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 2024-11-10.

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	7% 8% 3 7% 4 4 5% 4 6% 8% 44%	105543
	Night	6% 8% 3 7% 5% 4 5% 4 6% 8% 43%	102189
Transparency	Day	35% 8% 15% 25% 13% 3	105289
	Night	36% 8% 16% 24% 13% 3	102089
Seeing	Day	13% 13% 30% 27% 14% 3	15431
	Night	11% 12% 36% 29% 10% 1	24601

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 11% 4 11% 6% 5% 5% 5% 8% 10% 33%	2219
	11th to 20th	Day	3 9% 5% 12% 7% 5% 10% 6% 5% 6% 32%	2267
	21st to end	Day	3 9% 2 8% 5% 5% 5% 3 7% 9% 45%	2794
February	1st to 10th	Day	5% 14% 5% 12% 5% 5% 4 4 7% 8% 30%	1626
	11th to 20th	Day	6% 12% 4 9% 6% 6% 7% 5% 7% 8% 31%	1665
	21st to end	Day	4 11% 5% 10% 6% 5% 4 5% 6% 8% 36%	1497
March	1st to 10th	Day	2 9% 3 10% 6% 6% 6% 4 6% 9% 39%	3195
	11th to 20th	Day	4 8% 2 7% 4 3 4 4 6% 9% 48%	3489
	21st to end	Day	10% 15% 5% 11% 5% 4 4 4 6% 7% 29%	3825
April	1st to 10th	Day	9% 13% 4 9% 5% 5% 5% 5% 7% 9% 31%	2312
	11th to 20th	Day	11% 13% 5% 8% 5% 4 5% 3 6% 7% 34%	2440
	21st to end	Day	11% 10% 3 6% 5% 5% 5% 5% 6% 9% 34%	2470
May	1st to 10th	Day	16% 17% 4 8% 4 4 4 4 4 6% 31%	4189
	11th to 20th	Day	10% 7% 3 8% 5% 6% 6% 6% 8% 9% 33%	4599
	21st to end	Day	15% 7% 2 6% 6% 6% 6% 5% 7% 8% 33%	5161
June	1st to 10th	Day	14% 7% 2 7% 5% 5% 5% 4 6% 9% 36%	2850
	11th to 20th	Day	15% 7% 3 6% 5% 5% 6% 5% 7% 7% 34%	2850
	21st to end	Day	7% 4 2 4 3 5% 5% 4 7% 8% 50%	2850
July	1st to 10th	Day	4 3 1 4 3 4 4 4 6% 8% 57%	4740
	11th to 20th	Day	3 2 1 3 2 3 3 3 6% 9% 63%	4740
	21st to end	Day	2 2 1 2 2 2 3 3 5% 7% 70%	4996
August	1st to 10th	Day	9% 5% 1 5% 4 4 4 4 6% 9% 48%	4253
	11th to 20th	Day	5% 3 2 4 4 4 4 4 6% 8% 57%	4028
	21st to end	Day	7% 3 2 4 3 3 3 3 5% 7% 60%	4521
September	1st to 10th	Day	11% 4 1 5% 3 4 3 2 5% 6% 56%	2338
	11th to 20th	Day	12% 6% 2 5% 4 3 3 3 5% 8% 49%	2090
	21st to end	Day	11% 5% 2 4 3 4 5% 4 5% 7% 51%	2090
October	1st to 10th	Day	7% 7% 2 5% 3 3 4 4 8% 9% 49%	3280
	11th to 20th	Day	5% 7% 2 6% 4 5% 3 4 6% 10% 49%	3069
	21st to end	Day	6% 6% 4 6% 3 4 4 5% 7% 8% 46%	3101
November	1st to 10th	Day	11% 13% 4 8% 4 4 4 4 5% 8% 34%	1619
	11th to 20th	Day	5% 9% 2 7% 5% 6% 5% 5% 6% 10% 40%	1520
	21st to end	Day	3 10% 5% 8% 4 5% 5% 4 8% 9% 40%	1406
December	1st to 10th	Day	3 12% 5% 9% 5% 5% 6% 5% 6% 7% 36%	1330
	11th to 20th	Day	3 12% 4 9% 6% 7% 6% 5% 6% 9% 33%	1682
	21st to end	Day	3 9% 4 7% 5% 4 5% 4 6% 8% 45%	2442
January	1st to 10th	Night	3 10% 5% 11% 5% 5% 5% 5% 8% 9% 34%	4726
	11th to 20th	Night	3 12% 6% 9% 5% 6% 7% 5% 6% 8% 34%	4662
	21st to end	Night	3 9% 4 8% 5% 4 5% 4 6% 9% 43%	4862
February	1st to 10th	Night	5% 11% 5% 10% 6% 4 5% 4 6% 7% 36%	2553
	11th to 20th	Night	4 12% 5% 10% 6% 6% 6% 5% 7% 8% 32%	2402
	21st to end	Night	3 11% 5% 11% 8% 5% 5% 4 5% 7% 35%	1956
