Hurricane Ridge Visitor Center
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Hurricane Ridge Visitor Center clear sky chart from 2005-11-06 to 2024-12-06.

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 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	10% 12% 4 9% 6% 5% 5% 4 5% 6% 34%	105765
	Night	7% 11% 4 9% 7% 6% 6% 5% 6% 7% 33%	102551
Transparency	Day	49% 8% 14% 16% 11% 2	105516
	Night	47% 9% 14% 16% 11% 3	102446
Seeing	Day	19% 18% 31% 21% 8% 2	15468
	Night	15% 11% 31% 26% 14% 3	23730

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	8% 21% 7% 14% 9% 5% 6% 4 7% 6% 14%	2219
	11th to 20th	Day	7% 17% 5% 10% 8% 7% 6% 5% 6% 8% 22%	2245
	21st to end	Day	8% 19% 5% 14% 10% 8% 7% 5% 5% 7% 14%	2954
February	1st to 10th	Day	11% 17% 4 10% 8% 7% 6% 4 6% 8% 19%	1710
	11th to 20th	Day	9% 18% 7% 12% 7% 7% 6% 4 5% 5% 20%	1665
	21st to end	Day	8% 22% 7% 12% 8% 7% 6% 5% 5% 5% 15%	1422
March	1st to 10th	Day	3 15% 6% 11% 9% 8% 8% 7% 7% 8% 18%	3310
	11th to 20th	Day	5% 18% 5% 9% 6% 5% 5% 4 5% 6% 32%	3490
	21st to end	Day	11% 24% 5% 11% 6% 6% 5% 4 4 6% 18%	3881
April	1st to 10th	Day	11% 21% 6% 11% 7% 6% 6% 5% 7% 6% 14%	2280
	11th to 20th	Day	13% 20% 6% 10% 6% 5% 5% 4 4 5% 21%	2345
	21st to end	Day	15% 20% 5% 9% 6% 6% 5% 4 4 5% 20%	2470
May	1st to 10th	Day	14% 15% 4 9% 6% 4 4 3 4 4 34%	4417
	11th to 20th	Day	9% 9% 3 8% 5% 5% 5% 5% 7% 9% 38%	4377
	21st to end	Day	18% 17% 4 9% 6% 5% 5% 3 5% 6% 21%	4813
June	1st to 10th	Day	19% 13% 3 9% 7% 5% 5% 4 5% 6% 25%	2845
	11th to 20th	Day	16% 11% 4 10% 7% 6% 5% 4 6% 7% 25%	2850
	21st to end	Day	13% 7% 3 7% 5% 5% 5% 5% 6% 7% 37%	2850
July	1st to 10th	Day	6% 4 1 3 3 2 3 2 3 5% 69%	4740
	11th to 20th	Day	6% 3 1 3 3 2 2 2 4 5% 69%	4740
	21st to end	Day	7% 4 1 5% 3 3 4 3 4 7% 60%	4800
August	1st to 10th	Day	3 3 1 3 2 3 3 3 5% 7% 67%	4230
	11th to 20th	Day	9% 9% 3 7% 5% 6% 7% 4 6% 7% 38%	4026
	21st to end	Day	10% 6% 3 7% 5% 4 4 4 5% 6% 47%	4413
September	1st to 10th	Day	9% 6% 2 5% 3 3 4 3 5% 7% 53%	2280
	11th to 20th	Day	10% 9% 3 8% 6% 4 4 3 5% 7% 41%	2247
	21st to end	Day	10% 8% 3 9% 5% 5% 5% 4 5% 7% 41%	2019
October	1st to 10th	Day	10% 7% 3 8% 6% 5% 6% 5% 7% 8% 34%	3180
	11th to 20th	Day	10% 11% 4 12% 7% 5% 5% 4 6% 7% 28%	3161
	21st to end	Day	9% 10% 4 11% 8% 7% 6% 5% 6% 7% 26%	3278
