Campbell River
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Campbell River clear sky chart from 2005-11-06 to 2024-04-10.

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	19% 10% 3 6% 6% 3 5% 5% 5% 6% 32%	82556
	Night	23% 12% 3 6% 5% 3 4 4 4 5% 29%	86242
Transparency	Day	53% 8% 15% 17% 6% 1	82257
	Night	59% 7% 13% 14% 5% 1	86121
Seeing	Day	26% 10% 19% 22% 17% 5%	14891
	Night	32% 9% 15% 25% 17% 3	23058

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	30% 21% 6% 7% 5% 3 4 3 3 3 14%	2219
	11th to 20th	Day	24% 16% 3 6% 5% 2 3 4 5% 6% 24%	2199
	21st to end	Day	46% 18% 3 6% 4 2 3 3 3 3 9%	2611
February	1st to 10th	Day	27% 14% 3 6% 6% 4 5% 5% 5% 5% 19%	1710
	11th to 20th	Day	22% 14% 3 8% 5% 4 4 3 4 5% 27%	1665
	21st to end	Day	20% 13% 5% 7% 6% 4 5% 5% 6% 7% 22%	1413
March	1st to 10th	Day	15% 18% 4 8% 6% 3 6% 6% 6% 7% 22%	3276
	11th to 20th	Day	17% 10% 4 8% 7% 4 6% 5% 6% 6% 29%	3490
	21st to end	Day	19% 11% 4 8% 7% 4 6% 5% 5% 6% 26%	3825
April	1st to 10th	Day	21% 12% 4 8% 6% 3 5% 6% 6% 7% 22%	2286
	11th to 20th	Day	20% 10% 5% 7% 7% 4 5% 5% 7% 6% 26%	2308
	21st to end	Day	19% 12% 5% 8% 6% 3 4 4 4 7% 28%	2340
May	1st to 10th	Day	15% 7% 3 6% 6% 3 5% 4 7% 7% 36%	2502
	11th to 20th	Day	14% 8% 3 7% 7% 3 5% 6% 7% 7% 33%	2511
	21st to end	Day	16% 7% 4 6% 6% 4 4 5% 6% 8% 33%	2917
June	1st to 10th	Day	18% 9% 4 7% 6% 4 5% 5% 6% 8% 29%	2700
	11th to 20th	Day	13% 8% 3 8% 7% 4 7% 7% 7% 8% 28%	2700
	21st to end	Day	14% 6% 3 6% 6% 3 6% 5% 6% 7% 38%	2700
July	1st to 10th	Day	12% 5% 3 5% 5% 3 5% 4 5% 7% 45%	2700
	11th to 20th	Day	9% 5% 2 4 4 3 4 6% 6% 7% 51%	2700
	21st to end	Day	6% 3 2 3 4 3 4 5% 6% 7% 57%	2938
August	1st to 10th	Day	8% 3 1 3 4 3 4 4 5% 7% 57%	2418
	11th to 20th	Day	6% 3 2 3 4 2 4 5% 5% 8% 59%	2298
	21st to end	Day	10% 5% 3 5% 5% 3 5% 5% 6% 8% 45%	2574
September	1st to 10th	Day	9% 4 2 5% 5% 3 5% 5% 5% 7% 50%	2192
	11th to 20th	Day	18% 7% 3 6% 4 3 4 4 4 5% 43%	2052
	21st to end	Day	18% 7% 3 6% 5% 3 5% 4 5% 6% 37%	1967
October	1st to 10th	Day	21% 9% 3 6% 5% 3 4 4 4 6% 35%	1800
	11th to 20th	Day	24% 11% 4 7% 5% 3 4 5% 5% 6% 27%	1800
	21st to end	Day	28% 11% 4 6% 5% 3 4 4 4 5% 26%	1788
November	1st to 10th	Day	32% 12% 4 7% 6% 4 5% 5% 5% 5% 17%	1488
	11th to 20th	Day	27% 13% 4 6% 6% 3 5% 5% 4 5% 23%	1520
	21st to end	Day	27% 14% 5% 7% 6% 3 4 4 4 5% 21%	1492
December	1st to 10th	Day	23% 14% 5% 7% 6% 3 3 4 4 5% 26%	1330
	11th to 20th	Day	32% 17% 5% 8% 6% 3 4 3 4 4 15%	1685
	21st to end	Day	33% 19% 5% 9% 5% 3 3 3 3 4 12%	2442
January	1st to 10th	Night	30% 18% 4 7% 6% 3 5% 4 4 4 15%	4726
	11th to 20th	Night	26% 14% 4 8% 7% 3 3 4 4 5% 22%	4699
	21st to end	Night	44% 16% 3 5% 4 2 3 3 3 4 12%	5046
February	1st to 10th	Night	25% 16% 4 7% 5% 4 5% 4 4 5% 21%	2470
	11th to 20th	Night	22% 12% 3 6% 4 2 4 4 5% 6% 31%	2402
	21st to end	Night	21% 15% 5% 7% 5% 4 5% 4 4 5% 26%	2041
