Wild Rose Ridge Observatory
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Wild Rose Ridge Observatory clear sky chart from 2005-11-06 to 2025-03-12.

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 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	5% 7% 2 6% 4 4 5% 4 6% 7% 50%	112749
	Night	5% 9% 3 7% 4 4 4 4 6% 7% 46%	114928
Transparency	Day	33% 8% 13% 23% 16% 6%	112518
	Night	36% 8% 15% 24% 13% 4	114805
Seeing	Day	11% 16% 31% 28% 11% 2	14663
	Night	10% 9% 31% 34% 15% 2	23802

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	7% 16% 5% 10% 7% 7% 6% 4 6% 7% 24%	3639
	11th to 20th	Day	6% 12% 5% 8% 4 4 4 3 6% 7% 43%	3616
	21st to end	Day	10% 13% 3 8% 6% 5% 5% 4 7% 7% 33%	4004
February	1st to 10th	Day	6% 10% 3 10% 6% 6% 5% 5% 7% 8% 33%	1760
	11th to 20th	Day	5% 11% 4 9% 5% 6% 5% 4 7% 9% 37%	1755
	21st to end	Day	5% 10% 4 10% 7% 5% 6% 6% 8% 7% 33%	1631
March	1st to 10th	Day	3 10% 3 7% 6% 5% 7% 5% 8% 9% 37%	3238
	11th to 20th	Day	4 7% 2 5% 4 4 5% 4 5% 7% 53%	3426
	21st to end	Day	9% 9% 3 7% 5% 5% 6% 5% 7% 9% 34%	4062
April	1st to 10th	Day	7% 9% 3 8% 7% 5% 7% 6% 9% 8% 33%	2280
	11th to 20th	Day	5% 7% 3 6% 7% 5% 6% 4 7% 10% 41%	2252
	21st to end	Day	5% 5% 3 6% 5% 5% 6% 4 9% 9% 44%	2517
May	1st to 10th	Day	6% 5% 2 5% 4 4 4 4 4 7% 55%	4420
	11th to 20th	Day	5% 4 1 4 4 4 3 3 5% 8% 59%	4377
	21st to end	Day	9% 8% 3 7% 6% 5% 6% 4 6% 7% 38%	4813
June	1st to 10th	Day	7% 6% 2 6% 5% 5% 6% 4 7% 8% 44%	2660
	11th to 20th	Day	4 4 2 6% 5% 4 4 4 6% 9% 51%	2660
	21st to end	Day	4 3 1 5% 4 4 4 3 5% 7% 60%	2660
July	1st to 10th	Day	1 1 1 2 1 2 2 2 3 4 80%	4420
	11th to 20th	Day	1 2 2 2 2 2 2 3 4 79%	4420
	21st to end	Day	2 2 1 2 2 2 2 1 3 4 80%	4790
August	1st to 10th	Day	1 2 1 2 2 3 3 3 5% 6% 74%	4401
	11th to 20th	Day	1 1 1 3 3 3 5% 4 5% 8% 65%	4118
	21st to end	Day	4 5% 2 4 3 3 3 3 4 5% 62%	4215
September	1st to 10th	Day	3 2 1 3 2 2 3 2 5% 7% 70%	2280
	11th to 20th	Day	3 4 2 4 3 5% 6% 4 7% 8% 54%	2280
	21st to end	Day	5% 3 2 5% 4 5% 5% 4 5% 7% 57%	2044
October	1st to 10th	Day	3 3 2 6% 4 3 3 3 5% 8% 60%	3180
	11th to 20th	Day	5% 6% 2 7% 5% 5% 6% 5% 8% 9% 44%	3161
	21st to end	Day	6% 7% 3 7% 4 5% 6% 5% 6% 8% 43%	3117
November	1st to 10th	Day	7% 11% 3 7% 5% 6% 5% 4 7% 9% 36%	1704
	11th to 20th	Day	5% 12% 3 11% 7% 6% 6% 5% 6% 7% 32%	1600
	21st to end	Day	5% 13% 4 10% 7% 5% 5% 5% 7% 9% 31%	1600
December	1st to 10th	Day	4 8% 3 9% 5% 5% 5% 4 9% 7% 39%	2620
	11th to 20th	Day	7% 17% 6% 14% 7% 7% 5% 4 5% 7% 20%	3025
	21st to end	Day	9% 18% 7% 14% 6% 6% 5% 4 5% 6% 23%	4004
January	1st to 10th	Night	7% 19% 7% 15% 6% 5% 4 4 4 5% 23%	6306
	11th to 20th	Night	7% 12% 4 7% 5% 5% 5% 4 6% 8% 39%	6282
	21st to end	Night	8% 15% 5% 12% 6% 5% 4 3 6% 7% 29%	6952
February	1st to 10th	Night	6% 13% 4 9% 6% 5% 5% 5% 7% 8% 32%	2638
	11th to 20th	Night	6% 10% 3 8% 5% 5% 5% 5% 6% 7% 40%	2532
