Hopewell Rocks Provincial Park
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Hopewell Rocks Provincial Park 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
19%
14805
13%
46337
4%
14760
28%
14760
13%
33323

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%
750
12%
2668
1%
746
24%
746
8%
1899
January16th to endNight
13%
773
17%
2524
3%
773
30%
773
12%
1719
February1st to 15thNight
12%
704
10%
2286
2%
701
23%
701
10%
1643
February16th to endNight
14%
631
10%
2042
1%
631
25%
631
9%
1547
March1st to 15thNight
17%
720
14%
1986
4%
720
26%
720
13%
1493
March16th to endNight
16%
768
15%
2112
5%
768
25%
768
14%
1568
April1st to 15thNight
15%
554
12%
1790
5%
554
23%
554
11%
1353
April16th to endNight
18%
540
14%
1620
5%
540
26%
540
15%
1161
May1st to 15thNight
20%
540
9%
1521
4%
540
25%
540
12%
1161
May16th to endNight
17%
561
9%
1496
2%
560
23%
560
14%
1126
June1st to 15thNight
21%
423
7%
1323
4%
423
25%
423
11%
1020
June16th to endNight
26%
360
6%
1260
3%
360
31%
360
12%
927
July1st to 15thNight
28%
340
11%
1190
6%
340
36%
340
18%
762
July16th to endNight
25%
542
8%
1438
4%
509
30%
509
14%
1088
August1st to 15thNight
33%
528
9%
1575
5%
524
36%
524
17%
1134
August16th to endNight
32%
525
12%
1612
6%
525
37%
525
21%
1062
September1st to 15thNight
28%
498
15%
1653
8%
498
38%
498
19%
1070
September16th to endNight
31%
657
21%
1838
11%
657
39%
657
26%
1164
October1st to 15thNight
24%
660
18%
1980
8%
660
33%
660
19%
1316
October16th to endNight
15%
704
14%
2121
4%
704
25%
704
13%
1535
November1st to 15thNight
19%
727
12%
2439
6%
727
27%
727
12%
1766
November16th to endNight
17%
750
13%
2520
4%
750
27%
750
10%
1816
December1st to 15thNight
10%
750
13%
2520
1%
750
23%
750
8%
1850
December16th to endNight
8%
800
11%
2823
1%
800
21%
800
6%
2143

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%8%36%5%3445%7%32%
47628
Night
19%8%36%5%3445%6%32%
46502
TransparencyDay
52%6%12%19%8%
47312
Night
52%6%12%19%8%
46337
SeeingDay
23%25%27%16%5%
7077
Night
22%27%26%17%5%
14805

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%46%5%3445%6%32%
1268
16th to endDay
15%9%47%6%24447%32%
1698
February1st to 15thDay
14%9%48%6%35%46%7%30%
1575
16th to endDay
12%13%5%7%6%35%45%6%28%
1428
March1st to 15thDay
17%11%48%5%34445%29%
1962
16th to endDay
14%10%5%7%5%34445%33%
2112
April1st to 15thDay
16%10%36%7%35%5%6%5%27%
2157
16th to endDay
21%9%16%5%33347%32%
2340
May1st to 15thDay
22%10%37%6%34346%28%
2428
16th to endDay
20%8%38%6%33447%29%
2618
June1st to 15thDay
26%7%36%5%34446%25%
2646
16th to endDay
22%6%35%6%35%46%7%28%
2700
July1st to 15thDay
14%6%35%5%346%6%8%37%
2700
16th to endDay
15%7%35%6%46%6%5%9%30%
2614
August1st to 15thDay
16%6%245%35%6%7%9%34%
2288
16th to endDay
11%6%245%35%6%6%8%39%
2237
September1st to 15thDay
16%5%25%5%2446%7%38%
1975
16th to endDay
15%5%2441335%5%49%
1790
October1st to 15thDay
19%6%24423447%40%
1650
16th to endDay
20%7%35%7%34446%32%
1749
November1st to 15thDay
22%9%35%5%23337%33%
1418
16th to endDay
17%11%26%5%35%46%5%30%
1440
December1st to 15thDay
24%10%35%423347%30%
1440
16th to endDay
21%13%5%5%6%23246%27%
1395
January1st to 15thNight
16%9%36%6%34446%32%
2668
16th to endNight
16%9%45%6%24347%36%
2524
February1st to 15thNight
16%10%46%5%35%45%6%30%
2285
16th to endNight
15%14%5%8%5%36%445%27%
2042
March1st to 15thNight
19%9%46%6%35%45%5%30%
1974
16th to endNight
16%11%47%5%34345%33%
2112
April1st to 15thNight
21%11%46%6%24445%27%
1790
16th to endNight
21%11%25%423446%32%
1620
May1st to 15thNight
25%7%35%5%245%5%5%27%
1521
16th to endNight
18%7%25%6%36%6%7%6%30%
1494
June1st to 15thNight
26%8%45%5%3446%6%24%
1323
16th to endNight
20%7%36%445%5%5%9%27%
1260
July1st to 15thNight
11%6%26%5%36%5%8%9%35%
1260
16th to endNight
16%6%36%6%36%7%7%10%25%
1536
August1st to 15thNight
17%426%5%46%5%7%7%32%
1587
16th to endNight
12%5%25%436%46%9%37%
1612
September1st to 15thNight
15%6%244335%5%8%40%
1653
16th to endNight
13%5%25%423446%48%
1838
October1st to 15thNight
19%6%35%42245%7%39%
1980
16th to endNight
25%8%25%423345%34%
2121
November1st to 15thNight
23%6%26%5%3335%6%32%
2439
16th to endNight
21%8%45%433346%33%
2520
December1st to 15thNight
22%10%36%5%24435%30%
2520
16th to endNight
25%11%5%5%5%2433428%
2823

