Ridgeway
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Ridgeway clear sky chart from 2005-11-06 to 2024-11-04.

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	14% 6% 2 6% 4 4 5% 4 6% 8% 42%	101181
	Night	15% 6% 2 6% 4 4 4 4 5% 7% 44%	97791
Transparency	Day	21% 48% 7% 13% 9% 3	104831
	Night	21% 48% 6% 12% 10% 3	102280
Seeing	Day	17% 10% 25% 25% 17% 7%	15360
	Night	17% 7% 25% 31% 18% 2	25440

By Month

Percentage Cloud Cover SE (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	18% 5% 1 3 2 3 3 3 4 6% 50%	2836
	11th to 20th	Day	15% 6% 2 6% 3 3 4 3 4 6% 50%	2840
	21st to end	Day	23% 8% 2 6% 4 3 3 2 3 4 42%	3124
February	1st to 10th	Day	13% 7% 2 6% 4 4 4 4 5% 6% 44%	1710
	11th to 20th	Day	19% 6% 2 5% 3 3 4 4 6% 6% 43%	1707
	21st to end	Day	20% 7% 2 6% 5% 4 3 3 5% 6% 40%	1665
March	1st to 10th	Day	24% 7% 2 5% 3 3 4 3 5% 7% 38%	3435
	11th to 20th	Day	11% 5% 2 4 3 3 4 4 5% 7% 54%	3480
	21st to end	Day	19% 8% 2 6% 3 3 3 3 5% 6% 41%	3815
April	1st to 10th	Day	10% 4 1 4 5% 3 3 4 7% 7% 51%	2161
	11th to 20th	Day	13% 5% 2 6% 4 3 3 3 6% 8% 48%	2254
	21st to end	Day	15% 6% 2 6% 5% 4 4 4 4 6% 43%	2370
May	1st to 10th	Day	14% 7% 3 7% 6% 5% 6% 5% 7% 9% 32%	4082
	11th to 20th	Day	19% 7% 3 7% 5% 5% 4 4 6% 8% 32%	4081
	21st to end	Day	8% 4 2 6% 4 4 5% 4 8% 10% 44%	4476
June	1st to 10th	Day	10% 4 2 5% 6% 5% 6% 5% 7% 10% 41%	2470
	11th to 20th	Day	8% 5% 2 6% 4 5% 6% 5% 8% 10% 40%	2470
	21st to end	Day	8% 5% 2 6% 5% 6% 6% 6% 7% 10% 40%	2470
July	1st to 10th	Day	7% 4 2 7% 5% 5% 7% 5% 8% 11% 37%	4120
	11th to 20th	Day	8% 6% 2 7% 5% 5% 6% 5% 8% 14% 33%	4120
	21st to end	Day	13% 8% 3 8% 6% 7% 6% 5% 8% 9% 27%	4466
August	1st to 10th	Day	15% 7% 2 8% 5% 5% 6% 5% 8% 11% 28%	4104
	11th to 20th	Day	8% 5% 2 7% 6% 5% 7% 6% 8% 11% 35%	4044
	21st to end	Day	7% 4 2 5% 3 4 4 4 6% 11% 50%	4181
September	1st to 10th	Day	12% 4 2 5% 4 4 4 3 6% 7% 48%	2252
	11th to 20th	Day	16% 5% 2 6% 3 5% 5% 4 6% 8% 41%	2090
	21st to end	Day	23% 7% 2 6% 4 3 4 3 5% 6% 37%	2090
October	1st to 10th	Day	15% 5% 2 5% 3 2 4 3 4 6% 52%	1906
	11th to 20th	Day	15% 3 2 5% 3 3 3 3 4 6% 54%	1900
	21st to end	Day	14% 5% 2 5% 2 2 2 3 3 5% 56%	2090
November	1st to 10th	Day	15% 5% 2 3 3 3 3 3 3 6% 54%	1887
	11th to 20th	Day	14% 4 2 5% 3 2 3 3 4 6% 53%	1788