	21st to end	Night	5% 10% 4 10% 5% 6% 5% 6% 7% 8% 35%	1998
March	1st to 10th	Night	4 10% 3 5% 4 5% 5% 6% 8% 10% 39%	3856
	11th to 20th	Night	3 6% 1 4 4 4 4 4 6% 8% 56%	3578
	21st to end	Night	7% 8% 3 7% 6% 6% 6% 5% 8% 9% 34%	3590
April	1st to 10th	Night	5% 6% 2 7% 6% 5% 5% 6% 8% 10% 40%	1900
	11th to 20th	Night	3 7% 2 6% 4 5% 5% 3 6% 7% 51%	1879
	21st to end	Night	6% 4 1 5% 4 4 4 5% 7% 9% 49%	1658
May	1st to 10th	Night	6% 4 2 4 3 3 4 3 6% 7% 58%	2540
	11th to 20th	Night	4 3 1 4 3 3 4 4 5% 7% 61%	2516
	21st to end	Night	3 3 2 4 3 4 6% 6% 9% 11% 49%	2762
June	1st to 10th	Night	5% 6% 2 5% 3 5% 4 5% 7% 8% 50%	1520
	11th to 20th	Night	3 4 2 5% 3 3 5% 5% 7% 8% 54%	1520
	21st to end	Night	2 2 1 4 3 4 3 4 6% 7% 64%	1520
July	1st to 10th	Night	1 2 1 1 2 3 3 4 82%	2540
	11th to 20th	Night	1 1 1 1 2 1 3 4 85%	2540
	21st to end	Night	1 1 1 1 1 2 2 3 4 84%	2762
August	1st to 10th	Night	1 2 1 3 2 2 2 2 4 5% 74%	2529
	11th to 20th	Night	2 1 1 3 2 2 3 3 4 7% 72%	2714
	21st to end	Night	4 2 1 3 3 3 3 3 4 6% 67%	3461
September	1st to 10th	Night	3 2 1 2 2 3 3 3 5% 7% 70%	1900
	11th to 20th	Night	3 4 1 4 3 3 3 5% 5% 8% 61%	1900
	21st to end	Night	4 3 1 4 3 3 5% 3 6% 9% 60%	2132
October	1st to 10th	Night	3 4 2 4 3 3 5% 4 6% 8% 57%	3800
	11th to 20th	Night	5% 4 2 6% 3 4 6% 5% 7% 9% 50%	3777
	21st to end	Night	7% 6% 3 8% 4 5% 5% 4 5% 7% 46%	4440
November	1st to 10th	Night	10% 9% 3 7% 5% 4 5% 5% 7% 9% 35%	2594
	11th to 20th	Night	7% 11% 3 7% 7% 5% 5% 5% 6% 7% 38%	2800
	21st to end	Night	6% 15% 4 11% 5% 5% 4 5% 5% 8% 33%	2800
December	1st to 10th	Night	5% 9% 2 9% 5% 4 4 4 8% 7% 42%	4560
	11th to 20th	Night	9% 15% 6% 15% 7% 6% 5% 5% 6% 7% 19%	5180
	21st to end	Night	11% 19% 6% 11% 5% 5% 4 3 5% 6% 24%	6952

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	57% 12% 10% 16% 5%	3639
	11th to 20th	Day	41% 8% 16% 26% 9%	3640
	21st to end	Day	48% 10% 13% 21% 8%	4004
February	1st to 10th	Day	47% 13% 17% 16% 5% 2	1760
	11th to 20th	Day	44% 12% 17% 17% 8% 1	1764
	21st to end	Day	47% 13% 17% 17% 6% 1	1631
March	1st to 10th	Day	37% 12% 15% 20% 15% 1	3238
	11th to 20th	Day	29% 8% 13% 43% 7%	3426
	21st to end	Day	42% 14% 18% 19% 7%	4062
April	1st to 10th	Day	44% 10% 18% 19% 8% 1	2280
	11th to 20th	Day	38% 10% 16% 21% 12% 2	2252
	21st to end	Day	35% 11% 15% 24% 13% 2	2517
May	1st to 10th	Day	26% 8% 13% 23% 26% 5%	4420
	11th to 20th	Day	22% 7% 16% 33% 21% 2	4380
	21st to end	Day	40% 12% 16% 26% 6%	4814
June	1st to 10th	Day	35% 8% 14% 24% 14% 4	2660
	11th to 20th	Day	28% 9% 16% 29% 16% 3	2660
	21st to end	Day	23% 5% 15% 30% 23% 4	2660
July	1st to 10th	Day	10% 3 8% 16% 27% 36%	4351
	11th to 20th	Day	12% 2 4 12% 27% 42%	4345
	21st to end	Day	11% 2 6% 23% 37% 21%	4639
August	1st to 10th	Day	13% 3 7% 24% 35% 18%	4384
	11th to 20th	Day	18% 5% 14% 37% 22% 4	4160
	21st to end	Day	25% 4 11% 26% 28% 5%	4214