March	1st to 10th	Night	3 8% 4 10% 8% 6% 6% 5% 6% 7% 38%	3679
	11th to 20th	Night	3 7% 3 6% 4 4 4 4 7% 9% 48%	3490
	21st to end	Night	11% 19% 6% 12% 4 4 4 3 5% 7% 25%	3828
April	1st to 10th	Night	8% 11% 4 7% 5% 4 5% 4 5% 8% 38%	1865
	11th to 20th	Night	11% 12% 4 8% 4 5% 5% 5% 5% 6% 35%	1691
	21st to end	Night	11% 11% 3 7% 6% 4 5% 5% 5% 7% 37%	1710
May	1st to 10th	Night	15% 15% 4 8% 5% 4 4 3 5% 6% 30%	2779
	11th to 20th	Night	8% 7% 3 7% 5% 4 6% 4 7% 9% 40%	2295
	21st to end	Night	16% 7% 2 7% 5% 5% 6% 5% 7% 9% 31%	2414
June	1st to 10th	Night	11% 6% 3 7% 4 3 3 5% 7% 7% 42%	1330
	11th to 20th	Night	15% 7% 3 5% 4 4 4 4 7% 9% 38%	1330
	21st to end	Night	7% 4 1 3 4 5% 4 5% 7% 9% 53%	1330
July	1st to 10th	Night	4 3 1 4 3 3 4 4 6% 9% 59%	2220
	11th to 20th	Night	3 2 1 2 2 3 4 4 6% 8% 63%	2220
	21st to end	Night	3 3 1 3 3 3 3 3 4 6% 69%	2539
August	1st to 10th	Night	10% 4 1 4 4 4 4 3 5% 8% 54%	2680
	11th to 20th	Night	4 3 1 6% 4 5% 6% 5% 8% 11% 47%	2811
	21st to end	Night	7% 3 1 5% 3 3 4 3 6% 7% 58%	3146
September	1st to 10th	Night	10% 6% 1 5% 3 3 4 3 5% 7% 54%	1837
	11th to 20th	Night	10% 5% 2 5% 3 4 4 3 5% 6% 51%	2090
	21st to end	Night	8% 6% 2 5% 3 4 4 4 6% 7% 52%	2090
October	1st to 10th	Night	6% 6% 2 4 3 3 4 4 6% 8% 54%	3693
	11th to 20th	Night	6% 8% 2 5% 4 4 4 4 6% 9% 50%	3856
	21st to end	Night	4 6% 3 7% 5% 6% 5% 4 6% 7% 46%	4457
November	1st to 10th	Night	10% 12% 4 6% 5% 5% 4 4 6% 7% 37%	2644
	11th to 20th	Night	4 10% 3 6% 5% 5% 5% 4 7% 8% 44%	2660
	21st to end	Night	4 11% 4 7% 5% 5% 4 4 7% 8% 42%	2770
December	1st to 10th	Night	4 11% 4 9% 7% 6% 5% 4 6% 7% 38%	2850
	11th to 20th	Night	3 8% 4 10% 6% 4 5% 4 7% 10% 39%	3510
	21st to end	Night	3 9% 3 8% 5% 4 4 4 7% 8% 46%	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	41% 10% 18% 23% 8% 1	2219
	11th to 20th	Day	50% 8% 12% 13% 12% 5%	2288
	21st to end	Day	33% 10% 21% 30% 6%	2794
February	1st to 10th	Day	49% 8% 18% 17% 6% 2	1626
	11th to 20th	Day	46% 11% 16% 18% 7% 2	1674
	21st to end	Day	46% 6% 16% 20% 10% 2	1497
March	1st to 10th	Day	36% 10% 17% 24% 13%	3195
	11th to 20th	Day	30% 9% 25% 27% 8% 1	3490
	21st to end	Day	51% 10% 17% 16% 5%	3825
April	1st to 10th	Day	47% 10% 16% 21% 6%	2312
	11th to 20th	Day	47% 7% 13% 22% 9% 1	2440
	21st to end	Day	44% 8% 16% 22% 9% 1	2470
May	1st to 10th	Day	53% 6% 11% 24% 5%	4189
	11th to 20th	Day	37% 13% 17% 24% 9% 1	4603
	21st to end	Day	42% 13% 16% 20% 8% 1	5162
June	1st to 10th	Day	43% 8% 17% 20% 11% 1	2850
	11th to 20th	Day	45% 9% 13% 19% 12% 2	2850
	21st to end	Day	29% 7% 19% 30% 13% 2	2850
July	1st to 10th	Day	22% 7% 14% 27% 22% 8%	4666
	11th to 20th	Day	16% 5% 12% 34% 25% 9%	4659
	21st to end	Day	12% 5% 9% 25% 28% 21%	4838
August	1st to 10th	Day	30% 7% 14% 25% 21% 3	4236
	11th to 20th	Day	23% 7% 15% 35% 17% 3	4067
	21st to end	Day	22% 5% 11% 40% 19% 3	4520
