Campbell Valley Regional Park
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Campbell Valley Regional Park clear sky chart from 2005-11-06 to 2024-01-13.

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 Type	Minimum conditions for hour to be usable				Out of hours
	Clear of Clouds	Transparency	Seeing	Sky Brightness
Planetary:	50%	(no limit)	Average	(no limit)	Nighttime Hours
Deep Sky:	70%	Average	(no limit)	5.9	Nighttime Hours
CCD Imaging:	70%	Below Average	Poor	(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

By Month

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 Forecast	Data Points
Cloud Cover	Day	24% 8% 3 6% 5% 3 4 4 5% 6% 33%	74760
	Night	28% 8% 3 6% 5% 3 4 4 4 5% 30%	74994
Transparency	Day	36% 39% 9% 10% 4 1	74451
	Night	39% 39% 9% 9% 4 1	74822
Seeing	Day	22% 7% 18% 26% 21% 6%	14154
	Night	29% 7% 16% 23% 20% 5%	22554

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
Month	Days in Month		Occurrence of each Forecast	Data Points
January	1st to 10th	Day	44% 9% 4 6% 6% 3 4 3 4 4 13%	1329
	11th to 20th	Day	35% 11% 3 6% 7% 2 3 4 5% 5% 18%	1298
	21st to end	Day	37% 11% 3 7% 6% 3 4 4 4 5% 18%	1598
February	1st to 10th	Day	35% 11% 3 8% 5% 3 5% 3 4 5% 18%	1620
	11th to 20th	Day	31% 10% 3 6% 6% 3 5% 4 5% 5% 21%	1575
	21st to end	Day	26% 13% 4 7% 6% 3 4 4 5% 5% 23%	1360
March	1st to 10th	Day	31% 12% 4 7% 6% 3 4 4 5% 6% 20%	1844
	11th to 20th	Day	32% 11% 4 7% 6% 3 4 3 3 6% 20%	1980
	21st to end	Day	29% 11% 3 7% 6% 4 4 5% 4 6% 21%	2244
April	1st to 10th	Day	28% 10% 4 7% 6% 3 5% 4 4 7% 21%	2160
	11th to 20th	Day	23% 10% 3 6% 7% 4 5% 4 5% 6% 26%	2200
	21st to end	Day	24% 8% 4 6% 6% 3 4 6% 5% 6% 28%	2401
May	1st to 10th	Day	18% 7% 2 7% 4 3 5% 5% 5% 7% 36%	2520
	11th to 20th	Day	17% 7% 3 7% 6% 3 4 6% 5% 8% 34%	2477
	21st to end	Day	19% 8% 4 6% 6% 3 5% 4 5% 7% 33%	2735
June	1st to 10th	Day	22% 6% 2 7% 5% 4 4 4 6% 7% 32%	2700
	11th to 20th	Day	23% 7% 3 7% 6% 3 5% 5% 5% 8% 29%	2700
	21st to end	Day	14% 6% 2 5% 6% 4 5% 5% 5% 7% 41%	2700
July	1st to 10th	Day	13% 4 2 4 4 3 3 3 5% 7% 51%	2700
	11th to 20th	Day	10% 4 2 3 3 3 4 4 5% 6% 55%	2700
	21st to end	Day	8% 2 1 2 3 2 2 3 5% 5% 66%	2759
August	1st to 10th	Day	10% 4 2 4 4 1 3 3 4 6% 59%	2499
	11th to 20th	Day	8% 4 2 3 4 2 3 4 5% 6% 59%	2298
	21st to end	Day	14% 5% 2 5% 4 3 4 4 4 7% 48%	2502
September	1st to 10th	Day	14% 6% 3 5% 5% 2 4 3 4 6% 48%	2160