November	1st to 10th	Day	13% 15% 6% 12% 10% 7% 6% 4 5% 6% 15%	1568
	11th to 20th	Day	10% 16% 5% 10% 7% 7% 6% 4 7% 6% 22%	1600
	21st to end	Day	11% 16% 4 10% 7% 6% 6% 4 6% 7% 22%	1600
December	1st to 10th	Day	7% 13% 5% 10% 8% 6% 5% 5% 6% 7% 27%	1560
	11th to 20th	Day	7% 16% 5% 12% 9% 8% 7% 5% 5% 5% 20%	1738
	21st to end	Day	8% 15% 5% 13% 8% 8% 7% 6% 8% 7% 15%	2442
January	1st to 10th	Night	7% 19% 6% 14% 9% 8% 7% 5% 5% 5% 15%	4726
	11th to 20th	Night	6% 12% 5% 12% 8% 7% 7% 5% 7% 9% 24%	4637
	21st to end	Night	9% 15% 5% 14% 9% 9% 7% 6% 6% 6% 14%	4707
February	1st to 10th	Night	10% 16% 5% 11% 8% 6% 6% 4 6% 8% 20%	2470
	11th to 20th	Night	7% 16% 5% 12% 8% 7% 5% 4 6% 6% 24%	2402
	21st to end	Night	9% 20% 7% 14% 8% 5% 5% 4 6% 6% 17%	2030
March	1st to 10th	Night	3 10% 4 11% 8% 9% 8% 6% 10% 10% 21%	3560
	11th to 20th	Night	3 11% 3 7% 7% 7% 6% 5% 7% 8% 36%	3489
	21st to end	Night	7% 16% 6% 13% 9% 7% 9% 5% 6% 6% 17%	3772
April	1st to 10th	Night	7% 16% 4 12% 8% 6% 7% 4 7% 7% 21%	1900
	11th to 20th	Night	7% 12% 5% 10% 7% 6% 6% 5% 7% 8% 27%	1781
	21st to end	Night	9% 13% 4 10% 8% 5% 7% 4 6% 7% 27%	1710
May	1st to 10th	Night	7% 9% 3 9% 5% 5% 4 3 4 5% 45%	2541
	11th to 20th	Night	5% 6% 2 6% 4 4 4 4 6% 8% 52%	2516
	21st to end	Night	8% 9% 4 9% 7% 5% 7% 4 6% 7% 33%	2762
June	1st to 10th	Night	10% 7% 3 8% 6% 5% 5% 5% 5% 6% 40%	1332
	11th to 20th	Night	6% 9% 3 6% 7% 5% 5% 4 8% 7% 40%	1330
	21st to end	Night	5% 4 2 7% 4 4 5% 6% 6% 7% 52%	1330
July	1st to 10th	Night	3 2 1 4 3 3 2 2 3 4 74%	2220
	11th to 20th	Night	2 2 1 2 2 2 2 2 3 5% 76%	2220
	21st to end	Night	5% 4 1 4 3 3 3 3 3 5% 66%	2752
August	1st to 10th	Night	2 2 1 2 2 2 2 3 4 5% 75%	2703
	11th to 20th	Night	7% 7% 2 6% 6% 5% 4 4 5% 7% 49%	2812
	21st to end	Night	9% 5% 2 4 4 3 5% 4 5% 8% 53%	3257
September	1st to 10th	Night	5% 3 1 5% 4 3 4 3 6% 7% 60%	1900
	11th to 20th	Night	8% 7% 2 6% 5% 5% 5% 4 6% 7% 46%	1929
	21st to end	Night	8% 7% 2 7% 6% 5% 4 4 5% 7% 44%	2161
October	1st to 10th	Night	8% 7% 2 6% 5% 4 5% 5% 8% 8% 43%	3800
	11th to 20th	Night	11% 8% 4 10% 6% 6% 6% 4 6% 7% 30%	3777
	21st to end	Night	9% 9% 3 10% 7% 6% 6% 5% 7% 8% 30%	4281
November	1st to 10th	Night	12% 12% 5% 11% 8% 7% 7% 5% 6% 6% 21%	2730
	11th to 20th	Night	10% 15% 5% 9% 7% 7% 7% 5% 6% 7% 22%	2800
	21st to end	Night	8% 15% 3 12% 8% 7% 7% 6% 7% 6% 21%	2800
