Sideroad 10D
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Sideroad 10D clear sky chart from 2005-11-06 to 2024-11-05.

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% 12% 5% 10% 6% 5% 5% 4 5% 6% 29%	101719
	Night	13% 13% 5% 11% 6% 5% 4 3 5% 6% 28%	97322
Transparency	Day	54% 6% 10% 19% 10% 1	105291
	Night	57% 6% 11% 17% 9% 1	101839
Seeing	Day	19% 17% 30% 22% 10% 3	15051
	Night	20% 16% 30% 24% 9% 1	24136

By Month

Percentage Cloud Cover NE (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	12% 18% 11% 20% 11% 5% 4 3 3 3 8%	2208
	11th to 20th	Day	8% 18% 10% 25% 13% 9% 4 3 4 3 4	2754
	21st to end	Day	14% 21% 9% 19% 8% 5% 5% 3 3 3 8%	3124
February	1st to 10th	Day	12% 17% 8% 19% 10% 6% 5% 3 4 4 11%	1710
	11th to 20th	Day	11% 14% 8% 21% 10% 6% 5% 4 4 5% 13%	1663
	21st to end	Day	12% 19% 7% 15% 8% 6% 4 3 4 4 17%	1498
March	1st to 10th	Day	13% 15% 6% 12% 7% 5% 4 3 4 5% 26%	3385
	11th to 20th	Day	9% 16% 12% 15% 6% 4 4 3 4 4 23%	3480
	21st to end	Day	13% 14% 7% 10% 5% 4 5% 4 4 6% 28%	3815
April	1st to 10th	Day	16% 17% 5% 10% 5% 4 5% 3 5% 6% 25%	2204
	11th to 20th	Day	17% 14% 3 7% 4 4 3 3 4 5% 35%	2406
	21st to end	Day	19% 13% 4 7% 4 4 3 3 5% 5% 32%	2470
May	1st to 10th	Day	15% 11% 3 8% 4 4 4 3 5% 7% 36%	4108
	11th to 20th	Day	16% 10% 3 7% 5% 4 5% 4 6% 7% 33%	4302
	21st to end	Day	13% 7% 2 6% 4 4 4 3 5% 7% 44%	4837
June	1st to 10th	Day	16% 9% 3 6% 4 4 5% 4 6% 9% 35%	2706
	11th to 20th	Day	12% 7% 2 5% 4 4 5% 5% 7% 9% 39%	2850
	21st to end	Day	17% 7% 2 6% 5% 4 5% 4 5% 7% 37%	2850
July	1st to 10th	Day	14% 6% 3 7% 6% 6% 6% 5% 7% 8% 33%	4760
	11th to 20th	Day	12% 6% 3 5% 5% 4 4 4 6% 8% 43%	4577
	21st to end	Day	11% 6% 2 6% 4 5% 4 4 6% 8% 43%	4466
August	1st to 10th	Day	13% 7% 3 7% 4 4 6% 4 6% 8% 37%	4104
	11th to 20th	Day	16% 7% 3 7% 5% 5% 5% 4 6% 8% 33%	4044
	21st to end	Day	11% 6% 2 6% 4 5% 5% 4 6% 9% 42%	4447
September	1st to 10th	Day	16% 8% 2 8% 4 4 5% 3 5% 7% 38%	2280
	11th to 20th	Day	15% 6% 2 6% 4 5% 4 4 6% 8% 41%	2104
	21st to end	Day	16% 8% 3 10% 5% 6% 4 4 5% 7% 33%	2090
October	1st to 10th	Day	20% 11% 3 7% 5% 4 4 3 5% 7% 31%	1901
	11th to 20th	Day	19% 16% 4 10% 6% 6% 5% 3 5% 5% 22%	1900
	21st to end	Day	25% 20% 3 9% 4 4 4 3 6% 4 17%	2058
November	1st to 10th	Day	14% 21% 4 9% 5% 4 5% 4 4 6% 24%	1637
	11th to 20th	Day	13% 19% 6% 12% 7% 6% 6% 3 5% 7% 17%	1520
	21st to end	Day	15% 21% 7% 14% 7% 6% 5% 4 4 6% 12%	1520
December	1st to 10th	Day	12% 24% 11% 20% 6% 5% 3 4 3 4 8%	1520
	11th to 20th	Day	15% 19% 9% 19% 8% 5% 4 3 3 4 11%	1906
	21st to end	Day	19% 22% 8% 17% 6% 5% 4 3 3 4 8%	2515
January	1st to 10th	Night	11% 21% 10% 20% 10% 5% 5% 3 4 3 7%	4748
	11th to 20th	Night	11% 13% 10% 25% 12% 8% 4 3 4 3 6%	4200
	21st to end	Night	14% 17% 9% 19% 11% 7% 5% 3 4 3 8%	4532
February	1st to 10th	Night	10% 18% 8% 17% 10% 7% 6% 4 4 4 13%	2470
	11th to 20th	Night	10% 15% 8% 17% 9% 7% 5% 4 4 5% 16%	2403
	21st to end	Night	12% 14% 6% 15% 9% 6% 6% 4 5% 5% 20%	1953
March	1st to 10th	Night	11% 15% 6% 9% 5% 4 5% 4 4 7% 30%	3453
	11th to 20th	Night	9% 16% 7% 11% 5% 4 4 3 5% 6% 29%	3479
	21st to end	Night	11% 12% 5% 11% 6% 5% 5% 4 5% 6% 31%	3817
April	1st to 10th	Night	17% 14% 4 9% 5% 3 4 3 5% 6% 29%	1974
	11th to 20th	Night	16% 12% 4 8% 4 4 3 3 3 7% 36%	1739
	21st to end	Night	16% 14% 4 9% 5% 4 4 3 5% 6% 31%	1710
May	1st to 10th	Night	13% 8% 2 7% 4 5% 4 3 6% 7% 40%	2833
	11th to 20th	Night	15% 8% 2 5% 4 4 5% 3 5% 7% 42%	2577
	21st to end	Night	10% 7% 2 6% 3 4 4 3 5% 7% 49%	2738
June	1st to 10th	Night	15% 7% 3 6% 4 5% 5% 4 5% 8% 38%	1470
	11th to 20th	Night	11% 5% 2 5% 5% 5% 5% 5% 6% 10% 42%	1330
	21st to end	Night	14% 7% 2 5% 4 4 4 4 5% 8% 42%	1330
July	1st to 10th	Night	9% 7% 3 6% 4 3 4 3 5% 8% 47%	2210
	11th to 20th	Night	13% 5% 1 5% 3 3 3 3 4 7% 52%	2379
	21st to end	Night	8% 7% 2 5% 5% 4 5% 4 7% 8% 47%	3087
August	1st to 10th	Night	10% 7% 3 6% 4 4 5% 3 6% 6% 45%	2825
	11th to 20th	Night	14% 6% 3 6% 4 4 4 4 5% 8% 41%	2785
	21st to end	Night	14% 6% 1 6% 4 4 5% 3 5% 7% 45%	3176
September	1st to 10th	Night	13% 5% 2 6% 4 4 4 4 6% 8% 46%	1900
	11th to 20th	Night	13% 6% 2 4 3 3 4 3 6% 7% 49%	2073
	21st to end	Night	18% 9% 2 7% 4 4 5% 3 4 7% 37%	2090
October	1st to 10th	Night	19% 8% 3 7% 4 5% 4 3 4 7% 36%	2278
	11th to 20th	Night	20% 14% 3 9% 5% 5% 4 3 5% 6% 26%	2280
	21st to end	Night	20% 19% 4 8% 6% 5% 4 3 5% 6% 20%	2536
November	1st to 10th	Night	16% 20% 4 9% 5% 4 4 3 4 5% 26%	2539
	11th to 20th	Night	14% 18% 5% 12% 6% 5% 5% 3 6% 6% 19%	2660
	21st to end	Night	16% 18% 9% 12% 6% 5% 5% 3 5% 5% 15%	2660
December	1st to 10th	Night	15% 23% 9% 16% 6% 5% 5% 3 4 4 11%	2660
	11th to 20th	Night	10% 20% 10% 19% 9% 6% 5% 4 4 3 11%	3288
	21st to end	Night	19% 20% 9% 20% 7% 5% 4 3 3 3 7%	5140