	11th to 20th	Day	18% 6% 3 6% 6% 2 4 4 4 7% 40%	2160
	21st to end	Day	25% 6% 2 6% 5% 2 3 4 5% 5% 36%	1897
October	1st to 10th	Day	24% 7% 3 6% 4 3 4 5% 4 7% 33%	1800
	11th to 20th	Day	30% 8% 4 7% 5% 3 3 5% 5% 7% 24%	1800
	21st to end	Day	33% 8% 3 6% 5% 3 3 5% 5% 6% 23%	1845
November	1st to 10th	Day	40% 7% 3 5% 6% 5% 3 4 4 5% 18%	1488
	11th to 20th	Day	36% 11% 3 5% 5% 2 3 3 4 4 23%	1520
	21st to end	Day	37% 10% 5% 6% 5% 3 3 4 5% 4 18%	1520
December	1st to 10th	Day	34% 11% 3 6% 5% 2 3 3 4 3 25%	1520
	11th to 20th	Day	37% 13% 4 6% 6% 2 4 5% 4 5% 15%	1709
	21st to end	Day	35% 15% 4 9% 6% 4 4 3 4 4 12%	2442
January	1st to 10th	Night	43% 12% 4 6% 5% 2 3 3 3 4 17%	2836
	11th to 20th	Night	38% 11% 3 5% 4 2 3 4 4 6% 20%	2720
	21st to end	Night	36% 11% 4 6% 4 2 4 2 3 5% 21%	2756
February	1st to 10th	Night	38% 10% 4 6% 4 3 4 3 4 5% 21%	2340
	11th to 20th	Night	31% 11% 3 7% 5% 3 3 3 4 4 25%	2272
	21st to end	Night	29% 11% 4 6% 5% 3 4 4 4 6% 26%	1895
March	1st to 10th	Night	30% 10% 3 5% 5% 3 5% 4 4 5% 25%	2112
	11th to 20th	Night	34% 9% 3 6% 5% 3 4 4 4 5% 23%	1979
	21st to end	Night	33% 12% 4 7% 5% 3 4 4 5% 5% 19%	2111
April	1st to 10th	Night	28% 10% 4 7% 6% 3 4 4 6% 6% 23%	1800
	11th to 20th	Night	25% 9% 3 7% 6% 4 4 5% 4 5% 28%	1709
	21st to end	Night	27% 8% 4 7% 7% 3 4 4 4 6% 26%	1558
May	1st to 10th	Night	19% 6% 2 6% 5% 3 5% 5% 4 7% 39%	1440
	11th to 20th	Night	15% 6% 3 5% 5% 3 6% 6% 8% 7% 35%	1416
	21st to end	Night	18% 6% 3 6% 5% 4 5% 5% 6% 7% 36%	1536
June	1st to 10th	Night	21% 7% 3 7% 6% 3 5% 4 6% 6% 32%	1260
	11th to 20th	Night	19% 8% 4 7% 6% 4 5% 5% 6% 6% 29%	1260
	21st to end	Night	14% 5% 2 6% 5% 3 4 4 6% 7% 44%	1260
July	1st to 10th	Night	11% 4 2 6% 6% 3 3 3 4 5% 54%	1260
	11th to 20th	Night	10% 4 2 3 4 1 3 3 3 5% 61%	1260
	21st to end	Night	5% 2 1 3 2 2 3 4 4 5% 69%	1557
August	1st to 10th	Night	8% 3 2 3 3 1 3 4 4 6% 63%	1438
	11th to 20th	Night	6% 3 1 4 3 1 2 3 5% 9% 62%	1602
	21st to end	Night	9% 5% 2 4 6% 2 5% 4 7% 8% 47%	1854
September	1st to 10th	Night	10% 3 2 4 4 3 4 4 5% 7% 56%	1800
	11th to 20th	Night	19% 5% 2 6% 5% 3 4 3 4 6% 43%	1800
	21st to end	Night	20% 5% 3 6% 5% 3 3 4 4 6% 40%	2059
October	1st to 10th	Night	21% 6% 2 5% 6% 3 5% 5% 4 5% 39%	2160
	11th to 20th	Night	29% 8% 3 5% 5% 2 3 4 4 6% 30%	2160
	21st to end	Night	33% 7% 3 5% 5% 2 4 4 3 6% 30%	2509
November	1st to 10th	Night	39% 9% 3 6% 6% 3 5% 3 3 5% 18%	2590
