Ridge Park Campground
Clear Sky Chart
History

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

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	7% 7% 3 7% 4 4 5% 4 6% 8% 44%	131122
	Night	6% 9% 3 7% 5% 4 5% 4 6% 8% 43%	128308
Transparency	Day	35% 8% 15% 25% 14% 3	130823
	Night	37% 7% 16% 24% 13% 3	128184
Seeing	Day	13% 13% 31% 27% 14% 3	16818
	Night	11% 13% 36% 29% 10% 1	26010

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	3 13% 6% 13% 7% 6% 5% 4 6% 8% 30%	3179
	11th to 20th	Day	2 10% 6% 12% 6% 5% 9% 6% 5% 6% 34%	3269
	21st to end	Day	2 7% 3 9% 4 4 5% 4 7% 8% 49%	4004
February	1st to 10th	Day	5% 14% 5% 12% 5% 6% 4 4 7% 8% 30%	1712
	11th to 20th	Day	5% 12% 4 9% 6% 6% 7% 5% 7% 8% 31%	1755
	21st to end	Day	3 11% 5% 10% 6% 5% 4 5% 6% 8% 37%	1574
March	1st to 10th	Day	3 9% 3 9% 5% 5% 5% 4 6% 10% 41%	4601
	11th to 20th	Day	3 7% 3 10% 6% 5% 6% 4 5% 8% 43%	4999
	21st to end	Day	8% 15% 6% 11% 5% 5% 5% 5% 7% 7% 26%	5486
April	1st to 10th	Day	8% 12% 3 9% 5% 5% 5% 5% 6% 9% 32%	2434
	11th to 20th	Day	11% 13% 5% 8% 5% 4 5% 3 6% 7% 34%	2570
	21st to end	Day	11% 10% 3 6% 5% 5% 5% 5% 6% 9% 35%	2600
May	1st to 10th	Day	13% 12% 3 6% 3 3 4 4 5% 6% 41%	5987
	11th to 20th	Day	12% 7% 3 8% 5% 6% 7% 6% 8% 9% 30%	6600
	21st to end	Day	11% 6% 2 6% 5% 5% 5% 4 6% 8% 42%	7405
June	1st to 10th	Day	13% 7% 2 7% 5% 5% 5% 4 6% 9% 37%	3000
	11th to 20th	Day	15% 7% 3 6% 5% 5% 6% 5% 7% 7% 34%	3000
	21st to end	Day	8% 4 2 4 3 5% 5% 4 7% 8% 49%	3000
July	1st to 10th	Day	6% 3 1 4 3 4 4 3 6% 7% 58%	6780
	11th to 20th	Day	7% 3 1 4 3 3 4 4 7% 9% 55%	6780
	21st to end	Day	6% 4 1 3 2 3 3 3 5% 7% 63%	7178
August	1st to 10th	Day	9% 5% 1 5% 4 4 4 4 6% 9% 47%	4388
	11th to 20th	Day	5% 3 2 4 4 4 4 4 6% 8% 57%	4158
	21st to end	Day	7% 3 2 4 3 3 3 3 5% 7% 60%	4664
September	1st to 10th	Day	10% 5% 1 5% 3 4 3 2 5% 7% 56%	2461
	11th to 20th	Day	11% 6% 2 5% 4 3 4 3 5% 8% 49%	2200
	21st to end	Day	10% 5% 2 4 3 4 5% 4 5% 7% 51%	2200
October	1st to 10th	Day	7% 7% 2 5% 3 3 4 4 8% 9% 49%	3384
	11th to 20th	Day	5% 7% 2 6% 4 5% 4 4 6% 9% 49%	3166
	21st to end	Day	6% 6% 3 6% 3 4 4 5% 7% 8% 46%	3200
November	1st to 10th	Day	10% 13% 4 8% 5% 4 4 5% 5% 8% 34%	1710
	11th to 20th	Day	5% 9% 2 8% 5% 6% 5% 4 6% 10% 40%	1680
	21st to end	Day	4 10% 5% 8% 4 5% 4 4 7% 9% 39%	1554
December	1st to 10th	Day	2 8% 4 9% 5% 5% 6% 5% 7% 8% 40%	2304
	11th to 20th	Day	2 9% 4 10% 6% 7% 5% 4 7% 9% 36%	2642
	21st to end	Day	3 11% 4 10% 5% 5% 5% 4 6% 7% 40%	3498
January	1st to 10th	Night	3 13% 6% 12% 5% 5% 5% 5% 7% 8% 32%	6766
	11th to 20th	Night	2 12% 5% 10% 6% 6% 7% 4 6% 7% 35%	6674
	21st to end	Night	2 8% 4 10% 6% 5% 5% 4 6% 8% 44%	6952
February	1st to 10th	Night	5% 12% 5% 10% 6% 4 5% 4 6% 7% 35%	2687
	11th to 20th	Night	4 12% 5% 11% 6% 6% 6% 5% 7% 8% 31%	2532
	21st to end	Night	3 11% 5% 11% 7% 5% 5% 4 5% 7% 36%	2055