December	1st to 10th	Night	6% 14% 4 11% 7% 6% 7% 5% 6% 7% 26%	2736
	11th to 20th	Night	7% 15% 5% 13% 9% 8% 7% 5% 6% 6% 20%	3464
	21st to end	Night	6% 15% 5% 12% 9% 9% 8% 7% 7% 7% 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	66% 9% 11% 8% 4 1	2219
	11th to 20th	Day	54% 9% 15% 13% 8% 2	2266
	21st to end	Day	68% 12% 8% 6% 4 1	2954
February	1st to 10th	Day	61% 10% 14% 8% 6% 1	1710
	11th to 20th	Day	63% 9% 10% 10% 6% 1	1674
	21st to end	Day	67% 7% 12% 10% 4	1422
March	1st to 10th	Day	55% 10% 19% 10% 5% 1	3310
	11th to 20th	Day	51% 7% 12% 22% 8% 1	3490
	21st to end	Day	67% 6% 14% 10% 3	3881
April	1st to 10th	Day	68% 9% 12% 10% 2	2280
	11th to 20th	Day	66% 6% 9% 11% 8% 1	2345
	21st to end	Day	65% 7% 10% 12% 5% 1	2470
May	1st to 10th	Day	52% 5% 16% 18% 9%	4417
	11th to 20th	Day	41% 8% 26% 17% 7%	4380
	21st to end	Day	64% 8% 14% 10% 3	4814
June	1st to 10th	Day	60% 9% 15% 9% 6% 1	2845
	11th to 20th	Day	62% 9% 14% 10% 5% 1	2850
	21st to end	Day	47% 10% 17% 17% 8% 2	2850
July	1st to 10th	Day	22% 5% 9% 16% 31% 17%	4666
	11th to 20th	Day	19% 6% 9% 25% 30% 11%	4659
	21st to end	Day	24% 8% 16% 31% 17% 4	4648
August	1st to 10th	Day	18% 8% 12% 27% 29% 6%	4213
	11th to 20th	Day	38% 11% 18% 22% 9% 1	4065
	21st to end	Day	38% 7% 13% 26% 14% 2	4412
September	1st to 10th	Day	32% 6% 16% 23% 18% 4	2280
	11th to 20th	Day	43% 7% 12% 18% 16% 3	2247
	21st to end	Day	42% 8% 18% 18% 12% 3	2019
October	1st to 10th	Day	43% 9% 13% 23% 11% 1	3180
	11th to 20th	Day	53% 10% 12% 15% 10% 1	3161
	21st to end	Day	51% 11% 14% 15% 7% 2	3278
November	1st to 10th	Day	69% 6% 10% 9% 5% 1	1568
	11th to 20th	Day	61% 11% 7% 12% 7% 2	1600
	21st to end	Day	59% 9% 8% 11% 11% 2	1600
December	1st to 10th	Day	56% 9% 11% 13% 9% 2	1560
	11th to 20th	Day	63% 8% 13% 11% 4 1	1741
	21st to end	Day	62% 13% 11% 9% 4	2442
January	1st to 10th	Night	64% 11% 10% 9% 5% 1	4726
	11th to 20th	Night	51% 9% 15% 13% 10% 2	4678
	21st to end	Night	66% 13% 8% 6% 5% 2	4707
February	1st to 10th	Night	59% 9% 13% 10% 7% 2	2470
	11th to 20th	Night	58% 10% 10% 12% 7% 2	2404
	21st to end	Night	66% 8% 11% 12% 4	2030
March	1st to 10th	Night	48% 12% 23% 11% 6% 1	3560
	11th to 20th	Night	42% 9% 17% 19% 12% 1	3490
	21st to end	Night	64% 10% 15% 10% 2	3772
April	1st to 10th	Night	60% 8% 16% 12% 4	1900
	11th to 20th	Night	53% 8% 14% 14% 10% 1	1781