September	1st to 10th	Day	30% 5% 12% 24% 20% 9%	2338
	11th to 20th	Day	33% 7% 14% 26% 16% 4	2090
	21st to end	Day	32% 7% 13% 31% 14% 3	2090
October	1st to 10th	Day	29% 6% 13% 35% 15% 2	3280
	11th to 20th	Day	30% 5% 16% 29% 18% 1	3069
	21st to end	Day	34% 7% 12% 31% 15% 2	3101
November	1st to 10th	Day	48% 8% 13% 21% 8% 2	1619
	11th to 20th	Day	38% 8% 22% 22% 10% 1	1520
	21st to end	Day	36% 10% 21% 20% 11% 2	1406
December	1st to 10th	Day	44% 8% 17% 19% 8% 4	1330
	11th to 20th	Day	43% 8% 23% 21% 4 1	1684
	21st to end	Day	33% 8% 16% 23% 15% 4	2442
January	1st to 10th	Night	41% 9% 18% 23% 7% 1	4726
	11th to 20th	Night	47% 7% 15% 14% 14% 3	4703
	21st to end	Night	36% 9% 20% 27% 8%	4862
February	1st to 10th	Night	44% 9% 16% 17% 12% 2	2553
	11th to 20th	Night	47% 8% 16% 18% 10% 1	2403
	21st to end	Night	47% 6% 16% 19% 9% 2	1956
March	1st to 10th	Night	41% 10% 17% 21% 11%	3679
	11th to 20th	Night	29% 10% 26% 25% 10%	3490
	21st to end	Night	58% 8% 15% 15% 4 1	3828
April	1st to 10th	Night	44% 7% 17% 24% 8%	1865
	11th to 20th	Night	45% 8% 12% 24% 10% 1	1691
	21st to end	Night	43% 8% 15% 24% 8% 1	1710
May	1st to 10th	Night	53% 7% 14% 19% 7% 1	2779
	11th to 20th	Night	32% 10% 17% 29% 11% 1	2295
	21st to end	Night	43% 10% 18% 21% 8%	2414
June	1st to 10th	Night	38% 8% 17% 27% 9% 1	1330
	11th to 20th	Night	40% 7% 16% 23% 12% 2	1330
	21st to end	Night	25% 9% 16% 29% 19% 3	1330
July	1st to 10th	Night	19% 6% 17% 29% 24% 6%	2185
	11th to 20th	Night	15% 7% 14% 30% 22% 12%	2178
	21st to end	Night	16% 4 8% 26% 27% 18%	2458
August	1st to 10th	Night	27% 7% 12% 25% 21% 8%	2672
	11th to 20th	Night	28% 8% 17% 28% 17% 3	2838
	21st to end	Night	23% 5% 12% 36% 19% 5%	3146
September	1st to 10th	Night	30% 5% 12% 28% 18% 8%	1837
	11th to 20th	Night	32% 6% 14% 27% 16% 5%	2090
	21st to end	Night	31% 6% 14% 30% 15% 4	2090
October	1st to 10th	Night	27% 6% 11% 33% 19% 3	3693
	11th to 20th	Night	30% 6% 16% 29% 16% 3	3856
	21st to end	Night	34% 7% 13% 30% 14% 1	4457
November	1st to 10th	Night	44% 8% 15% 20% 10% 2	2644
	11th to 20th	Night	35% 9% 20% 21% 14% 1	2660
	21st to end	Night	38% 8% 22% 20% 11% 2	2770
December	1st to 10th	Night	43% 9% 15% 20% 10% 2	2850
	11th to 20th	Night	38% 10% 26% 20% 6% 1	3507
	21st to end	Night	33% 7% 16% 24% 15% 5%	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	10% 12% 37% 25% 8% 8%	180
	11th to 20th	Day	14% 12% 39% 22% 11% 2	180
	21st to end	Day	8% 16% 43% 24% 6% 3	198
February	1st to 10th	Day	14% 19% 39% 20% 5% 3	231
	11th to 20th	Day	10% 20% 39% 21% 6% 4	270
	21st to end	Day	12% 15% 38% 27% 8%	309
March	1st to 10th	Day	11% 21% 34% 23% 10% 1	460
	11th to 20th	Day	10% 16% 34% 28% 9% 5%	460
	21st to end	Day	12% 17% 35% 25% 8% 2	506
April	1st to 10th	Day	15% 20% 35% 24% 6%	460
	11th to 20th	Day	17% 16% 32% 24% 10% 1	452