March	1st to 10th	Night	2 8% 4 8% 6% 5% 5% 4 6% 10% 40%	5293
	11th to 20th	Night	3 6% 3 8% 5% 5% 5% 5% 8% 10% 43%	5000
	21st to end	Night	10% 17% 6% 10% 5% 4 4 4 6% 9% 25%	5489
April	1st to 10th	Night	8% 11% 4 7% 5% 4 5% 4 5% 8% 38%	1962
	11th to 20th	Night	10% 12% 3 8% 4 5% 5% 5% 6% 7% 36%	1781
	21st to end	Night	10% 11% 3 7% 6% 4 6% 5% 5% 7% 37%	1800
May	1st to 10th	Night	12% 12% 3 7% 4 4 4 4 5% 7% 38%	3991
	11th to 20th	Night	9% 8% 3 8% 5% 5% 7% 4 7% 10% 34%	3297
	21st to end	Night	12% 5% 2 5% 4 4 5% 4 6% 8% 45%	3470
June	1st to 10th	Night	11% 6% 3 6% 4 3 4 5% 7% 7% 44%	1400
	11th to 20th	Night	14% 7% 2 5% 4 4 4 5% 7% 9% 39%	1400
	21st to end	Night	7% 4 1 3 4 5% 4 5% 7% 9% 52%	1400
July	1st to 10th	Night	5% 2 1 3 2 3 4 4 6% 9% 60%	3180
	11th to 20th	Night	6% 3 1 3 2 3 4 4 7% 8% 59%	3180
	21st to end	Night	5% 4 2 4 3 3 3 3 4 6% 62%	3648
August	1st to 10th	Night	9% 4 1 4 4 4 4 3 5% 8% 54%	2765
	11th to 20th	Night	4 3 1 6% 4 5% 6% 5% 8% 11% 47%	2901
	21st to end	Night	7% 3 1 5% 3 3 4 3 5% 7% 59%	3245
September	1st to 10th	Night	10% 5% 1 5% 3 3 3 3 5% 8% 55%	1934
	11th to 20th	Night	10% 5% 2 5% 4 3 4 3 5% 6% 52%	2200
	21st to end	Night	8% 6% 2 5% 3 3 4 4 5% 7% 52%	2200
October	1st to 10th	Night	6% 6% 2 4 3 3 4 4 6% 8% 54%	3809
	11th to 20th	Night	6% 8% 2 5% 4 4 4 4 6% 9% 50%	3979
	21st to end	Night	4 6% 3 7% 5% 6% 5% 4 6% 7% 47%	4600
November	1st to 10th	Night	9% 12% 3 7% 6% 5% 5% 4 6% 7% 38%	2787
	11th to 20th	Night	4 9% 3 7% 5% 5% 5% 5% 7% 8% 43%	2940
	21st to end	Night	4 10% 4 8% 5% 5% 4 3 7% 9% 41%	3062
December	1st to 10th	Night	3 8% 3 7% 5% 5% 6% 4 8% 10% 41%	4921
	11th to 20th	Night	3 9% 4 10% 6% 4 5% 5% 7% 10% 37%	5550
	21st to end	Night	2 10% 4 9% 5% 4 5% 4 7% 8% 42%	7458

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	49% 8% 13% 23% 6% 1	3179
	11th to 20th	Day	49% 7% 13% 16% 12% 4	3290
	21st to end	Day	31% 8% 18% 31% 11%	4004
February	1st to 10th	Day	49% 7% 17% 16% 8% 3	1712
	11th to 20th	Day	46% 10% 16% 19% 8% 2	1764
	21st to end	Day	44% 6% 16% 20% 11% 2	1574
March	1st to 10th	Day	34% 8% 14% 25% 17% 2	4601
	11th to 20th	Day	35% 8% 19% 25% 12% 1	5000
	21st to end	Day	52% 10% 18% 14% 6%	5486
April	1st to 10th	Day	46% 9% 15% 22% 7%	2434
	11th to 20th	Day	46% 7% 12% 23% 9% 1	2570
	21st to end	Day	43% 9% 15% 22% 10% 1	2600
May	1st to 10th	Day	43% 5% 10% 23% 15% 4	5987
	11th to 20th	Day	40% 12% 16% 23% 8% 1	6604
	21st to end	Day	34% 10% 15% 27% 14%	7406
June	1st to 10th	Day	42% 8% 17% 21% 11% 1	3000
	11th to 20th	Day	44% 9% 13% 20% 13% 2	3000
	21st to end	Day	29% 7% 19% 30% 13% 2	3000
July	1st to 10th	Day	23% 6% 14% 23% 26% 7%	6706
	11th to 20th	Day	23% 7% 15% 29% 20% 6%	6699
	21st to end	Day	19% 6% 13% 27% 20% 15%	6975
August	1st to 10th	Day	30% 7% 15% 25% 20% 3	4371
	11th to 20th	Day	23% 7% 15% 34% 18% 3	4197
	21st to end	Day	22% 5% 10% 39% 20% 3	4663