	21st to end	Day	14% 4 1 5% 3 4 4 3 5% 7% 50%	1710
December	1st to 10th	Day	17% 8% 2 5% 4 4 5% 4 5% 7% 39%	1710
	11th to 20th	Day	16% 4 1 3 3 2 4 3 4 6% 54%	2153
	21st to end	Day	19% 5% 2 5% 3 4 5% 4 6% 7% 40%	3124
January	1st to 10th	Night	15% 6% 2 5% 4 4 4 3 4 5% 49%	4109
	11th to 20th	Night	15% 7% 3 6% 3 3 3 3 5% 5% 47%	4120
	21st to end	Night	24% 7% 2 4 3 3 3 3 4 4 43%	4532
February	1st to 10th	Night	16% 6% 2 5% 4 3 4 4 5% 5% 44%	2470
	11th to 20th	Night	19% 6% 2 5% 3 3 3 3 4 5% 45%	2356
	21st to end	Night	16% 7% 2 6% 4 4 4 4 5% 6% 42%	1788
March	1st to 10th	Night	22% 7% 3 6% 4 4 4 3 5% 6% 36%	3418
	11th to 20th	Night	11% 5% 2 5% 4 3 4 3 4 6% 54%	3480
	21st to end	Night	18% 5% 2 5% 3 3 3 3 4 6% 47%	3817
April	1st to 10th	Night	13% 7% 3 4 5% 4 4 3 5% 6% 46%	2018
	11th to 20th	Night	13% 5% 2 4 4 4 3 3 4 8% 48%	1875
	21st to end	Night	15% 5% 1 5% 4 4 4 4 5% 7% 47%	1825
May	1st to 10th	Night	15% 7% 2 8% 4 4 4 3 5% 8% 41%	2813
	11th to 20th	Night	20% 7% 3 6% 5% 3 4 3 5% 6% 39%	2812
	21st to end	Night	10% 4 2 5% 4 3 4 4 7% 11% 46%	3079
June	1st to 10th	Night	10% 5% 2 5% 4 5% 5% 5% 8% 12% 41%	1710
	11th to 20th	Night	10% 5% 2 5% 4 4 5% 3 8% 11% 44%	1710
	21st to end	Night	8% 5% 1 5% 5% 5% 5% 5% 8% 12% 43%	1710
July	1st to 10th	Night	6% 6% 2 8% 7% 7% 5% 5% 8% 9% 36%	2840
	11th to 20th	Night	8% 6% 2 7% 6% 5% 6% 5% 8% 10% 37%	2840
	21st to end	Night	14% 8% 4 8% 5% 5% 5% 5% 8% 9% 29%	3087
August	1st to 10th	Night	17% 8% 3 6% 5% 5% 5% 6% 7% 11% 26%	2825
	11th to 20th	Night	7% 6% 2 7% 5% 5% 6% 5% 9% 10% 38%	2785
	21st to end	Night	6% 4 2 6% 5% 4 5% 4 6% 9% 50%	3441
September	1st to 10th	Night	12% 6% 2 5% 4 3 5% 4 6% 8% 45%	1924
	11th to 20th	Night	15% 6% 2 7% 4 4 5% 4 5% 7% 40%	2090
	21st to end	Night	22% 8% 3 6% 3 4 4 3 5% 4 38%	2090
October	1st to 10th	Night	15% 6% 1 5% 4 3 4 3 4 6% 48%	2272
	11th to 20th	Night	14% 5% 2 4 3 3 3 3 4 5% 54%	2280
	21st to end	Night	13% 4 2 4 3 3 3 2 4 5% 56%	2508
November	1st to 10th	Night	15% 5% 2 4 3 2 3 2 3 5% 54%	2264
	11th to 20th	Night	13% 5% 2 4 4 3 3 3 5% 6% 53%	2389
	21st to end	Night	15% 4 1 5% 3 3 4 3 5% 6% 51%	2470
December	1st to 10th	Night	19% 6% 2 6% 4 3 3 3 5% 6% 42%	2470
	11th to 20th	Night	16% 6% 2 5% 3 3 3 3 4 5% 48%	3042
	21st to end	Night	21% 5% 2 5% 4 4 4 4 6% 7% 39%	4532

