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 2005-11-05 to 2024-10-14.

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%	101384
	Night	6% 9% 3 7% 4 4 4 4 6% 7% 47%	97268
Transparency	Day	32% 8% 13% 23% 16% 7%	101153
	Night	36% 9% 15% 23% 13% 4	97145
Seeing	Day	11% 16% 32% 28% 11% 2	14277
	Night	10% 9% 30% 34% 15% 2	23206

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% 6% 11% 6% 6% 6% 4 6% 7% 24%	2539
	11th to 20th	Day	8% 17% 7% 11% 5% 5% 4 3 3 6% 31%	2516
	21st to end	Day	15% 18% 4 10% 7% 6% 5% 4 6% 5% 20%	2794
February	1st to 10th	Day	6% 10% 3 9% 6% 6% 5% 5% 7% 8% 33%	1672
	11th to 20th	Day	5% 10% 4 9% 5% 6% 4 4 7% 9% 37%	1665
	21st to end	Day	5% 10% 4 9% 7% 5% 6% 6% 7% 7% 33%	1551
March	1st to 10th	Day	4 10% 3 7% 5% 6% 7% 5% 8% 9% 38%	3138
	11th to 20th	Day	4 7% 2 5% 4 4 5% 4 5% 7% 53%	3415
	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	6% 4 2 5% 5% 4 4 4 5% 7% 54%	1900
	11th to 20th	Day	6% 6% 2 5% 5% 4 5% 4 7% 9% 47%	1831
	21st to end	Day	9% 7% 3 6% 4 4 6% 5% 6% 9% 41%	1798
November	1st to 10th	Day	7% 11% 3 7% 5% 6% 5% 4 7% 9% 35%	1617
	11th to 20th	Day	5% 11% 3 10% 7% 7% 6% 5% 6% 7% 32%	1520
	21st to end	Day	5% 13% 4 10% 7% 5% 5% 5% 7% 8% 32%	1520
December	1st to 10th	Day	7% 13% 4 11% 6% 5% 5% 5% 7% 6% 32%	1520
	11th to 20th	Day	7% 14% 5% 14% 8% 7% 5% 5% 5% 7% 23%	1925
	21st to end	Day	8% 18% 7% 14% 6% 6% 5% 4 4 5% 24%	2794
January	1st to 10th	Night	6% 20% 6% 13% 7% 6% 4 4 5% 5% 24%	4406
	11th to 20th	Night	9% 16% 6% 9% 5% 4 4 3 5% 7% 29%	4382
	21st to end	Night	11% 20% 6% 15% 7% 5% 4 4 4 6% 17%	4862
February	1st to 10th	Night	7% 13% 4 9% 6% 5% 5% 5% 7% 8% 32%	2507
	11th to 20th	Night	6% 10% 3 8% 5% 5% 5% 5% 6% 7% 41%	2402
	21st to end	Night	5% 10% 4 10% 5% 6% 5% 6% 7% 9% 35%	1902
March	1st to 10th	Night	4 10% 3 6% 4 5% 5% 6% 8% 10% 39%	3736
	11th to 20th	Night	3 6% 1 4 4 4 4 3 6% 9% 57%	3561
	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	5% 5% 2 6% 4 3 5% 4 6% 7% 53%	2280
	11th to 20th	Night	5% 4 2 5% 3 4 6% 5% 7% 8% 51%	2207
	21st to end	Night	10% 7% 2 6% 3 5% 5% 3 6% 8% 45%	2557
November	1st to 10th	Night	10% 9% 3 7% 5% 4 5% 5% 7% 9% 36%	2461
	11th to 20th	Night	6% 11% 3 7% 7% 5% 5% 5% 6% 7% 38%	2660
	21st to end	Night	5% 15% 4 10% 5% 5% 4 5% 5% 7% 34%	2660
December	1st to 10th	Night	8% 15% 4 11% 6% 5% 5% 4 6% 7% 31%	2660
	11th to 20th	Night	8% 14% 5% 14% 7% 6% 5% 5% 6% 7% 23%	3280
	21st to end	Night	10% 19% 7% 12% 5% 5% 4 3 5% 5% 24%	4862