September	1st to 10th	Day	16% 4 12% 29% 30% 9%	2280
	11th to 20th	Day	26% 8% 14% 24% 22% 6%	2280
	21st to end	Day	27% 6% 17% 28% 17% 5%	2044
October	1st to 10th	Day	25% 5% 12% 40% 17% 1	3180
	11th to 20th	Day	36% 8% 15% 23% 18%	3161
	21st to end	Day	39% 8% 11% 24% 14% 4	3117
November	1st to 10th	Day	46% 11% 15% 18% 9% 1	1704
	11th to 20th	Day	50% 12% 17% 14% 6% 1	1600
	21st to end	Day	49% 13% 17% 13% 7% 1	1600
December	1st to 10th	Day	40% 9% 20% 23% 8%	2620
	11th to 20th	Day	63% 10% 13% 10% 4	3028
	21st to end	Day	62% 9% 11% 14% 4	4004
January	1st to 10th	Night	61% 9% 13% 13% 4	6306
	11th to 20th	Night	43% 7% 16% 26% 9%	6320
	21st to end	Night	53% 9% 11% 19% 8%	6952
February	1st to 10th	Night	49% 11% 18% 16% 5% 1	2638
	11th to 20th	Night	43% 10% 19% 19% 8% 1	2534
	21st to end	Night	43% 13% 16% 19% 9% 1	1998
March	1st to 10th	Night	34% 11% 17% 22% 14% 3	3856
	11th to 20th	Night	24% 7% 21% 39% 8%	3579
	21st to end	Night	40% 14% 19% 23% 4	3590
April	1st to 10th	Night	35% 10% 22% 24% 8% 1	1900
	11th to 20th	Night	32% 9% 19% 22% 17% 1	1879
	21st to end	Night	29% 10% 18% 30% 13% 1	1658
May	1st to 10th	Night	24% 7% 13% 28% 25% 3	2540
	11th to 20th	Night	22% 7% 16% 35% 19% 1	2516
	21st to end	Night	22% 13% 23% 35% 6%	2762
June	1st to 10th	Night	30% 8% 16% 27% 16% 2	1520
	11th to 20th	Night	26% 6% 20% 31% 15% 1	1520
	21st to end	Night	18% 7% 16% 35% 20% 4	1520
July	1st to 10th	Night	8% 3 9% 21% 27% 31%	2500
	11th to 20th	Night	6% 3 7% 17% 30% 37%	2492
	21st to end	Night	7% 2 7% 27% 36% 21%	2674
August	1st to 10th	Night	13% 3 7% 26% 34% 17%	2521
	11th to 20th	Night	14% 4 22% 36% 18% 5%	2738
	21st to end	Night	20% 4 15% 30% 26% 5%	3461
September	1st to 10th	Night	15% 5% 15% 27% 30% 8%	1900
	11th to 20th	Night	22% 7% 13% 28% 23% 8%	1900
	21st to end	Night	21% 6% 17% 34% 16% 6%	2132
October	1st to 10th	Night	26% 5% 12% 42% 14% 1	3800
	11th to 20th	Night	32% 7% 16% 29% 16% 1	3777
	21st to end	Night	39% 7% 12% 28% 12% 3	4440
November	1st to 10th	Night	46% 9% 17% 19% 8% 1	2594
	11th to 20th	Night	46% 12% 18% 17% 6% 1	2800
	21st to end	Night	49% 10% 16% 17% 7% 1	2800
December	1st to 10th	Night	39% 8% 18% 28% 7%	4560
	11th to 20th	Night	64% 11% 12% 9% 4	5176
	21st to end	Night	61% 8% 13% 13% 5%	6952

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	18% 13% 27% 29% 11% 3	200
	11th to 20th	Day	18% 9% 31% 26% 14% 4	200
	21st to end	Day	15% 7% 32% 33% 10% 4	220
February	1st to 10th	Day	11% 20% 39% 26% 4 1	360
	11th to 20th	Day	14% 21% 36% 22% 6% 1	395
	21st to end	Day	10% 21% 37% 24% 6% 1	405
March	1st to 10th	Day	12% 23% 37% 21% 7% 1	500
	11th to 20th	Day	14% 20% 31% 23% 12%	465
	21st to end	Day	17% 23% 33% 22% 4	506
April	1st to 10th	Day	18% 22% 31% 20% 6% 2	460
	11th to 20th	Day	12% 29% 31% 18% 7% 2	452
	21st to end	Day	12% 24% 33% 21% 8% 2	460
