Cypress Hills Dark-Sky Preserve - West Block
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Cypress Hills Dark-Sky Preserve - West Block 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
39%
15538
14%
46976
9%
15509
45%
15509
24%
30409

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
28%
897
12%
2685
7%
895
32%
895
17%
1886
January16th to endNight
27%
898
15%
2788
7%
898
37%
898
19%
1826
February1st to 15thNight
38%
697
11%
2288
10%
697
42%
697
20%
1503
February16th to endNight
36%
632
12%
2052
8%
632
41%
632
17%
1413
March1st to 15thNight
35%
720
12%
2044
7%
720
39%
720
23%
1385
March16th to endNight
31%
768
11%
2112
4%
768
37%
768
18%
1565
April1st to 15thNight
34%
545
12%
1737
7%
545
39%
545
21%
1170
April16th to endNight
38%
540
14%
1620
10%
540
41%
540
21%
1111
May1st to 15thNight
48%
539
14%
1451
11%
539
50%
539
28%
952
May16th to endNight
44%
434
7%
1370
6%
433
46%
433
18%
978
June1st to 15thNight
44%
360
4%
1260
3%
360
45%
360
22%
807
June16th to endNight
53%
360
7%
1260
5%
360
55%
360
32%
691
July1st to 15thNight
59%
340
8%
1190
6%
340
62%
340
36%
609
July16th to endNight
62%
388
18%
1250
17%
365
68%
365
46%
585
August1st to 15thNight
64%
539
16%
1559
13%
536
67%
536
40%
887
August16th to endNight
60%
573
24%
1719
18%
573
63%
573
39%
939
September1st to 15thNight
53%
542
19%
1790
17%
542
57%
542
33%
1011
September16th to endNight
49%
716
23%
1995
16%
716
55%
716
38%
1173
October1st to 15thNight
40%
684
18%
2052
9%
684
48%
684
25%
1317
October16th to endNight
38%
731
19%
2216
10%
731
46%
731
24%
1407
November1st to 15thNight
31%
875
17%
2450
8%
875
39%
875
25%
1587
November16th to endNight
28%
900
13%
2520
6%
900
34%
900
23%
1726
December1st to 15thNight
33%
900
10%
2688
6%
900
37%
900
17%
1924
December16th to endNight
32%
960
14%
2880
5%
960
40%
960
19%
1957

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
8%7%36%6%35%5%6%8%38%
48262
Night
6%6%36%5%35%5%6%8%39%
47124
Cloud CoverDay
8%7%36%6%35%5%6%8%38%
48263
Night
6%6%36%6%36%5%6%8%39%
47126
TransparencyDay
41%8%16%22%9%1
47915
Night
38%8%18%22%10%1
46976
SeeingDay
12%8%29%29%16%3
6145
Night
9%10%32%31%14%1
15549

By Month

Percentage Cloud Cover NW (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
39%5%7%8%46%5%7%7%34%
1253
16th to endDay
26%47%8%5%8%7%6%8%32%
1445
February1st to 15thDay
5%6%46%7%5%5%7%7%8%34%
1575
16th to endDay
5%9%6%8%8%5%8%7%7%7%25%
1422
March1st to 15thDay
45%28%7%48%7%8%9%34%
1914
16th to endDay
7%9%5%9%7%5%6%5%7%8%25%
2111
April1st to 15thDay
9%10%46%6%45%5%6%9%30%
2209
16th to endDay
12%11%36%6%25%5%5%6%33%
2340
May1st to 15thDay
9%9%47%6%36%5%5%6%35%
2499
16th to endDay
20%9%36%5%345%5%7%27%
2742
June1st to 15thDay
15%7%36%7%35%5%6%7%30%
2700
16th to endDay
10%5%26%6%36%6%6%8%38%
2700
July1st to 15thDay
43145%35%5%7%9%48%
2700
16th to endDay
42134245%6%9%54%
2833
August1st to 15thDay
6%325%4345%6%7%49%
2391
16th to endDay
7%31432345%8%55%
2483
September1st to 15thDay
13%5%14424345%49%
2169
16th to endDay
12%4133235%5%8%49%
1965
October1st to 15thDay
8%9%47%425%5%6%7%38%
1705
16th to endDay
6%7%37%5%45%5%6%9%39%
1642
November1st to 15thDay
5%8%35%6%47%5%5%8%38%
1408
16th to endDay
5%8%47%5%36%7%7%7%36%
1440
December1st to 15thDay
311%28%9%410%8%5%8%25%
1272
16th to endDay
49%47%8%47%5%7%9%30%
1344
January1st to 15thNight
47%48%6%46%5%7%10%33%
2685
16th to endNight
26%37%6%5%6%7%7%9%35%
2788
February1st to 15thNight
46%46%6%5%7%6%6%9%35%
2277
16th to endNight
36%48%9%5%8%6%7%9%29%
2052
March1st to 15thNight
36%37%6%5%7%6%6%10%35%
2044
16th to endNight
8%9%48%7%36%6%7%8%27%
2109
April1st to 15thNight
8%8%47%6%45%5%6%8%34%
1737
16th to endNight
11%8%46%6%26%5%6%6%35%
1620
May1st to 15thNight
8%7%36%5%35%45%7%42%
1450
16th to endNight
15%6%5%6%6%35%5%5%6%31%
1370
June1st to 15thNight
13%6%16%5%35%5%5%7%40%
1260
16th to endNight
6%315%3345%5%9%48%
1260
July1st to 15thNight
43143345%6%7%55%
1260
16th to endNight
31122235%5%10%59%
1335
August1st to 15thNight
6%315%32345%8%54%
1567
16th to endNight
6%41442445%7%53%
1719
September1st to 15thNight
9%6%24424336%51%
1790
16th to endNight
8%5%1443345%7%51%
1995
October1st to 15thNight
8%7%35%5%3446%8%41%
2052
16th to endNight
5%7%46%5%35%5%5%8%42%
2216
November1st to 15thNight
5%6%245%36%6%6%9%42%
2450
16th to endNight
5%8%47%6%35%6%6%8%36%
2520
December1st to 15thNight
28%48%6%5%8%7%7%9%30%
2688
16th to endNight
48%47%5%45%6%8%9%34%
2880