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	20% 38% 3 19% 14% 6%	2837
	11th to 20th	Day	21% 37% 4 13% 20% 4	2840
	21st to end	Day	32% 40% 4 10% 12% 2	3124
February	1st to 10th	Day	15% 65% 4 7% 7% 1	1710
	11th to 20th	Day	16% 64% 2 8% 8% 2	1716
	21st to end	Day	17% 66% 3 5% 7% 2	1665
March	1st to 10th	Day	33% 42% 6% 9% 4 6%	3435
	11th to 20th	Day	13% 41% 5% 14% 18% 9%	3480
	21st to end	Day	25% 40% 5% 13% 14% 2	3815
April	1st to 10th	Day	13% 66% 4 8% 8% 2	2161
	11th to 20th	Day	15% 65% 4 9% 6% 2	2254
	21st to end	Day	14% 65% 5% 10% 5% 1	2370
May	1st to 10th	Day	29% 44% 10% 12% 5% 1	4120
	11th to 20th	Day	30% 42% 6% 17% 5%	4085
	21st to end	Day	16% 42% 12% 13% 13% 3	4489
June	1st to 10th	Day	13% 67% 6% 9% 5% 1	2470
	11th to 20th	Day	11% 68% 6% 8% 7%	2470
	21st to end	Day	15% 65% 6% 9% 5%	2470
July	1st to 10th	Day	23% 44% 14% 11% 6% 3	4055
	11th to 20th	Day	25% 39% 14% 19% 3	4051
	21st to end	Day	37% 40% 6% 11% 6%	4324
August	1st to 10th	Day	33% 40% 12% 12% 2	4091
	11th to 20th	Day	21% 41% 14% 17% 6% 1	4083
	21st to end	Day	13% 39% 12% 25% 11% 1	4181
September	1st to 10th	Day	14% 61% 7% 9% 7% 1	2252
	11th to 20th	Day	18% 60% 5% 8% 8% 1	2090
	21st to end	Day	23% 61% 6% 7% 4	2090
October	1st to 10th	Day	20% 38% 5% 11% 20% 8%	3166
	11th to 20th	Day	10% 37% 3 14% 21% 16%	3140
	21st to end	Day	12% 37% 6% 17% 15% 12%	3428
November	1st to 10th	Day	18% 57% 3 9% 9% 3	1887
	11th to 20th	Day	14% 60% 2 9% 12% 3	1788
	21st to end	Day	13% 60% 5% 10% 11% 1	1710
December	1st to 10th	Day	21% 60% 3 8% 6% 2	1710
	11th to 20th	Day	14% 47% 3 12% 16% 7%	2150
	21st to end	Day	26% 39% 8% 15% 10% 1	3124
January	1st to 10th	Night	23% 39% 4 14% 17% 4	4109
	11th to 20th	Night	23% 38% 4 10% 21% 4	4120
	21st to end	Night	30% 40% 4 13% 9% 5%	4532
February	1st to 10th	Night	15% 66% 4 7% 7% 1	2470
	11th to 20th	Night	17% 64% 3 7% 8% 2	2358
	21st to end	Night	15% 65% 3 9% 5% 3	1788
March	1st to 10th	Night	36% 43% 6% 7% 6% 2	3418
	11th to 20th	Night	14% 42% 3 10% 19% 12%	3480
	21st to end	Night	23% 40% 5% 16% 13% 4	3817
April	1st to 10th	Night	15% 65% 3 7% 9% 1	2018
	11th to 20th	Night	14% 66% 4 8% 6% 1	1875
	21st to end	Night	12% 66% 6% 9% 7% 1	1825
May	1st to 10th	Night	28% 42% 10% 14% 5% 1	2840
	11th to 20th	Night	29% 42% 5% 14% 10%	2813
	21st to end	Night	15% 43% 12% 18% 9% 3	3087
June	1st to 10th	Night	12% 68% 6% 9% 5% 1	1710
	11th to 20th	Night	8% 67% 8% 10% 6% 1	1710
	21st to end	Night	13% 66% 6% 9% 6% 1	1710
July	1st to 10th	Night	29% 44% 9% 11% 7%	2795
	11th to 20th	Night	26% 39% 17% 14% 3	2786
	21st to end	Night	37% 38% 9% 11% 5%	2988
August	1st to 10th	Night	36% 40% 12% 10% 2	2814
	11th to 20th	Night	20% 42% 14% 18% 6%	2812
	21st to end	Night	16% 38% 8% 27% 10% 1	3441
September	1st to 10th	Night	15% 61% 7% 10% 5% 2	1924
	11th to 20th	Night	18% 62% 6% 7% 7% 1	2090
	21st to end	Night	24% 60% 5% 8% 2	2090
October	1st to 10th	Night	25% 37% 6% 10% 16% 6%	3792
	11th to 20th	Night	10% 36% 3 15% 23% 13%	3779
	21st to end	Night	11% 37% 3 19% 18% 11%	4120
November	1st to 10th	Night	18% 57% 4 9% 9% 3	2264
	11th to 20th	Night	13% 60% 3 8% 12% 6%	2389
	21st to end	Night	13% 60% 4 10% 11% 2	2470
December	1st to 10th	Night	21% 60% 3 10% 5% 2	2470
	11th to 20th	Night	18% 49% 3 11% 13% 6%	3044
	21st to end	Night	25% 40% 7% 15% 12% 1	4532