May	1st to 10th	Day	11% 16% 39% 26% 7% 1	463
	11th to 20th	Day	18% 13% 28% 27% 11% 2	488
	21st to end	Day	12% 16% 29% 27% 13% 3	529
June	1st to 10th	Day	10% 20% 32% 25% 11% 2	490
	11th to 20th	Day	12% 22% 35% 22% 8% 1	490
	21st to end	Day	6% 16% 29% 31% 15% 3	490
July	1st to 10th	Day	5% 11% 31% 40% 12% 1	486
	11th to 20th	Day	4 13% 31% 36% 12% 4	484
	21st to end	Day	4 9% 30% 38% 16% 3	531
August	1st to 10th	Day	4 10% 28% 36% 18% 3	487
	11th to 20th	Day	3 8% 24% 40% 19% 6%	477
	21st to end	Day	7% 13% 30% 30% 15% 4	539
September	1st to 10th	Day	5% 11% 34% 30% 16% 4	490
	11th to 20th	Day	8% 13% 32% 33% 13% 2	490
	21st to end	Day	11% 17% 30% 28% 13% 2	490
October	1st to 10th	Day	14% 12% 30% 27% 16% 2	490
	11th to 20th	Day	13% 14% 30% 27% 13% 3	490
	21st to end	Day	14% 19% 30% 25% 10% 3	346
November	1st to 10th	Day	16% 15% 30% 28% 10% 1	270
	11th to 20th	Day	18% 18% 28% 19% 13% 5%	200
	21st to end	Day	11% 10% 28% 33% 14% 5%	200
December	1st to 10th	Day	11% 13% 24% 28% 18% 8%	200
	11th to 20th	Day	10% 11% 32% 37% 11% 1	200
	21st to end	Day	9% 10% 34% 34% 11% 2	220
January	1st to 10th	Night	18% 12% 31% 25% 14% 1	800
	11th to 20th	Night	16% 9% 29% 31% 13% 1	800
	21st to end	Night	15% 7% 28% 34% 15% 2	880
February	1st to 10th	Night	14% 9% 34% 31% 11% 1	800
	11th to 20th	Night	12% 12% 29% 34% 13% 1	784
	21st to end	Night	10% 13% 31% 29% 15% 1	660
March	1st to 10th	Night	13% 8% 33% 35% 10% 1	800
	11th to 20th	Night	7% 11% 33% 32% 15% 1	766
	21st to end	Night	10% 13% 36% 33% 7% 1	836
April	1st to 10th	Night	9% 12% 33% 32% 13% 1	760
	11th to 20th	Night	7% 15% 35% 32% 10% 2	751
	21st to end	Night	6% 12% 41% 30% 11% 1	518
May	1st to 10th	Night	5% 11% 33% 35% 14% 2	380
	11th to 20th	Night	9% 6% 24% 40% 19% 1	374
	21st to end	Night	7% 6% 28% 39% 19% 1	411
June	1st to 10th	Night	8% 7% 34% 35% 15% 1	380
	11th to 20th	Night	7% 12% 36% 34% 11%	380
	21st to end	Night	3 9% 34% 35% 19%	380
July	1st to 10th	Night	4 4 31% 44% 16%	370
	11th to 20th	Night	6% 39% 40% 14% 1	368
	21st to end	Night	1 5% 28% 43% 22%	416
August	1st to 10th	Night	2 6% 22% 42% 26% 2	378
	11th to 20th	Night	2 4 22% 40% 28% 3	502
	21st to end	Night	5% 7% 26% 38% 22% 2	812
September	1st to 10th	Night	4 5% 29% 37% 23% 3	760
	11th to 20th	Night	6% 6% 23% 32% 28% 6%	760
	21st to end	Night	6% 7% 27% 36% 20% 4	760
October	1st to 10th	Night	9% 8% 25% 36% 21% 1	760
	11th to 20th	Night	8% 8% 28% 33% 20% 3	760
	21st to end	Night	13% 11% 31% 31% 12% 3	836
November	1st to 10th	Night	15% 9% 31% 36% 9%	780
	11th to 20th	Night	15% 11% 31% 29% 12% 2	800
	21st to end	Night	15% 8% 30% 30% 15% 2	800
December	1st to 10th	Night	12% 8% 32% 32% 14% 2	800
	11th to 20th	Night	15% 7% 33% 35% 10%	800
	21st to end	Night	16% 9% 33% 34% 7% 1	880

Page generated at 2025-03-09 05:08:46. Version ac07

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