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
54%6%13%15%8%1
1269
16th to endDay
52%5%10%16%15%
1698
February1st to 15thDay
53%5%13%17%8%1
1578
16th to endDay
57%6%11%16%7%1
1428
March1st to 15thDay
58%5%10%16%8%1
1973
16th to endDay
55%410%18%9%2
2112
April1st to 15thDay
57%5%9%15%10%1
2157
16th to endDay
52%5%10%18%11%1
2340
May1st to 15thDay
58%5%8%17%8%
2428
16th to endDay
56%6%11%19%5%
2622
June1st to 15thDay
59%6%11%15%6%
2646
16th to endDay
55%6%13%17%6%
2700
July1st to 15thDay
42%8%16%22%9%
2541
16th to endDay
51%8%15%18%5%
2451
August1st to 15thDay
47%7%14%22%6%
2275
16th to endDay
42%8%19%23%7%
2237
September1st to 15thDay
44%7%15%20%11%
1975
16th to endDay
37%411%31%14%1
1790
October1st to 15thDay
45%412%27%10%
1650
16th to endDay
53%5%12%19%8%
1749
November1st to 15thDay
54%5%13%15%11%
1418
16th to endDay
55%7%11%15%8%
1440
December1st to 15thDay
56%5%13%18%5%
1440
16th to endDay
61%410%14%9%
1395
January1st to 15thNight
52%7%12%18%8%
2668
16th to endNight
49%5%11%22%10%
2524
February1st to 15thNight
54%412%15%11%
2286
16th to endNight
59%412%13%9%1
2042
March1st to 15thNight
55%5%11%16%9%1
1986
16th to endNight
55%48%19%11%1
2112
April1st to 15thNight
59%5%8%13%10%2
1790
16th to endNight
52%411%16%13%1
1620
May1st to 15thNight
57%6%10%18%7%
1521
16th to endNight
53%6%13%18%6%
1496
June1st to 15thNight
59%6%10%15%5%
1323
16th to endNight
54%8%13%16%6%
1260
July1st to 15thNight
41%9%17%24%7%
1190
16th to endNight
51%11%14%15%6%
1438
August1st to 15thNight
47%10%15%19%6%
1575
16th to endNight
41%8%18%25%6%
1612
September1st to 15thNight
42%7%12%27%10%
1653
16th to endNight
36%6%14%29%12%
1838
October1st to 15thNight
45%413%26%10%
1980
16th to endNight
53%411%20%9%
2121
November1st to 15thNight
53%6%14%16%8%
2439
16th to endNight
53%6%13%17%7%
2520
December1st to 15thNight
56%5%10%20%6%
2520
16th to endNight
61%48%15%8%
2823

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%22%38%9%
75
16th to endDay
19%26%36%12%3
256
February1st to 15thDay
21%31%24%15%6%
236
16th to endDay
24%31%26%14%2
214
March1st to 15thDay
24%31%27%10%4
270
16th to endDay
25%32%25%10%41
288
April1st to 15thDay
24%32%27%12%2
270
16th to endDay
19%32%27%13%6%
270
May1st to 15thDay
32%27%18%16%31
384
16th to endDay
27%27%25%15%3
519
June1st to 15thDay
31%25%23%13%5%
495
16th to endDay
23%23%27%18%5%1
495
July1st to 15thDay
19%17%33%19%8%1
475
16th to endDay
18%16%33%22%8%
466
August1st to 15thDay
18%15%26%27%9%1
297
16th to endDay
14%18%32%22%10%1
268
September1st to 15thDay
18%18%34%21%6%1
255
16th to endDay
19%15%33%22%7%2
249
October1st to 15thDay
25%19%24%16%11%3
225
16th to endDay
26%26%26%13%6%
240
November1st to 15thDay
24%25%24%13%9%2
235
16th to endDay
26%30%23%13%5%
240
December1st to 15thDay
27%32%27%8%2
240
16th to endDay
29%31%26%10%1
115
January1st to 15thNight
23%35%24%14%3
750
16th to endNight
21%33%27%13%3
773
February1st to 15thNight
22%31%29%12%2
704
16th to endNight
26%31%23%15%3
631
March1st to 15thNight
23%31%23%17%3
720
16th to endNight
23%30%25%14%5%
768
April1st to 15thNight
26%29%24%14%3
554
16th to endNight
23%26%28%16%4
540
May1st to 15thNight
27%26%22%17%6%
540
16th to endNight
19%29%29%18%3
561
June1st to 15thNight
23%24%26%23%3
423
16th to endNight
21%21%26%23%6%
360
July1st to 15thNight
16%14%36%26%6%
340
16th to endNight
15%22%30%24%6%
542
August1st to 15thNight
19%13%28%25%11%
528
16th to endNight
14%15%32%29%7%
525
September1st to 15thNight
20%16%32%22%7%
498
16th to endNight
16%18%30%25%7%
657
October1st to 15thNight
21%20%29%19%8%1
660
16th to endNight
29%26%24%14%3
704
November1st to 15thNight
24%25%25%14%7%1
727
16th to endNight
22%34%20%15%5%
750
December1st to 15thNight
28%33%23%12%2
750
16th to endNight
28%34%22%10%3
800
Page generated at 2017-08-13 15:16:15. Version ac04

Copyright 2017 A. Danko


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