	21st to end	Night	56% 8% 11% 14% 10% 1	1710
May	1st to 10th	Night	39% 6% 15% 25% 14% 1	2541
	11th to 20th	Night	31% 8% 25% 22% 12% 2	2516
	21st to end	Night	48% 13% 18% 17% 4 1	2762
June	1st to 10th	Night	47% 9% 16% 19% 7% 2	1332
	11th to 20th	Night	42% 10% 23% 18% 7%	1330
	21st to end	Night	29% 11% 24% 23% 9% 4	1330
July	1st to 10th	Night	17% 5% 11% 17% 27% 22%	2185
	11th to 20th	Night	12% 5% 11% 20% 32% 19%	2178
	21st to end	Night	23% 6% 14% 25% 25% 9%	2665
August	1st to 10th	Night	15% 5% 10% 26% 37% 6%	2695
	11th to 20th	Night	30% 11% 21% 23% 12% 4	2839
	21st to end	Night	28% 8% 15% 29% 18% 2	3257
September	1st to 10th	Night	24% 8% 16% 25% 21% 6%	1900
	11th to 20th	Night	38% 8% 12% 19% 17% 6%	1929
	21st to end	Night	40% 8% 13% 18% 16% 5%	2161
October	1st to 10th	Night	37% 6% 12% 27% 16% 2	3800
	11th to 20th	Night	52% 7% 12% 17% 10% 2	3777
	21st to end	Night	47% 12% 11% 17% 11% 2	4281
November	1st to 10th	Night	62% 8% 12% 13% 5% 1	2730
	11th to 20th	Night	59% 12% 11% 8% 6% 3	2800
	21st to end	Night	58% 10% 10% 9% 10% 2	2800
December	1st to 10th	Night	55% 12% 11% 11% 9% 2	2736
	11th to 20th	Night	61% 10% 12% 11% 5% 1	3460
	21st to end	Night	59% 11% 15% 10% 5% 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	24% 21% 24% 17% 9% 4	180
	11th to 20th	Day	17% 19% 32% 14% 15% 2	180
	21st to end	Day	24% 20% 29% 17% 8% 3	293
February	1st to 10th	Day	24% 21% 35% 15% 3 1	370
	11th to 20th	Day	24% 22% 36% 13% 5%	365
	21st to end	Day	29% 23% 31% 13% 3 1	312
March	1st to 10th	Day	22% 25% 33% 16% 3	460
	11th to 20th	Day	20% 24% 30% 22% 4	460
	21st to end	Day	24% 26% 35% 12% 3	506
April	1st to 10th	Day	26% 23% 30% 16% 5%	460
	11th to 20th	Day	29% 22% 27% 16% 5% 1	452
	21st to end	Day	31% 22% 28% 14% 4 1	460
May	1st to 10th	Day	25% 17% 29% 20% 7% 2	463
	11th to 20th	Day	24% 16% 27% 22% 8% 2	488
	21st to end	Day	22% 13% 34% 19% 9% 3	529
June	1st to 10th	Day	25% 17% 29% 20% 7% 3	675
	11th to 20th	Day	20% 21% 32% 18% 7% 1	680
	21st to end	Day	14% 15% 35% 24% 9% 3	680
July	1st to 10th	Day	13% 10% 32% 32% 11% 2	671
	11th to 20th	Day	12% 12% 30% 30% 11% 5%	668
	21st to end	Day	7% 11% 28% 35% 13% 7%	541
August	1st to 10th	Day	7% 9% 29% 34% 14% 6%	487
	11th to 20th	Day	8% 9% 29% 35% 13% 6%	477
	21st to end	Day	11% 18% 31% 26% 11% 3	539