March	1st to 10th	Night	19% 15% 3 7% 6% 4 5% 5% 5% 7% 24%	3591
	11th to 20th	Night	12% 9% 3 8% 7% 5% 6% 6% 6% 6% 34%	3489
	21st to end	Night	23% 13% 4 7% 7% 4 5% 4 4 4 26%	3828
April	1st to 10th	Night	19% 12% 4 8% 6% 4 5% 3 6% 7% 27%	1880
	11th to 20th	Night	19% 11% 4 5% 6% 4 5% 5% 6% 7% 28%	1601
	21st to end	Night	18% 11% 4 7% 5% 4 4 4 5% 7% 31%	1620
May	1st to 10th	Night	15% 6% 3 6% 5% 4 5% 5% 4 7% 40%	1458
	11th to 20th	Night	14% 9% 3 8% 6% 4 5% 7% 6% 8% 31%	1381
	21st to end	Night	15% 11% 5% 7% 5% 3 4 5% 6% 6% 33%	1358
June	1st to 10th	Night	16% 9% 4 6% 5% 4 5% 5% 5% 6% 35%	1260
	11th to 20th	Night	14% 8% 4 7% 8% 5% 6% 6% 6% 6% 30%	1260
	21st to end	Night	13% 6% 3 8% 5% 3 5% 4 6% 7% 39%	1260
July	1st to 10th	Night	11% 5% 3 6% 4 3 4 4 5% 7% 49%	1260
	11th to 20th	Night	8% 3 2 4 5% 2 5% 5% 6% 7% 53%	1260
	21st to end	Night	7% 3 2 4 4 2 4 3 4 5% 62%	1379
August	1st to 10th	Night	9% 4 2 4 5% 2 3 3 4 7% 56%	1518
	11th to 20th	Night	6% 4 2 3 4 2 4 4 5% 8% 58%	1602
	21st to end	Night	10% 5% 2 5% 5% 3 4 6% 5% 9% 46%	1782
September	1st to 10th	Night	10% 5% 3 5% 5% 2 4 3 5% 6% 52%	1767
	11th to 20th	Night	19% 7% 3 6% 5% 2 3 3 4 5% 43%	1907
	21st to end	Night	19% 8% 3 5% 4 2 4 4 5% 5% 41%	1993
October	1st to 10th	Night	18% 9% 2 6% 4 3 4 4 4 6% 41%	2160
	11th to 20th	Night	24% 10% 3 6% 5% 3 4 4 4 6% 30%	2160
	21st to end	Night	28% 11% 3 6% 5% 3 3 3 4 5% 28%	2567
November	1st to 10th	Night	30% 15% 3 6% 6% 3 5% 4 5% 5% 18%	2590
	11th to 20th	Night	24% 13% 5% 7% 6% 3 5% 5% 5% 5% 21%	2660
	21st to end	Night	26% 14% 4 7% 6% 3 5% 4 4 4 22%	2683
December	1st to 10th	Night	23% 14% 5% 8% 6% 3 4 4 4 5% 24%	2850
	11th to 20th	Night	35% 17% 5% 7% 5% 2 4 3 4 4 14%	3520
	21st to end	Night	36% 18% 4 6% 5% 3 3 3 3 3 15%	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	75% 7% 6% 9% 3	2219
	11th to 20th	Day	60% 7% 15% 10% 7% 1	2220
	21st to end	Day	84% 5% 5% 4 1	2611
February	1st to 10th	Day	68% 9% 7% 9% 4 3	1710
	11th to 20th	Day	63% 6% 11% 14% 4 2	1674
	21st to end	Day	60% 8% 13% 11% 7% 2	1413
March	1st to 10th	Day	61% 8% 11% 13% 5%	3276
	11th to 20th	Day	56% 8% 11% 21% 3	3490
	21st to end	Day	58% 9% 17% 12% 4	3825
April	1st to 10th	Day	61% 8% 14% 12% 5%	2286
	11th to 20th	Day	55% 8% 13% 16% 8% 1	2308
	21st to end	Day	56% 8% 13% 14% 8% 1	2340
May	1st to 10th	Day	45% 9% 20% 21% 6%	2502
	11th to 20th	Day	47% 9% 19% 19% 6% 1	2514
	21st to end	Day	48% 7% 19% 20% 6%	2918
June	1st to 10th	Day	51% 10% 17% 16% 5% 2	2700
	11th to 20th	Day	49% 10% 19% 16% 6%	2700
	21st to end	Day	43% 9% 20% 21% 7% 1	2700
July	1st to 10th	Day	36% 9% 22% 21% 10% 1	2626
	11th to 20th	Day	30% 10% 24% 29% 7%	2619
	21st to end	Day	23% 9% 24% 30% 12% 2	2775
August	1st to 10th	Day	25% 8% 24% 30% 11% 1	2400
	11th to 20th	Day	24% 10% 24% 27% 14% 1	2298
	21st to end	Day	35% 9% 25% 24% 6%	2574