	21st to end	Day	14% 17% 34% 22% 11% 2	460
May	1st to 10th	Day	17% 10% 27% 25% 17% 3	503
	11th to 20th	Day	19% 8% 24% 27% 19% 4	675
	21st to end	Day	21% 9% 19% 28% 19% 4	734
June	1st to 10th	Day	15% 15% 26% 26% 15% 3	680
	11th to 20th	Day	19% 16% 29% 22% 11% 3	680
	21st to end	Day	9% 9% 28% 31% 18% 4	680
July	1st to 10th	Day	8% 5% 24% 36% 23% 4	671
	11th to 20th	Day	8% 6% 30% 37% 17% 2	668
	21st to end	Day	3 7% 27% 37% 21% 4	659
August	1st to 10th	Day	10% 5% 25% 35% 21% 4	487
	11th to 20th	Day	6% 6% 20% 34% 25% 8%	477
	21st to end	Day	10% 10% 24% 29% 22% 5%	539
September	1st to 10th	Day	11% 10% 30% 27% 20% 2	490
	11th to 20th	Day	14% 11% 29% 28% 14% 3	490
	21st to end	Day	17% 14% 31% 23% 11% 4	490
October	1st to 10th	Day	14% 13% 28% 27% 13% 5%	371
	11th to 20th	Day	14% 15% 32% 22% 14% 3	300
	21st to end	Day	16% 22% 34% 19% 8% 2	330
November	1st to 10th	Day	21% 19% 35% 20% 6%	297
	11th to 20th	Day	17% 11% 48% 21% 4	270
	21st to end	Day	7% 19% 43% 16% 8% 6%	216
December	1st to 10th	Day	12% 14% 48% 18% 7% 1	180
	11th to 20th	Day	13% 17% 44% 17% 7% 2	180
	21st to end	Day	13% 13% 38% 22% 10% 4	198
January	1st to 10th	Night	9% 19% 43% 21% 6% 1	950
	11th to 20th	Night	10% 17% 42% 23% 7%	926
	21st to end	Night	8% 19% 41% 24% 6% 2	836
February	1st to 10th	Night	12% 16% 37% 24% 9% 3	760
	11th to 20th	Night	10% 15% 40% 27% 7% 1	744
	21st to end	Night	9% 13% 37% 27% 12% 1	628
March	1st to 10th	Night	9% 11% 41% 29% 9% 2	760
	11th to 20th	Night	9% 13% 39% 30% 8% 2	760
	21st to end	Night	13% 14% 34% 29% 8% 2	836
April	1st to 10th	Night	14% 14% 37% 26% 8% 1	675
	11th to 20th	Night	16% 11% 38% 27% 8%	563
	21st to end	Night	16% 13% 31% 31% 9%	570
May	1st to 10th	Night	14% 10% 28% 32% 15% 1	570
	11th to 20th	Night	13% 5% 28% 39% 13% 2	431
	21st to end	Night	23% 8% 23% 30% 15% 2	411
June	1st to 10th	Night	16% 8% 30% 33% 12% 1	380
	11th to 20th	Night	17% 11% 36% 26% 11%	380
	21st to end	Night	8% 5% 32% 38% 16% 1	380
July	1st to 10th	Night	7% 5% 25% 44% 18%	370
	11th to 20th	Night	9% 2 30% 43% 14% 1	368
	21st to end	Night	4 4 27% 48% 14% 2	416
August	1st to 10th	Night	9% 3 21% 48% 18% 1	464
	11th to 20th	Night	8% 3 26% 42% 21% 1	564
	21st to end	Night	8% 5% 29% 43% 15%	627
September	1st to 10th	Night	13% 4 29% 39% 14% 1	617
	11th to 20th	Night	13% 6% 26% 36% 18% 2	760
	21st to end	Night	13% 9% 34% 31% 12% 1	760
October	1st to 10th	Night	14% 8% 32% 30% 14% 1	760
	11th to 20th	Night	13% 13% 36% 27% 10% 1	760
	21st to end	Night	11% 16% 42% 24% 7%	836
November	1st to 10th	Night	17% 17% 40% 23% 3	894
	11th to 20th	Night	11% 18% 46% 19% 6%	950
	21st to end	Night	8% 16% 44% 24% 6% 1	950
December	1st to 10th	Night	9% 16% 40% 25% 9% 1	950
	11th to 20th	Night	7% 16% 44% 25% 7% 1	950
	21st to end	Night	11% 15% 42% 24% 7% 1	1045

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