Percentage Cloud Cover SW (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
39%5%7%8%5%5%5%7%8%32%
1253
16th to endDay
27%48%7%6%8%8%6%10%31%
1445
February1st to 15thDay
47%46%8%47%8%7%8%33%
1575
16th to endDay
5%9%6%9%8%47%6%8%8%24%
1422
March1st to 15thDay
35%28%7%48%6%8%9%34%
1914
16th to endDay
8%9%49%8%47%6%7%9%25%
2112
April1st to 15thDay
9%11%46%7%35%6%6%9%30%
2209
16th to endDay
13%10%37%6%245%5%6%34%
2340
May1st to 15thDay
9%10%46%5%36%5%5%5%36%
2499
16th to endDay
19%9%35%6%445%5%7%27%
2742
June1st to 15thDay
16%7%37%6%45%5%5%8%30%
2700
16th to endDay
9%5%35%5%35%6%6%9%38%
2700
July1st to 15thDay
43145%35%5%7%10%48%
2700
16th to endDay
421342446%9%54%
2833
August1st to 15thDay
6%4244345%5%9%49%
2391
16th to endDay
7%31332335%8%56%
2483
September1st to 15thDay
12%5%14423346%49%
2169
16th to endDay
12%41332345%8%49%
1965
October1st to 15thDay
8%9%47%425%5%6%7%38%
1705
16th to endDay
6%6%37%7%345%6%9%39%
1642
November1st to 15thDay
5%8%35%6%46%5%5%8%38%
1408
16th to endDay
5%7%5%7%5%46%7%6%8%34%
1440
December1st to 15thDay
410%37%10%5%9%7%6%8%25%
1272
16th to endDay
49%48%8%46%6%7%9%29%
1344
January1st to 15thNight
47%5%7%6%46%6%6%11%32%
2685
16th to endNight
26%47%8%47%5%8%10%34%
2788
February1st to 15thNight
37%37%7%6%6%6%7%9%34%
2277
16th to endNight
36%5%8%9%5%7%6%8%9%28%
2052
March1st to 15thNight
36%37%6%5%8%6%6%10%35%
2044
16th to endNight
8%8%48%8%27%6%8%7%27%
2112
April1st to 15thNight
7%7%5%7%6%36%5%6%9%34%
1737
16th to endNight
11%9%47%435%5%6%7%35%
1620
May1st to 15thNight
8%8%25%5%35%5%5%6%43%
1450
16th to endNight
15%7%46%6%35%5%5%6%32%
1369
June1st to 15thNight
13%6%25%5%35%6%46%40%
1260
16th to endNight
6%324425%5%6%9%48%
1260
July1st to 15thNight
5%3143245%5%8%55%
1260
16th to endNight
311331346%10%59%
1335
August1st to 15thNight
6%42432445%8%54%
1567
16th to endNight
6%325%32446%7%53%
1719
September1st to 15thNight
9%6%14424446%51%
1790
16th to endNight
8%415%42335%8%50%
1995
October1st to 15thNight
8%7%26%43446%8%41%
2052
16th to endNight
5%7%5%6%5%35%5%6%8%42%
2216
November1st to 15thNight
5%6%245%37%5%7%8%42%
2450
16th to endNight
5%9%47%6%35%6%7%8%35%
2520
December1st to 15thNight
29%5%8%7%5%8%6%7%9%29%
2688
16th to endNight
48%47%6%36%6%8%10%32%
2880