September	1st to 10th	Day	34% 9% 20% 26% 10% 1	2192
	11th to 20th	Day	45% 8% 13% 20% 13% 1	2052
	21st to end	Day	49% 8% 15% 18% 9% 1	1967
October	1st to 10th	Day	52% 8% 13% 18% 9% 1	1800
	11th to 20th	Day	61% 8% 14% 14% 3	1800
	21st to end	Day	63% 7% 12% 12% 7%	1788
November	1st to 10th	Day	71% 7% 9% 7% 5% 1	1488
	11th to 20th	Day	67% 9% 9% 10% 4 1	1520
	21st to end	Day	68% 8% 9% 10% 5% 1	1492
December	1st to 10th	Day	63% 7% 12% 11% 5% 1	1330
	11th to 20th	Day	77% 6% 7% 6% 4 1	1688
	21st to end	Day	78% 6% 6% 7% 3 1	2442
January	1st to 10th	Night	75% 8% 7% 7% 3 1	4726
	11th to 20th	Night	62% 8% 12% 8% 6% 3	4740
	21st to end	Night	81% 6% 5% 6% 2	5046
February	1st to 10th	Night	69% 6% 8% 9% 7% 1	2470
	11th to 20th	Night	57% 8% 12% 15% 6% 1	2404
	21st to end	Night	61% 6% 12% 14% 5% 2	2041
March	1st to 10th	Night	61% 8% 12% 14% 5%	3591
	11th to 20th	Night	53% 9% 12% 22% 3	3490
	21st to end	Night	64% 8% 12% 12% 5% 1	3828
April	1st to 10th	Night	59% 8% 14% 15% 4	1880
	11th to 20th	Night	56% 8% 11% 18% 7%	1601
	21st to end	Night	55% 7% 11% 18% 8%	1620
May	1st to 10th	Night	45% 7% 18% 22% 7%	1458
	11th to 20th	Night	51% 8% 20% 16% 5% 1	1381
	21st to end	Night	50% 7% 21% 17% 5%	1358
June	1st to 10th	Night	51% 8% 20% 15% 5% 1	1260
	11th to 20th	Night	51% 10% 18% 17% 4	1260
	21st to end	Night	45% 7% 20% 20% 7% 1	1260
July	1st to 10th	Night	37% 7% 20% 26% 9% 1	1225
	11th to 20th	Night	31% 10% 27% 24% 8%	1218
	21st to end	Night	24% 7% 23% 34% 10% 1	1302
August	1st to 10th	Night	28% 8% 21% 32% 10% 1	1511
	11th to 20th	Night	25% 8% 26% 26% 12% 1	1602
	21st to end	Night	36% 9% 24% 26% 5%	1782
September	1st to 10th	Night	33% 7% 20% 29% 9% 1	1767
	11th to 20th	Night	45% 7% 13% 20% 14% 2	1907
	21st to end	Night	48% 7% 19% 17% 9% 1	1993
October	1st to 10th	Night	47% 6% 17% 20% 9%	2160
	11th to 20th	Night	59% 6% 16% 16% 3	2160
	21st to end	Night	61% 6% 12% 16% 6%	2567
November	1st to 10th	Night	70% 8% 8% 9% 4 1	2590
	11th to 20th	Night	68% 7% 10% 9% 4 1	2660
	21st to end	Night	68% 7% 7% 11% 5% 1	2683
December	1st to 10th	Night	65% 7% 11% 11% 5% 1	2850
	11th to 20th	Night	78% 5% 7% 7% 3 1	3516
	21st to end	Night	76% 7% 7% 7% 3 1	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	49% 6% 16% 19% 5% 5%	180
	11th to 20th	Day	47% 11% 12% 16% 13% 1	180
	21st to end	Day	48% 11% 10% 15% 13% 3	293
February	1st to 10th	Day	41% 15% 19% 14% 11% 1	370
	11th to 20th	Day	35% 13% 17% 23% 10% 3	365
	21st to end	Day	34% 11% 25% 19% 9% 2	307
March	1st to 10th	Day	31% 13% 18% 18% 15% 5%	424
	11th to 20th	Day	33% 15% 14% 18% 16% 4	460
	21st to end	Day	34% 15% 16% 18% 13% 4	506
April	1st to 10th	Day	32% 16% 23% 17% 8% 4	457
	11th to 20th	Day	30% 9% 21% 19% 14% 7%	412
	21st to end	Day	29% 16% 20% 19% 12% 5%	420
May	1st to 10th	Day	19% 10% 26% 25% 17% 4	423
	11th to 20th	Day	20% 5% 21% 27% 20% 7%	481