September	1st to 10th	Day	29% 5% 13% 25% 20% 9%	2461
	11th to 20th	Day	33% 7% 14% 27% 16% 4	2200
	21st to end	Day	32% 7% 13% 31% 15% 3	2200
October	1st to 10th	Day	29% 6% 13% 35% 15% 2	3384
	11th to 20th	Day	31% 5% 15% 29% 18% 1	3166
	21st to end	Day	33% 7% 12% 31% 16% 2	3200
November	1st to 10th	Day	47% 8% 13% 22% 8% 2	1710
	11th to 20th	Day	37% 7% 22% 22% 10% 1	1680
	21st to end	Day	38% 9% 21% 20% 11% 2	1554
December	1st to 10th	Day	38% 8% 18% 27% 6% 2	2304
	11th to 20th	Day	41% 8% 24% 23% 4 1	2644
	21st to end	Day	40% 7% 13% 22% 15% 3	3498
January	1st to 10th	Night	46% 8% 16% 23% 6% 1	6766
	11th to 20th	Night	47% 6% 15% 16% 14% 2	6715
	21st to end	Night	37% 7% 16% 27% 11% 1	6952
February	1st to 10th	Night	45% 9% 16% 17% 12% 2	2687
	11th to 20th	Night	48% 8% 16% 18% 9% 1	2533
	21st to end	Night	46% 6% 16% 20% 9% 2	2055
March	1st to 10th	Night	36% 8% 17% 24% 12% 4	5293
	11th to 20th	Night	31% 9% 20% 27% 12%	5000
	21st to end	Night	54% 8% 18% 15% 6% 1	5489
April	1st to 10th	Night	43% 7% 16% 25% 8%	1962
	11th to 20th	Night	44% 8% 12% 24% 11% 1	1781
	21st to end	Night	43% 8% 15% 24% 9% 1	1800
May	1st to 10th	Night	44% 6% 12% 23% 12% 3	3988
	11th to 20th	Night	38% 10% 15% 28% 8% 1	3297
	21st to end	Night	33% 9% 17% 28% 13% 1	3470
June	1st to 10th	Night	37% 8% 17% 28% 10% 1	1400
	11th to 20th	Night	39% 7% 16% 23% 13% 2	1400
	21st to end	Night	26% 9% 16% 29% 18% 2	1400
July	1st to 10th	Night	19% 5% 18% 25% 23% 9%	3145
	11th to 20th	Night	20% 7% 17% 31% 18% 8%	3138
	21st to end	Night	23% 6% 14% 25% 19% 13%	3546
August	1st to 10th	Night	27% 7% 13% 25% 21% 7%	2757
	11th to 20th	Night	27% 8% 17% 28% 17% 3	2928
	21st to end	Night	23% 5% 11% 36% 20% 5%	3245
September	1st to 10th	Night	29% 5% 12% 29% 18% 8%	1934
	11th to 20th	Night	31% 6% 14% 27% 17% 5%	2200
	21st to end	Night	30% 6% 14% 30% 16% 4	2200
October	1st to 10th	Night	27% 6% 11% 33% 19% 3	3809
	11th to 20th	Night	30% 6% 16% 29% 16% 3	3979
	21st to end	Night	34% 7% 14% 30% 14% 1	4600
November	1st to 10th	Night	44% 8% 16% 21% 10% 2	2787
	11th to 20th	Night	36% 9% 20% 21% 14%	2940
	21st to end	Night	39% 7% 22% 19% 10% 2	3062
December	1st to 10th	Night	35% 8% 24% 22% 10% 2	4921
	11th to 20th	Night	41% 9% 26% 18% 6% 1	5547
	21st to end	Night	37% 6% 14% 24% 15% 4	7458

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	11% 13% 36% 25% 9% 8%	200
	11th to 20th	Day	14% 14% 40% 21% 10% 2	200
	21st to end	Day	8% 18% 45% 22% 5% 2	220
February	1st to 10th	Day	14% 18% 40% 20% 5% 2	257
	11th to 20th	Day	9% 19% 41% 22% 6% 3	300
	21st to end	Day	14% 16% 37% 25% 7%	338
March	1st to 10th	Day	11% 21% 33% 23% 10% 2	500
	11th to 20th	Day	10% 17% 35% 26% 8% 4	500
	21st to end	Day	13% 17% 35% 25% 8% 2	550
April	1st to 10th	Day	15% 19% 34% 24% 6%	500
	11th to 20th	Day	16% 18% 33% 23% 10% 1	492
