight
29%11%36%5%34345%22%
2671
16th to endNight
29%12%36%424445%21%
3003
December1st to 15thNight
28%12%5%6%5%33345%19%
3150
16th to endNight
23%13%6%7%6%35%445%18%
3276

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
75%5%9%8%1
1673
16th to endDay
74%5%10%6%2
1792
February1st to 15thDay
72%6%12%7%2
1736
16th to endDay
66%411%13%4
1840
March1st to 15thDay
61%6%11%13%6%
2100
16th to endDay
59%6%11%13%8%1
2579
April1st to 15thDay
63%5%7%13%7%1
2513
16th to endDay
59%5%9%14%9%1
2664
May1st to 15thDay
55%5%12%19%7%
2912
16th to endDay
58%5%12%16%5%
3070
June1st to 15thDay
62%6%10%13%5%
3114
16th to endDay
67%5%10%12%4
3024
July1st to 15thDay
60%413%16%5%
2582
16th to endDay
66%6%9%12%5%
2710
August1st to 15thDay
57%8%16%13%3
2651
16th to endDay
53%7%18%16%4
2574
September1st to 15thDay
53%6%13%18%7%
2327
16th to endDay
48%7%17%20%6%
2145
October1st to 15thDay
50%8%15%17%8%
2007
16th to endDay
62%6%11%16%4
1872
November1st to 15thDay
65%6%11%12%3
1847
16th to endDay
66%6%13%9%4
1613
December1st to 15thDay
68%7%11%9%3
1470
16th to endDay
67%7%11%9%3
1649
January1st to 15thNight
74%6%9%7%2
2926
16th to endNight
70%5%13%7%2
3136
February1st to 15thNight
72%5%12%8%1
2785
16th to endNight
64%6%12%12%4
2205
March1st to 15thNight
60%412%15%6%
2520
16th to endNight
61%5%10%15%6%
2346
April1st to 15thNight
60%5%10%13%8%
2096
16th to endNight
60%48%15%10%1
1900
May1st to 15thNight
56%411%19%7%
1698
16th to endNight
62%48%16%7%
1752
June1st to 15thNight
66%38%13%6%
1502
16th to endNight
65%5%7%14%7%
1440
July1st to 15thNight
63%5%10%12%8%
1480
16th to endNight
66%5%8%13%6%
1547
August1st to 15thNight
56%8%12%16%5%
1535
16th to endNight
54%6%12%20%5%
1979
September1st to 15thNight
53%5%12%19%9%
1963
16th to endNight
46%6%15%20%9%
2145
October1st to 15thNight
50%8%14%18%7%
2282
16th to endNight
61%5%12%14%5%
2704
November1st to 15thNight
64%7%11%13%2
2671
16th to endNight
67%5%13%9%4
3003
December1st to 15thNight
68%7%12%9%2
3150
16th to endNight
69%6%11%9%2
3276

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
29%16%35%15%2
330
16th to endDay
28%15%35%16%2
352
February1st to 15thDay
25%19%33%19%1
326
16th to endDay
28%15%28%18%6%2
290
March1st to 15thDay
25%14%32%20%5%1
330
16th to endDay
30%14%23%19%7%3
397
April1st to 15thDay
34%14%25%17%6%1
390
16th to endDay
35%6%23%22%8%2
554
May1st to 15thDay
35%121%27%10%3
618
16th to endDay
33%5%23%23%12%2
679
June1st to 15thDay
37%317%27%11%1
645
16th to endDay
45%413%25%9%1
610
July1st to 15thDay
39%313%27%14%1
550
16th to endDay
50%211%20%13%1
594
August1st to 15thDay
34%114%28%19%1
550
16th to endDay
33%215%27%17%3
486
September1st to 15thDay
29%5%22%30%10%2
371
16th to endDay
27%5%26%29%9%1
314
October1st to 15thDay
26%9%31%19%12%1
315
16th to endDay
41%10%25%12%8%1
336
November1st to 15thDay
34%16%25%16%6%1
325
16th to endDay
36%14%23%17%7%
330
December1st to 15thDay
34%16%31%11%5%
330
16th to endDay
32%19%24%15%5%1
352
January1st to 15thNight
30%18%29%18%3
900
16th to endNight
27%16%34%17%3
960
February1st to 15thNight
28%16%33%16%4
857
16th to endNight
23%13%33%22%5%1
735
March1st to 15thNight
26%12%33%21%6%
840
16th to endNight
27%10%32%19%8%1
714
April1st to 15thNight
33%10%23%24%7%
629
16th to endNight
32%6%23%29%7%1
623
May1st to 15thNight
31%322%27%12%2
630
16th to endNight
37%221%26%10%1
657
June1st to 15thNight
38%416%29%10%
630
16th to endNight
39%314%25%14%1
610
July1st to 15thNight
40%112%29%14%1
555
16th to endNight
45%213%20%16%
613
August1st to 15thNight
34%111%27%22%1
574
16th to endNight
30%213%29%21%2
621
September1st to 15thNight
32%419%29%11%1
585
16th to endNight
27%5%27%27%11%
583
October1st to 15thNight
28%6%27%27%8%1
713
16th to endNight
32%10%29%21%5%
896
November1st to 15thNight
35%12%24%19%7%
880
16th to endNight
37%13%27%16%5%
900
December1st to 15thNight
34%15%29%14%6%
900
16th to endNight
31%16%28%17%5%
960
Page generated at 2019-06-24 22:41:29. Version ac04

Copyright 2019 A. Danko


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