	21st to end	Day	17% 10% 27% 25% 18% 4	680
June	1st to 10th	Day	22% 14% 23% 23% 16% 2	630
	11th to 20th	Day	17% 14% 26% 25% 15% 3	630
	21st to end	Day	17% 8% 21% 29% 18% 5%	630
July	1st to 10th	Day	15% 8% 21% 28% 21% 7%	621
	11th to 20th	Day	11% 9% 22% 29% 24% 4	618
	21st to end	Day	8% 5% 18% 31% 30% 8%	684
August	1st to 10th	Day	10% 5% 16% 28% 28% 14%	461
	11th to 20th	Day	8% 4 18% 36% 29% 5%	437
	21st to end	Day	13% 9% 19% 31% 21% 6%	495
September	1st to 10th	Day	17% 8% 20% 31% 16% 8%	450
	11th to 20th	Day	29% 8% 14% 19% 20% 10%	450
	21st to end	Day	27% 12% 17% 21% 19% 5%	450
October	1st to 10th	Day	31% 9% 16% 16% 19% 9%	450
	11th to 20th	Day	38% 8% 16% 15% 16% 6%	450
	21st to end	Day	40% 10% 17% 15% 11% 6%	379
November	1st to 10th	Day	41% 17% 18% 11% 12% 2	180
	11th to 20th	Day	39% 9% 13% 15% 13% 11%	180
	21st to end	Day	51% 9% 13% 12% 8% 7%	180
December	1st to 10th	Day	43% 6% 14% 14% 12% 10%	180
	11th to 20th	Day	41% 11% 16% 14% 12% 5%	180
	21st to end	Day	47% 10% 16% 17% 10% 2	198
January	1st to 10th	Night	46% 10% 14% 17% 9% 4	850
	11th to 20th	Night	44% 9% 9% 20% 16% 2	850
	21st to end	Night	43% 8% 10% 22% 13% 4	929
February	1st to 10th	Night	41% 9% 16% 21% 12% 1	760
	11th to 20th	Night	32% 9% 14% 27% 16% 1	744
	21st to end	Night	33% 13% 15% 24% 12% 3	628
March	1st to 10th	Night	33% 13% 16% 18% 16% 4	760
	11th to 20th	Night	30% 14% 14% 22% 18% 2	760
	21st to end	Night	33% 12% 17% 20% 15% 3	836
April	1st to 10th	Night	30% 11% 14% 26% 15% 3	724
	11th to 20th	Night	27% 11% 15% 31% 16% 1	533
	21st to end	Night	27% 12% 17% 26% 14% 3	540
May	1st to 10th	Night	20% 7% 21% 28% 18% 6%	378
	11th to 20th	Night	21% 6% 21% 28% 20% 4	354
	21st to end	Night	22% 9% 24% 26% 18% 1	389
June	1st to 10th	Night	23% 9% 23% 28% 16% 1	360
	11th to 20th	Night	18% 8% 26% 29% 18% 1	360
	21st to end	Night	17% 7% 24% 30% 19% 3	360
July	1st to 10th	Night	16% 7% 22% 27% 25% 4	350
	11th to 20th	Night	11% 8% 25% 34% 19% 3	348
	21st to end	Night	7% 5% 20% 43% 22% 3	394
August	1st to 10th	Night	10% 3 17% 38% 27% 6%	458
	11th to 20th	Night	11% 4 17% 35% 31% 3	534
	21st to end	Night	16% 5% 20% 31% 25% 3	594
September	1st to 10th	Night	15% 6% 15% 33% 27% 4	687
	11th to 20th	Night	23% 7% 11% 23% 26% 11%	720
	21st to end	Night	29% 7% 14% 24% 21% 5%	720
October	1st to 10th	Night	27% 6% 13% 27% 23% 4	720
	11th to 20th	Night	37% 6% 11% 23% 18% 5%	720
	21st to end	Night	42% 9% 14% 19% 14% 3	792
November	1st to 10th	Night	44% 9% 11% 24% 11% 1	740
	11th to 20th	Night	40% 9% 14% 23% 12% 3	760
	21st to end	Night	42% 9% 13% 21% 12% 4	771
December	1st to 10th	Night	37% 9% 13% 21% 16% 4	850
	11th to 20th	Night	46% 9% 12% 18% 12% 3	850
	21st to end	Night	45% 11% 14% 21% 8%	935

Page generated at 2024-04-07 06:28:09. Version ac07

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