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% 23% 34% 14% 4 1	270
	11th to 20th	Day	27% 19% 37% 14% 3	270
	21st to end	Day	26% 19% 37% 15% 2	297
February	1st to 10th	Day	18% 21% 40% 16% 5%	270
	11th to 20th	Day	32% 24% 33% 9% 2	270
	21st to end	Day	27% 20% 33% 18% 3	320
March	1st to 10th	Day	22% 15% 35% 21% 7% 1	460
	11th to 20th	Day	22% 17% 35% 20% 5% 1	460
	21st to end	Day	23% 15% 35% 21% 6%	506
April	1st to 10th	Day	20% 16% 34% 21% 7% 1	460
	11th to 20th	Day	17% 17% 27% 23% 12% 3	452
	21st to end	Day	19% 12% 32% 24% 11% 2	460
May	1st to 10th	Day	19% 14% 32% 23% 9% 4	463
	11th to 20th	Day	17% 6% 24% 25% 20% 8%	487
	21st to end	Day	15% 4 19% 29% 22% 10%	529
June	1st to 10th	Day	11% 4 22% 31% 21% 10%	490
	11th to 20th	Day	10% 4 20% 29% 23% 14%	490
	21st to end	Day	10% 5% 16% 36% 25% 8%	490
July	1st to 10th	Day	12% 2 13% 27% 34% 12%	485
	11th to 20th	Day	6% 2 11% 30% 35% 15%	484
	21st to end	Day	9% 3 12% 34% 26% 16%	532
August	1st to 10th	Day	14% 3 17% 25% 26% 15%	486
	11th to 20th	Day	10% 3 12% 31% 27% 17%	479
	21st to end	Day	10% 3 10% 30% 27% 20%	539
September	1st to 10th	Day	15% 3 17% 21% 26% 19%	490
	11th to 20th	Day	17% 3 13% 27% 26% 15%	490
	21st to end	Day	29% 7% 19% 24% 17% 3	490
October	1st to 10th	Day	19% 6% 20% 29% 20% 6%	490
	11th to 20th	Day	13% 9% 25% 27% 22% 4	490
	21st to end	Day	15% 9% 27% 32% 14% 3	539
November	1st to 10th	Day	20% 9% 26% 26% 16% 3	467
	11th to 20th	Day	17% 16% 29% 25% 12% 1	348
	21st to end	Day	14% 18% 30% 25% 12% 1	270
December	1st to 10th	Day	23% 14% 40% 17% 5% 1	270
	11th to 20th	Day	19% 14% 37% 23% 6% 1	270
	21st to end	Day	28% 12% 32% 17% 9% 1	297
January	1st to 10th	Night	19% 13% 36% 27% 5% 1	760
	11th to 20th	Night	19% 12% 36% 29% 4	760
	21st to end	Night	21% 10% 39% 28% 2	836
February	1st to 10th	Night	20% 13% 34% 30% 3	760
	11th to 20th	Night	24% 14% 39% 21% 2	743
	21st to end	Night	19% 13% 39% 25% 3	628
March	1st to 10th	Night	18% 14% 34% 29% 5%	760
	11th to 20th	Night	20% 13% 35% 25% 7% 1	760
	21st to end	Night	20% 10% 38% 27% 5%	836
April	1st to 10th	Night	17% 16% 34% 26% 7%	760
	11th to 20th	Night	16% 11% 34% 27% 12% 1	751
	21st to end	Night	17% 6% 34% 33% 10%	685
May	1st to 10th	Night	12% 8% 32% 34% 14% 1	570
	11th to 20th	Night	17% 4 24% 33% 20% 1	561
	21st to end	Night	16% 2 11% 35% 32% 4	617
June	1st to 10th	Night	11% 3 15% 39% 30% 3	570
	11th to 20th	Night	12% 2 14% 32% 37% 4	570
	21st to end	Night	9% 2 14% 37% 34% 2	570
July	1st to 10th	Night	10% 2 8% 32% 43% 5%	555
	11th to 20th	Night	5% 2 8% 32% 47% 7%	552
	21st to end	Night	10% 1 10% 39% 36% 4	624
August	1st to 10th	Night	15% 2 7% 34% 36% 6%	567
	11th to 20th	Night	11% 2 8% 32% 42% 4	564
	21st to end	Night	11% 2 8% 32% 39% 8%	814
September	1st to 10th	Night	14% 2 9% 31% 36% 8%	760
	11th to 20th	Night	16% 3 12% 30% 34% 5%	760
	21st to end	Night	25% 4 16% 32% 22% 2	760
October	1st to 10th	Night	18% 5% 19% 28% 25% 5%	760
	11th to 20th	Night	15% 6% 25% 34% 18% 2	760
	21st to end	Night	16% 7% 25% 35% 16% 1	836
November	1st to 10th	Night	17% 7% 24% 35% 15% 2	755
	11th to 20th	Night	15% 9% 30% 34% 11%	760
	21st to end	Night	17% 6% 32% 33% 11% 1	760
December	1st to 10th	Night	21% 10% 32% 30% 7%	760
	11th to 20th	Night	18% 8% 33% 35% 6%	760
	21st to end	Night	25% 11% 27% 31% 6%	836

Page generated at 2024-11-01 22:47:47. Version ac07

Copyright © 2024 Attilla Danko.