	11th to 20th	Night	38% 8% 3 5% 4 3 4 3 4 4 24%	2660
	21st to end	Night	37% 9% 4 6% 6% 3 4 3 3 4 19%	2660
December	1st to 10th	Night	33% 8% 3 5% 5% 2 5% 4 4 5% 25%	2660
	11th to 20th	Night	42% 13% 4 7% 5% 3 3 3 3 4 14%	3491
	21st to end	Night	37% 13% 5% 7% 6% 2 4 3 3 4 16%	5214

Transparency (when cloud cover <= 30%)
Color Meanings: Too cloudy to forecast Poor Below Average Average Above average Transparent
Month	Days in Month		Occurrence of each Forecast	Data Points
January	1st to 10th	Day	52% 40% 4 3 1	1329
	11th to 20th	Day	43% 44% 5% 5% 2 1	1298
	21st to end	Day	45% 39% 6% 7% 3	1598
February	1st to 10th	Day	47% 39% 7% 5% 3	1620
	11th to 20th	Day	42% 39% 6% 7% 5% 1	1584
	21st to end	Day	45% 40% 6% 6% 3	1360
March	1st to 10th	Day	45% 39% 7% 6% 2 1	1844
	11th to 20th	Day	46% 37% 6% 8% 2	1980
	21st to end	Day	45% 39% 7% 8% 1	2244
April	1st to 10th	Day	45% 39% 10% 6% 1	2160
	11th to 20th	Day	41% 38% 7% 7% 6% 1	2200
	21st to end	Day	39% 39% 9% 7% 5% 1	2401
May	1st to 10th	Day	37% 40% 9% 10% 4	2520
	11th to 20th	Day	32% 41% 10% 12% 5%	2480
	21st to end	Day	40% 40% 8% 10% 2	2736
June	1st to 10th	Day	38% 39% 10% 8% 3 2	2700
	11th to 20th	Day	40% 41% 11% 6% 1	2700
	21st to end	Day	31% 40% 11% 11% 6% 1	2700
July	1st to 10th	Day	21% 41% 12% 17% 8% 1	2626
	11th to 20th	Day	21% 39% 13% 21% 6% 1	2619
	21st to end	Day	15% 39% 12% 21% 10% 3	2606
August	1st to 10th	Day	21% 39% 15% 19% 5% 1	2482
	11th to 20th	Day	18% 38% 14% 17% 10% 3	2298
	21st to end	Day	25% 39% 13% 17% 5% 1	2502
September	1st to 10th	Day	22% 38% 12% 15% 9% 4	2160
	11th to 20th	Day	28% 39% 9% 13% 10% 1	2160
	21st to end	Day	33% 40% 8% 11% 6% 1	1897
October	1st to 10th	Day	33% 39% 11% 10% 7%	1800
	11th to 20th	Day	38% 40% 10% 9% 2 1	1800
	21st to end	Day	40% 40% 7% 6% 6%	1845
November	1st to 10th	Day	45% 42% 6% 4 2 1	1488
	11th to 20th	Day	46% 41% 5% 6% 2 1	1520
	21st to end	Day	46% 41% 6% 6% 2 1	1520
December	1st to 10th	Day	43% 43% 3 6% 4	1520
	11th to 20th	Day	48% 35% 10% 6% 1 1	1712
	21st to end	Day	59% 30% 7% 4 1	2442
January	1st to 10th	Night	51% 41% 4 4 1	2836
	11th to 20th	Night	43% 42% 5% 6% 3 1	2720
	21st to end	Night	43% 38% 6% 8% 4 1	2756
February	1st to 10th	Night	46% 38% 7% 6% 2	2340
	11th to 20th	Night	41% 39% 6% 8% 5% 1	2274
	21st to end	Night	45% 37% 6% 8% 3	1895
March	1st to 10th	Night	41% 39% 9% 8% 2	2112
	11th to 20th	Night	45% 38% 7% 7% 3	1980
	21st to end	Night	46% 38% 9% 6% 1	2111
