Cypress Hills Dark-Sky Preserve - CHICO
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Cypress Hills Dark-Sky Preserve - CHICO 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%
15512
14%
46980
9%
15484
44%
15484
24%
30200

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
27%
897
12%
2685
7%
895
32%
895
18%
1868
January16th to endNight
26%
888
15%
2791
7%
888
35%
888
18%
1854
February1st to 15thNight
36%
697
12%
2288
11%
697
40%
697
21%
1496
February16th to endNight
34%
632
11%
2052
7%
632
39%
632
18%
1396
March1st to 15thNight
35%
720
12%
2043
6%
720
40%
720
24%
1375
March16th to endNight
31%
768
11%
2112
3%
768
37%
768
18%
1550
April1st to 15thNight
35%
551
13%
1733
7%
551
40%
551
20%
1180
April16th to endNight
38%
540
14%
1620
10%
540
42%
540
21%
1105
May1st to 15thNight
47%
539
14%
1461
11%
539
49%
539
30%
932
May16th to endNight
42%
422
8%
1357
7%
421
44%
421
18%
949
June1st to 15thNight
43%
360
4%
1260
3%
360
44%
360
22%
795
June16th to endNight
52%
360
7%
1260
5%
360
54%
360
33%
680
July1st to 15thNight
57%
340
7%
1190
5%
340
61%
340
36%
607
July16th to endNight
61%
376
19%
1239
17%
354
68%
354
46%
571
August1st to 15thNight
63%
539
16%
1570
13%
536
68%
536
40%
872
August16th to endNight
60%
573
25%
1719
18%
573
64%
573
39%
942
September1st to 15thNight
52%
552
19%
1793
17%
552
56%
552
33%
1009
September16th to endNight
50%
716
24%
1986
16%
716
56%
716
38%
1170
October1st to 15thNight
41%
684
18%
2052
9%
684
50%
684
26%
1298
October16th to endNight
37%
723
18%
2219
10%
723
45%
723
24%
1378
November1st to 15thNight
31%
875
16%
2450
7%
875
39%
875
26%
1590
November16th to endNight
28%
900
14%
2520
7%
900
33%
900
23%
1720
December1st to 15thNight
32%
900
9%
2700
6%
900
34%
900
17%
1931
December16th to endNight
30%
960
13%
2880
5%
960
38%
960
20%
1932

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%7%37%
48252
Night
6%7%37%6%36%6%6%8%37%
47127
Cloud CoverDay
8%7%36%6%35%5%6%7%37%
48253
Night
6%7%37%6%46%5%6%8%37%
47129
TransparencyDay
41%6%17%23%9%1
47904
Night
39%6%18%22%10%1
46980
SeeingDay
13%8%28%29%16%3
6136
Night
10%10%32%30%14%2
15523