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% 15% 11% 12% 5%	2539
	11th to 20th	Day	55% 10% 14% 17% 3	2540
	21st to end	Day	62% 13% 13% 9% 3	2794
February	1st to 10th	Day	47% 13% 18% 17% 4 1	1672
	11th to 20th	Day	43% 13% 17% 18% 8% 1	1674
	21st to end	Day	46% 13% 17% 17% 6% 1	1551
March	1st to 10th	Day	37% 12% 15% 20% 14% 1	3138
	11th to 20th	Day	29% 8% 13% 43% 7%	3415
	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	29% 7% 15% 33% 14% 2	1900
	11th to 20th	Day	32% 10% 17% 27% 13%	1831
	21st to end	Day	40% 9% 14% 24% 13%	1798
November	1st to 10th	Day	46% 11% 15% 18% 9% 1	1617
	11th to 20th	Day	49% 12% 18% 14% 5% 1	1520
	21st to end	Day	48% 13% 17% 14% 7% 1	1520
December	1st to 10th	Day	50% 12% 15% 16% 7%	1520
	11th to 20th	Day	58% 14% 16% 9% 3	1928
	21st to end	Day	62% 9% 11% 12% 5%	2794
January	1st to 10th	Night	58% 11% 15% 10% 5%	4406
	11th to 20th	Night	55% 8% 14% 18% 6%	4420
	21st to end	Night	67% 11% 11% 9% 2	4862
February	1st to 10th	Night	49% 12% 19% 16% 4 1	2507
	11th to 20th	Night	43% 10% 19% 19% 8% 1	2404
	21st to end	Night	43% 14% 15% 19% 9%	1902
March	1st to 10th	Night	34% 11% 17% 22% 14% 3	3736
	11th to 20th	Night	24% 7% 21% 40% 8%	3562
	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	30% 6% 13% 32% 17% 1	2280
	11th to 20th	Night	30% 9% 17% 29% 15% 1	2207
	21st to end	Night	37% 9% 13% 29% 11% 1	2557
November	1st to 10th	Night	45% 10% 17% 20% 8% 1	2461
	11th to 20th	Night	45% 12% 18% 18% 5% 2	2660
	21st to end	Night	49% 10% 16% 17% 8% 1	2660
December	1st to 10th	Night	54% 9% 15% 17% 4	2660
	11th to 20th	Night	59% 15% 15% 8% 3	3276
	21st to end	Night	61% 9% 13% 12% 5%	4862

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% 27% 12% 3	180
	11th to 20th	Day	18% 10% 29% 26% 13% 4	180
	21st to end	Day	16% 8% 34% 30% 9% 4	198
February	1st to 10th	Day	11% 21% 38% 25% 4 1	332
	11th to 20th	Day	13% 22% 36% 22% 6% 1	365
	21st to end	Day	9% 22% 37% 24% 7% 1	373
March	1st to 10th	Day	12% 24% 36% 22% 7% 1	460
	11th to 20th	Day	14% 19% 31% 23% 13%	460
	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	12% 14% 31% 26% 14% 3	463
	21st to end	Day	14% 18% 29% 26% 10% 3	313
November	1st to 10th	Day	14% 16% 32% 29% 9% 1	243
	11th to 20th	Day	16% 19% 28% 17% 14% 5%	180
	21st to end	Day	11% 9% 29% 32% 14% 5%	180
December	1st to 10th	Day	12% 14% 25% 26% 16% 7%	180
	11th to 20th	Day	8% 9% 34% 37% 11% 1	180
	21st to end	Day	8% 10% 34% 33% 13% 3	198
January	1st to 10th	Night	18% 12% 30% 25% 14% 1	760
	11th to 20th	Night	16% 8% 28% 32% 14% 1	760
	21st to end	Night	15% 7% 27% 33% 15% 2	836
February	1st to 10th	Night	14% 9% 33% 31% 11% 1	760
	11th to 20th	Night	11% 11% 29% 34% 13% 1	744
	21st to end	Night	10% 14% 30% 29% 15% 1	628
March	1st to 10th	Night	13% 8% 31% 36% 11% 1	760
	11th to 20th	Night	7% 11% 33% 33% 15% 1	760
	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% 7% 27% 34% 21% 3	734
	21st to end	Night	13% 10% 31% 31% 13% 3	792
November	1st to 10th	Night	14% 8% 31% 37% 10%	740
	11th to 20th	Night	15% 11% 31% 29% 12% 2	760
	21st to end	Night	14% 8% 30% 29% 16% 2	760
December	1st to 10th	Night	13% 8% 32% 32% 14% 2	760
	11th to 20th	Night	15% 6% 33% 36% 10%	760
	21st to end	Night	16% 9% 32% 35% 7% 1	836

Page generated at 2024-10-11 07:49:57. Version ac07

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