April	1st to 10th	Night	41% 41% 10% 7% 1	1800
	11th to 20th	Night	37% 39% 8% 9% 5% 2	1709
	21st to end	Night	41% 40% 8% 7% 4	1558
May	1st to 10th	Night	32% 40% 11% 12% 5%	1440
	11th to 20th	Night	30% 40% 13% 12% 6%	1416
	21st to end	Night	36% 39% 12% 10% 3	1536
June	1st to 10th	Night	38% 39% 11% 7% 4 2	1260
	11th to 20th	Night	37% 42% 12% 8% 1	1260
	21st to end	Night	27% 39% 14% 12% 5% 3	1260
July	1st to 10th	Night	21% 40% 9% 19% 8% 3	1225
	11th to 20th	Night	17% 39% 13% 23% 7% 1	1218
	21st to end	Night	11% 39% 9% 22% 14% 4	1471
August	1st to 10th	Night	18% 39% 14% 20% 8% 1	1430
	11th to 20th	Night	13% 37% 17% 19% 9% 5%	1602
	21st to end	Night	23% 39% 13% 18% 7% 1	1854
September	1st to 10th	Night	16% 39% 12% 20% 11% 3	1800
	11th to 20th	Night	26% 39% 9% 12% 11% 2	1800
	21st to end	Night	30% 40% 10% 12% 6% 2	2059
October	1st to 10th	Night	32% 39% 9% 13% 7%	2160
	11th to 20th	Night	36% 38% 11% 11% 4 1	2160
	21st to end	Night	39% 39% 8% 8% 6%	2509
November	1st to 10th	Night	44% 42% 5% 6% 3 1	2590
	11th to 20th	Night	44% 42% 7% 5% 3	2660
	21st to end	Night	43% 42% 7% 6% 2	2660
December	1st to 10th	Night	40% 42% 7% 7% 3	2660
	11th to 20th	Night	53% 35% 6% 4 2	3487
	21st to end	Night	57% 28% 6% 6% 2	5214

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
Month	Days in Month		Occurrence of each Forecast	Data Points
January	1st to 10th	Day	37% 11% 23% 11% 12% 6%	180
	11th to 20th	Day	41% 14% 17% 11% 12% 5%	165
	21st to end	Day	41% 9% 18% 15% 13% 4	190
February	1st to 10th	Day	41% 10% 20% 17% 11% 1	340
	11th to 20th	Day	36% 9% 23% 19% 13% 1	335
	21st to end	Day	31% 14% 21% 21% 12% 2	294
March	1st to 10th	Day	32% 8% 25% 20% 12% 3	420
	11th to 20th	Day	30% 11% 18% 20% 16% 5%	420
	21st to end	Day	32% 8% 23% 22% 13% 2	462
April	1st to 10th	Day	29% 10% 20% 23% 16% 2	420
	11th to 20th	Day	23% 7% 25% 25% 15% 5%	412
	21st to end	Day	23% 7% 22% 30% 15% 3	420
May	1st to 10th	Day	13% 7% 21% 37% 19% 3	423
	11th to 20th	Day	20% 4 15% 29% 27% 6%	448
	21st to end	Day	16% 5% 23% 30% 21% 6%	497
June	1st to 10th	Day	20% 5% 21% 31% 20% 3	630
	11th to 20th	Day	18% 6% 23% 35% 15% 3	630
	21st to end	Day	13% 3 17% 33% 29% 5%	630
July	1st to 10th	Day	13% 3 15% 34% 30% 6%	621
	11th to 20th	Day	7% 4 16% 35% 31% 7%	618
	21st to end	Day	6% 1 12% 30% 39% 12%	505
August	1st to 10th	Day	8% 3 11% 28% 36% 14%	447
	11th to 20th	Day	5% 3 9% 35% 37% 12%	437