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
310%6%10%7%5%7%5%5%6%29%
1253
16th to endDay
27%39%9%5%9%5%6%8%31%
1440
February1st to 15thDay
49%47%9%5%7%6%7%7%30%
1575
16th to endDay
411%8%9%7%5%6%6%6%7%25%
1422
March1st to 15thDay
46%38%8%5%7%7%8%9%32%
1914
16th to endDay
6%10%5%9%8%5%8%6%7%8%24%
2111
April1st to 15thDay
8%10%48%7%46%7%5%7%29%
2214
16th to endDay
12%11%38%5%35%5%46%33%
2340
May1st to 15thDay
10%9%47%6%45%5%5%5%35%
2490
16th to endDay
20%9%46%5%345%5%7%28%
2755
June1st to 15thDay
15%7%37%6%35%5%6%7%29%
2700
16th to endDay
11%5%25%5%36%5%7%8%39%
2700
July1st to 15thDay
5%415%425%47%10%48%
2700
16th to endDay
42133245%6%8%56%
2844
August1st to 15thDay
6%4244245%6%8%50%
2379
16th to endDay
8%41331345%7%55%
2483
September1st to 15thDay
12%7%24423345%49%
2163
16th to endDay
11%413335%45%8%49%
1973
October1st to 15thDay
9%8%27%6%35%5%6%6%37%
1705
16th to endDay
5%8%38%6%36%46%7%38%
1642
November1st to 15thDay
410%37%8%35%5%6%7%35%
1408
16th to endDay
5%8%5%8%7%37%6%6%8%32%
1437
December1st to 15thDay
411%410%9%5%9%7%7%8%22%
1260
16th to endDay
38%5%8%8%5%8%6%7%9%27%
1344
January1st to 15thNight
37%5%9%8%47%6%7%8%29%
2685
16th to endNight
27%5%9%8%47%6%7%8%31%
2791
February1st to 15thNight
46%47%8%5%8%7%6%9%30%
2277
16th to endNight
37%5%10%9%48%7%6%8%27%
2052
March1st to 15thNight
45%37%7%47%8%7%10%32%
2043
16th to endNight
7%10%49%8%46%5%7%8%26%
2109
April1st to 15thNight
9%7%48%6%45%6%6%9%30%
1733
16th to endNight
10%9%38%7%44447%34%
1620
May1st to 15thNight
8%8%25%5%25%6%5%6%43%
1460
16th to endNight
16%7%48%6%35%447%31%
1357
June1st to 15thNight
14%6%25%425%5%48%39%
1260
16th to endNight
9%31442447%10%46%
1260
July1st to 15thNight
5%3134235%7%8%53%
1260
16th to endNight
33132345%6%7%58%
1323
August1st to 15thNight
6%3245%3346%8%52%
1578
16th to endNight
6%414324447%53%
1719
September1st to 15thNight
9%7%2442444452%
1793
16th to endNight
7%43343345%8%50%
1986
October1st to 15thNight
9%8%26%435%5%7%8%39%
2052
16th to endNight
5%7%36%6%45%5%6%8%39%
2219
November1st to 15thNight
47%36%6%37%5%7%7%38%
2450
16th to endNight
49%48%7%46%6%6%7%34%
2520
December1st to 15thNight
29%5%10%9%5%7%7%7%10%23%
2700
16th to endNight
48%47%7%46%6%8%9%30%
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
38%6%10%6%49%6%5%6%30%
1253
16th to endDay
27%47%10%5%8%7%5%9%31%
1440
February1st to 15thDay
48%47%8%47%7%7%8%30%
1575
16th to endDay
411%7%9%8%5%6%6%7%7%25%
1422
March1st to 15thDay
36%38%7%5%7%7%8%10%32%
1914
16th to endDay
7%10%5%9%8%5%7%7%6%8%24%
2112
April1st to 15thDay
9%11%47%6%46%6%7%7%28%
2214
16th to endDay
13%10%47%6%34446%33%
2340
May1st to 15thDay
10%10%47%7%35%45%5%34%
2490
16th to endDay
20%8%36%5%35%5%5%7%27%
2755
June1st to 15thDay
16%7%47%6%36%5%6%7%29%
2700
16th to endDay
11%5%25%6%36%6%7%7%38%
2700
July1st to 15thDay
6%3144345%6%10%47%
2700
16th to endDay
5%2134335%6%7%56%
2844
August1st to 15thDay
6%5%145%345%6%7%50%
2379
16th to endDay
8%41332345%7%54%
2483
September1st to 15thDay
13%7%24423346%49%
2163
16th to endDay
11%5%133245%5%8%48%
1973
October1st to 15thDay
8%8%37%5%35%5%6%6%37%
1705
16th to endDay
6%8%47%7%345%6%7%38%
1642
November1st to 15thDay
49%5%6%8%45%45%7%36%
1408
16th to endDay
5%8%5%7%6%47%6%7%7%33%
1437
December1st to 15thDay
310%49%9%5%9%8%6%8%23%
1260
16th to endDay
39%48%8%48%6%9%8%28%
1344
January1st to 15thNight
38%49%8%46%6%8%9%30%
2685
16th to endNight
16%49%9%5%7%6%7%8%32%
2791
February1st to 15thNight
47%37%6%5%8%7%7%9%31%
2277
16th to endNight
37%410%9%48%7%7%8%27%
2052
March1st to 15thNight
46%38%8%5%6%7%7%10%32%
2043
16th to endNight
8%9%48%9%47%5%7%8%26%
2112
April1st to 15thNight
8%8%47%7%46%6%5%8%31%
1733
16th to endNight
10%9%37%7%4445%7%34%
1620
May1st to 15thNight
8%9%35%4345%6%6%42%
1460
16th to endNight
16%8%38%7%35%437%31%
1356
June1st to 15thNight
14%6%36%4245%47%39%
1260
16th to endNight
8%5%144245%8%9%46%
1260
July1st to 15thNight
5%4143246%5%8%53%
1260
16th to endNight
32123245%6%8%58%
1323
August1st to 15thNight
6%325%42346%8%52%
1578
16th to endNight
7%42432445%7%53%
1719
September1st to 15thNight
9%7%24423435%51%
1793
16th to endNight
7%5%2442345%7%50%
1986
October1st to 15thNight
8%8%35%5%245%7%8%39%