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
46%12%17%19%31
1253
16th to endDay
43%12%19%18%41
1445
February1st to 15thDay
43%10%20%18%6%
1575
16th to endDay
53%10%15%14%6%
1422
March1st to 15thDay
39%14%22%18%4
1914
16th to endDay
52%9%16%17%3
2112
April1st to 15thDay
47%9%15%21%5%
2209
16th to endDay
48%7%15%22%5%1
2340
May1st to 15thDay
46%7%15%22%7%
2499
16th to endDay
53%7%14%17%5%
2747
June1st to 15thDay
50%8%14%18%7%
2700
16th to endDay
38%8%18%24%8%
2700
July1st to 15thDay
28%7%17%28%15%1
2541
16th to endDay
23%7%14%29%21%3
2655
August1st to 15thDay
29%7%19%26%14%2
2375
16th to endDay
25%5%14%30%22%3
2483
September1st to 15thDay
35%413%24%17%5%
2169
16th to endDay
31%6%14%30%15%1
1965
October1st to 15thDay
41%8%17%21%9%
1705
16th to endDay
39%8%19%23%9%
1642
November1st to 15thDay
41%10%19%21%6%
1408
16th to endDay
43%9%20%18%7%
1440
December1st to 15thDay
50%12%17%17%1
1272
16th to endDay
46%9%20%19%4
1344
January1st to 15thNight
41%13%19%18%41
2685
16th to endNight
38%10%20%19%7%1
2788
February1st to 15thNight
40%9%21%18%8%1
2288
16th to endNight
46%8%15%20%7%1
2052
March1st to 15thNight
40%10%22%20%6%
2044
16th to endNight
50%9%15%19%5%
2112
April1st to 15thNight
44%7%17%21%8%
1737
16th to endNight
46%6%14%20%10%2
1620
May1st to 15thNight
38%7%11%29%12%
1451
16th to endNight
50%6%15%17%8%
1370
June1st to 15thNight
41%7%17%23%9%
1260
16th to endNight
30%5%19%31%12%
1260
July1st to 15thNight
24%7%13%32%19%3
1190
16th to endNight
16%7%14%31%24%5%
1250
August1st to 15thNight
26%6%17%31%14%3
1559
16th to endNight
27%5%12%24%25%5%
1719
September1st to 15thNight
33%311%25%16%8%
1790
16th to endNight
30%415%29%17%2
1995
October1st to 15thNight
38%7%18%23%11%1
2052
16th to endNight
36%8%17%26%10%
2216
November1st to 15thNight
34%10%21%21%10%1
2450
16th to endNight
42%8%24%14%8%
2520
December1st to 15thNight
44%12%21%16%4
2688
16th to endNight
40%11%21%21%5%
2880

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
11%8%26%16%25%11%
60
16th to endDay
7%11%28%31%15%4
69
February1st to 15thDay
12%12%41%23%7%3
90
16th to endDay
11%7%32%37%11%1
81
March1st to 15thDay
9%12%46%24%6%
243
16th to endDay
10%11%46%22%8%
288
April1st to 15thDay
11%18%31%28%9%
269
16th to endDay
21%10%27%26%12%1
270
May1st to 15thDay
13%9%25%31%15%4
456
16th to endDay
20%9%26%22%18%3
517
June1st to 15thDay
16%10%25%26%17%2
495
16th to endDay
10%8%28%27%21%3
495
July1st to 15thDay
6%323%40%22%3
475
16th to endDay
7%5%27%35%18%5%
515
August1st to 15thDay
6%5%23%37%22%4
366
16th to endDay
9%6%22%35%22%3
332
September1st to 15thDay
19%427%29%15%3
315
16th to endDay
13%9%29%28%14%5%
300
October1st to 15thDay
22%10%27%26%14%
107
16th to endDay
13%13%22%32%14%3
96
November1st to 15thDay
13%7%36%30%12%
90
16th to endDay
411%40%23%15%5%
90
December1st to 15thDay
8%14%37%27%6%6%
62
16th to endDay
14%7%37%26%9%4
64
January1st to 15thNight
7%18%38%22%10%1
900
16th to endNight
418%39%24%10%2
898
February1st to 15thNight
7%14%30%29%15%2
704
16th to endNight
5%11%34%31%13%3
632
March1st to 15thNight
6%9%40%30%10%1
720
16th to endNight
12%8%35%30%10%2
768
April1st to 15thNight
10%9%36%30%11%1
545
16th to endNight
16%8%27%32%14%1
540
May1st to 15thNight
12%9%23%32%20%1
540
16th to endNight
16%7%20%33%17%3
434
June1st to 15thNight
16%5%28%30%16%1
360
16th to endNight
8%6%28%35%18%1
360
July1st to 15thNight
7%324%45%17%1
340
16th to endNight
45%25%39%23%1
388
August1st to 15thNight
9%220%39%26%2
539
16th to endNight
7%5%21%37%26%1
573
September1st to 15thNight
14%423%32%21%3
542
16th to endNight
10%5%28%33%17%4
716
October1st to 15thNight
13%8%29%29%15%1
684
16th to endNight
8%11%33%33%11%1
731
November1st to 15thNight
8%14%40%27%7%1
875
16th to endNight
10%10%42%29%6%
900
December1st to 15thNight
6%14%35%30%10%2
900
16th to endNight
8%13%35%28%11%2
960
Page generated at 2017-10-07 12:07:45. Version ac04

Copyright 2017 A. Danko


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