September	1st to 10th	Day	12% 12% 38% 28% 9% 1	490
	11th to 20th	Day	14% 13% 38% 24% 9% 2	490
	21st to end	Day	15% 18% 33% 24% 8% 2	490
October	1st to 10th	Day	18% 18% 31% 20% 12% 1	490
	11th to 20th	Day	22% 21% 29% 15% 10% 3	490
	21st to end	Day	22% 23% 32% 13% 7% 2	454
November	1st to 10th	Day	24% 24% 30% 15% 8% 1	200
	11th to 20th	Day	23% 21% 25% 19% 8% 6%	200
	21st to end	Day	22% 16% 27% 21% 7% 8%	200
December	1st to 10th	Day	22% 15% 26% 18% 14% 6%	190
	11th to 20th	Day	17% 18% 36% 17% 11% 1	180
	21st to end	Day	20% 12% 38% 23% 6% 2	198
January	1st to 10th	Night	22% 19% 31% 16% 9% 3	850
	11th to 20th	Night	18% 15% 30% 22% 12% 3	832
	21st to end	Night	21% 12% 32% 22% 10% 2	836
February	1st to 10th	Night	21% 11% 40% 20% 8% 1	760
	11th to 20th	Night	16% 14% 31% 30% 8% 1	744
	21st to end	Night	20% 15% 34% 23% 6% 1	628
March	1st to 10th	Night	14% 16% 37% 22% 10% 1	760
	11th to 20th	Night	14% 15% 39% 22% 9% 2	760
	21st to end	Night	15% 15% 35% 26% 8% 1	836
April	1st to 10th	Night	17% 11% 35% 26% 9% 1	760
	11th to 20th	Night	14% 11% 41% 23% 9% 2	653
	21st to end	Night	14% 7% 42% 25% 10% 2	570
May	1st to 10th	Night	9% 7% 29% 36% 14% 4	381
	11th to 20th	Night	11% 5% 24% 35% 22% 3	374
	21st to end	Night	13% 6% 22% 35% 23% 1	411
June	1st to 10th	Night	12% 6% 26% 34% 20% 2	380
	11th to 20th	Night	9% 4 35% 35% 16% 1	380
	21st to end	Night	6% 3 25% 39% 23% 4	380
July	1st to 10th	Night	6% 2 14% 36% 38% 3	370
	11th to 20th	Night	4 4 16% 40% 30% 5%	368
	21st to end	Night	3 3 13% 40% 32% 9%	416
August	1st to 10th	Night	5% 3 13% 32% 36% 12%	474
	11th to 20th	Night	4 2 11% 36% 35% 12%	564
	21st to end	Night	8% 4 24% 33% 27% 5%	686
September	1st to 10th	Night	7% 2 23% 37% 26% 6%	760
	11th to 20th	Night	12% 4 22% 29% 25% 8%	760
	21st to end	Night	13% 9% 23% 33% 18% 4	760
October	1st to 10th	Night	13% 7% 29% 28% 21% 3	760
	11th to 20th	Night	16% 11% 29% 25% 14% 5%	760
	21st to end	Night	15% 14% 39% 20% 8% 3	836
November	1st to 10th	Night	20% 14% 40% 20% 6%	780
	11th to 20th	Night	21% 17% 36% 17% 8% 2	800
	21st to end	Night	19% 16% 37% 16% 7% 4	800
December	1st to 10th	Night	16% 13% 33% 24% 11% 2	782
	11th to 20th	Night	19% 16% 41% 18% 6% 1	824
	21st to end	Night	22% 18% 38% 16% 5% 1	935

Page generated at 2024-12-03 03:45:08. Version ac07

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