	21st to end	Day	12% 3 17% 31% 27% 10%	495
September	1st to 10th	Day	12% 4 20% 33% 25% 6%	450
	11th to 20th	Day	17% 4 18% 26% 27% 7%	450
	21st to end	Day	23% 8% 15% 26% 22% 7%	450
October	1st to 10th	Day	24% 7% 18% 22% 20% 10%	450
	11th to 20th	Day	34% 5% 16% 20% 18% 7%	450
	21st to end	Day	31% 16% 17% 18% 13% 6%	367
November	1st to 10th	Day	34% 13% 23% 16% 13% 2	180
	11th to 20th	Day	37% 9% 17% 13% 14% 10%	180
	21st to end	Day	35% 11% 20% 15% 11% 8%	180
December	1st to 10th	Day	40% 13% 16% 11% 12% 8%	180
	11th to 20th	Day	41% 16% 14% 17% 11% 1	180
	21st to end	Day	41% 12% 20% 19% 7% 2	198
January	1st to 10th	Night	44% 13% 16% 15% 10% 2	850
	11th to 20th	Night	42% 9% 14% 17% 17% 2	803
	21st to end	Night	40% 6% 15% 23% 14% 3	792
February	1st to 10th	Night	39% 10% 19% 22% 8% 2	720
	11th to 20th	Night	35% 10% 18% 25% 12% 1	704
	21st to end	Night	34% 10% 20% 22% 11% 3	592
March	1st to 10th	Night	32% 8% 21% 20% 16% 2	720
	11th to 20th	Night	35% 10% 19% 20% 14% 3	720
	21st to end	Night	35% 7% 18% 24% 13% 3	792
April	1st to 10th	Night	32% 5% 18% 26% 15% 4	720
	11th to 20th	Night	26% 7% 18% 27% 18% 4	641
	21st to end	Night	28% 6% 16% 29% 16% 4	478
May	1st to 10th	Night	18% 5% 15% 28% 30% 4	360
	11th to 20th	Night	17% 5% 9% 28% 35% 6%	354
	21st to end	Night	17% 3 12% 31% 31% 7%	389
June	1st to 10th	Night	19% 4 17% 30% 26% 4	360
	11th to 20th	Night	18% 7% 18% 31% 22% 4	360
	21st to end	Night	13% 2 13% 31% 33% 7%	360
July	1st to 10th	Night	10% 3 10% 30% 43% 5%	350
	11th to 20th	Night	7% 5% 12% 32% 38% 7%	348
	21st to end	Night	5% 2 6% 30% 47% 10%	394
August	1st to 10th	Night	8% 2 9% 23% 42% 16%	364
	11th to 20th	Night	7% 1 6% 25% 46% 15%	534
	21st to end	Night	9% 3 11% 26% 42% 10%	666
September	1st to 10th	Night	10% 2 10% 35% 35% 9%	720
	11th to 20th	Night	18% 4 13% 19% 33% 13%	720
	21st to end	Night	21% 4 14% 25% 30% 6%	720
October	1st to 10th	Night	22% 5% 13% 26% 25% 9%	720
	11th to 20th	Night	31% 6% 15% 20% 20% 7%	720
	21st to end	Night	35% 8% 17% 24% 13% 4	792
November	1st to 10th	Night	39% 10% 17% 22% 11% 1	740
	11th to 20th	Night	39% 9% 20% 17% 12% 3	760
	21st to end	Night	39% 9% 15% 20% 12% 4	760
December	1st to 10th	Night	35% 7% 18% 24% 14% 3	760
	11th to 20th	Night	45% 12% 18% 19% 6% 1	836
	21st to end	Night	44% 11% 21% 18% 5%	935

Page generated at 2024-01-10 16:35:22. Version ac07

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