	21st to end	Day	13% 17% 34% 23% 11% 2	500
May	1st to 10th	Day	17% 11% 27% 26% 17% 3	545
	11th to 20th	Day	20% 9% 24% 26% 18% 4	725
	21st to end	Day	20% 9% 20% 29% 19% 4	789
June	1st to 10th	Day	14% 15% 26% 26% 15% 3	730
	11th to 20th	Day	19% 16% 30% 23% 11% 2	730
	21st to end	Day	9% 9% 29% 30% 18% 4	730
July	1st to 10th	Day	8% 5% 25% 35% 23% 4	721
	11th to 20th	Day	9% 6% 30% 37% 16% 2	718
	21st to end	Day	5% 7% 27% 36% 21% 4	710
August	1st to 10th	Day	10% 6% 24% 35% 21% 4	527
	11th to 20th	Day	6% 6% 24% 33% 23% 7%	517
	21st to end	Day	10% 9% 24% 32% 21% 4	583
September	1st to 10th	Day	10% 10% 29% 27% 20% 3	530
	11th to 20th	Day	13% 11% 28% 29% 15% 3	530
	21st to end	Day	16% 13% 34% 22% 11% 4	530
October	1st to 10th	Day	14% 13% 29% 26% 13% 4	405
	11th to 20th	Day	14% 16% 33% 21% 13% 3	330
	21st to end	Day	17% 23% 33% 18% 7% 1	363
November	1st to 10th	Day	22% 20% 35% 17% 5%	330
	11th to 20th	Day	17% 13% 46% 19% 5%	330
	21st to end	Day	11% 19% 42% 16% 7% 5%	264
December	1st to 10th	Day	13% 15% 47% 19% 6% 1	204
	11th to 20th	Day	14% 18% 43% 18% 7% 2	200
	21st to end	Day	14% 15% 36% 22% 10% 4	220
January	1st to 10th	Night	10% 19% 43% 21% 6% 1	1000
	11th to 20th	Night	10% 19% 42% 23% 7%	974
	21st to end	Night	9% 19% 43% 23% 6% 1	880
February	1st to 10th	Night	11% 16% 38% 24% 9% 3	800
	11th to 20th	Night	10% 15% 41% 27% 7% 1	784
	21st to end	Night	9% 15% 37% 26% 11% 1	660
March	1st to 10th	Night	9% 12% 41% 29% 9% 2	800
	11th to 20th	Night	9% 13% 40% 30% 8% 2	800
	21st to end	Night	13% 16% 34% 28% 8% 2	880
April	1st to 10th	Night	13% 14% 37% 26% 8% 1	710
	11th to 20th	Night	16% 11% 39% 26% 8%	593
	21st to end	Night	16% 13% 31% 32% 9%	600
May	1st to 10th	Night	13% 10% 29% 33% 15% 1	600
	11th to 20th	Night	13% 7% 27% 38% 13% 2	454
	21st to end	Night	22% 7% 24% 30% 15% 2	433
June	1st to 10th	Night	16% 9% 30% 34% 12% 1	400
	11th to 20th	Night	16% 11% 36% 27% 11%	400
	21st to end	Night	9% 5% 33% 39% 15% 1	400
July	1st to 10th	Night	7% 6% 26% 43% 18%	390
	11th to 20th	Night	9% 2 31% 44% 14% 1	388
	21st to end	Night	5% 4 27% 47% 15% 2	438
August	1st to 10th	Night	9% 3 22% 47% 18% 1	489
	11th to 20th	Night	7% 3 27% 42% 20% 1	594
	21st to end	Night	8% 5% 29% 43% 14%	660
September	1st to 10th	Night	13% 4 28% 39% 14% 1	650
	11th to 20th	Night	12% 6% 25% 37% 18% 2	800
	21st to end	Night	12% 9% 34% 32% 12% 1	800
October	1st to 10th	Night	14% 8% 33% 30% 14% 1	800
	11th to 20th	Night	14% 13% 36% 26% 10% 1	800
	21st to end	Night	12% 17% 41% 23% 6%	880
November	1st to 10th	Night	17% 18% 40% 22% 3	942
	11th to 20th	Night	12% 19% 45% 19% 5%	1050
	21st to end	Night	8% 16% 43% 24% 6% 1	1050
December	1st to 10th	Night	9% 17% 40% 24% 9% 1	1011
	11th to 20th	Night	8% 16% 45% 25% 7% 1	1000
	21st to end	Night	11% 16% 42% 23% 7% 1	1100

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