2052
16th to endNight
5%7%36%7%35%5%5%9%39%
2219
November1st to 15thNight
5%6%36%6%47%6%6%8%39%
2450
16th to endNight
5%9%48%6%36%6%6%8%34%
2520
December1st to 15thNight
29%5%9%8%6%8%6%8%10%25%
2700
16th to endNight
47%5%7%7%46%7%7%10%31%
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
48%9%16%19%31
1253
16th to endDay
45%8%20%18%41
1440
February1st to 15thDay
44%8%21%18%6%
1575
16th to endDay
54%7%16%15%6%
1422
March1st to 15thDay
40%11%25%18%4
1914
16th to endDay
52%7%18%17%4
2112
April1st to 15thDay
48%6%15%22%5%
2214
16th to endDay
49%416%22%5%1
2340
May1st to 15thDay
48%316%23%8%
2490
16th to endDay
54%5%16%17%6%
2760
June1st to 15thDay
51%5%14%20%8%
2700
16th to endDay
39%6%18%25%8%
2700
July1st to 15thDay
29%5%17%29%16%1
2541
16th to endDay
23%5%14%29%21%4
2665
August1st to 15thDay
29%6%18%28%15%2
2363
16th to endDay
26%312%32%21%2
2483
September1st to 15thDay
36%312%25%17%5%
2163
16th to endDay
31%5%14%31%15%1
1973
October1st to 15thDay
42%6%18%22%9%
1705
16th to endDay
40%6%18%24%8%
1642
November1st to 15thDay
43%8%18%22%6%
1408
16th to endDay
45%7%20%17%8%
1437
December1st to 15thDay
51%11%19%16%1
1260
16th to endDay
46%8%22%18%3
1344
January1st to 15thNight
43%10%21%18%41
2685
16th to endNight
41%9%19%19%7%1
2791
February1st to 15thNight
42%7%21%18%8%1
2288
16th to endNight
47%7%17%19%7%1
2052
March1st to 15thNight
40%8%23%21%6%
2043
16th to endNight
51%6%15%20%5%
2112
April1st to 15thNight
46%6%16%21%8%
1733
16th to endNight
47%5%13%22%9%1
1620
May1st to 15thNight
39%413%29%12%
1461
16th to endNight
52%415%18%8%
1357
June1st to 15thNight
42%5%17%24%8%
1260
16th to endNight
29%5%19%31%12%1
1260
July1st to 15thNight
25%5%12%33%18%3
1190
16th to endNight
19%414%31%23%6%
1239
August1st to 15thNight
27%415%33%15%3
1570
16th to endNight
28%410%26%25%4
1719
September1st to 15thNight
33%311%26%16%8%
1793
16th to endNight
30%414%30%17%2
1986
October1st to 15thNight
38%6%18%23%11%1
2052
16th to endNight
37%7%19%26%9%
2219
November1st to 15thNight
37%7%22%20%10%
2450
16th to endNight
43%6%25%14%9%
2520
December1st to 15thNight
46%10%21%16%4
2700
16th to endNight
42%8%22%20%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%10%28%15%21%13%
60
16th to endDay
413%28%37%11%4
67
February1st to 15thDay
13%16%34%25%6%3
90
16th to endDay
12%7%33%33%12%1
81
March1st to 15thDay
11%9%46%25%7%
252
16th to endDay
12%11%44%21%7%1
288
April1st to 15thDay
12%18%28%31%7%1
269
16th to endDay
22%9%27%23%13%2
270
May1st to 15thDay
13%10%24%29%15%6%
447
16th to endDay
21%8%21%24%19%4
517
June1st to 15thDay
17%10%24%27%17%2
495
16th to endDay
11%8%30%24%21%4
495
July1st to 15thDay
7%323%40%22%3
475
16th to endDay
7%6%27%33%19%5%
515
August1st to 15thDay
8%422%37%21%5%
354
16th to endDay
9%6%23%37%21%3
332
September1st to 15thDay
18%6%28%27%15%3
315
16th to endDay
12%10%28%28%13%5%
308
October1st to 15thDay
24%9%24%25%16%
107
16th to endDay
12%9%23%32%19%2
96
November1st to 15thDay
11%11%34%32%10%1
90
16th to endDay
6%12%38%23%13%5%
89
December1st to 15thDay
5%16%36%23%8%10%
60
16th to endDay
9%12%34%25%12%6%
64
January1st to 15thNight
8%18%37%23%10%1
900
16th to endNight
417%40%24%10%1
888
February1st to 15thNight
8%12%32%26%16%3
704
16th to endNight
5%11%35%30%14%3
632
March1st to 15thNight
7%9%40%30%11%1
720
16th to endNight
13%10%34%28%11%2
768
April1st to 15thNight
13%10%33%29%11%1
551
16th to endNight
17%6%28%31%15%
540
May1st to 15thNight
12%7%24%32%20%2
540
16th to endNight
18%7%19%32%18%3
422
June1st to 15thNight
18%7%25%31%15%1
360
16th to endNight
11%6%24%37%17%2
360
July1st to 15thNight
9%422%45%17%1
340
16th to endNight
5%425%40%22%1
376
August1st to 15thNight
8%220%40%26%1
539
16th to endNight
10%419%38%26%1
573
September1st to 15thNight
14%424%31%21%3
552
16th to endNight
10%5%28%33%17%4
716
October1st to 15thNight
14%8%28%31%15%1
684
16th to endNight
9%12%33%31%12%
723
November1st to 15thNight
9%14%39%27%8%
875
16th to endNight
9%10%43%29%6%
900
December1st to 15thNight
7%12%36%28%12%2
900
16th to endNight
8%13%36%26%10%3
960
Page generated at 2017-10-07 12:07:51. Version ac04

Copyright 2017 A. Danko


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