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	81% 5% 8% 5%	2209
	11th to 20th	Day	85% 6% 3 4 2	2754
	21st to end	Day	81% 4 8% 5% 2	3124
February	1st to 10th	Day	76% 6% 6% 9% 2	1710
	11th to 20th	Day	73% 5% 7% 9% 5% 1	1672
	21st to end	Day	71% 6% 7% 11% 5%	1498
March	1st to 10th	Day	62% 5% 11% 14% 9% 1	3388
	11th to 20th	Day	63% 5% 7% 17% 6% 1	3480
	21st to end	Day	55% 6% 11% 17% 9% 2	3815
April	1st to 10th	Day	61% 5% 8% 17% 8% 1	2204
	11th to 20th	Day	52% 5% 8% 20% 15% 1	2406
	21st to end	Day	54% 6% 9% 18% 12% 2	2470
May	1st to 10th	Day	46% 7% 10% 21% 15% 1	4120
	11th to 20th	Day	48% 8% 12% 22% 9% 1	4306
	21st to end	Day	40% 5% 12% 21% 18% 4	4837
June	1st to 10th	Day	45% 7% 11% 21% 15% 1	2706
	11th to 20th	Day	39% 8% 11% 24% 17% 1	2850
	21st to end	Day	44% 7% 12% 24% 13% 1	2850
July	1st to 10th	Day	46% 7% 13% 19% 14% 1	4686
	11th to 20th	Day	36% 7% 12% 33% 11% 1	4496
	21st to end	Day	38% 7% 10% 25% 18% 1	4324
August	1st to 10th	Day	44% 8% 13% 23% 12% 1	4091
	11th to 20th	Day	47% 8% 15% 22% 8%	4083
	21st to end	Day	38% 7% 12% 31% 10% 1	4447
September	1st to 10th	Day	46% 6% 12% 24% 10% 2	2280
	11th to 20th	Day	41% 5% 14% 28% 13% 1	2104
	21st to end	Day	51% 7% 11% 23% 8% 1	2090
October	1st to 10th	Day	47% 6% 12% 23% 11% 1	3161
	11th to 20th	Day	55% 5% 10% 18% 12% 1	3140
	21st to end	Day	63% 6% 11% 16% 4	3372
November	1st to 10th	Day	62% 6% 11% 15% 6%	1637
	11th to 20th	Day	67% 7% 10% 10% 5%	1520
	21st to end	Day	74% 6% 9% 9% 1	1520
December	1st to 10th	Day	81% 6% 7% 5% 1	1520
	11th to 20th	Day	79% 5% 9% 7% 1	1906
	21st to end	Day	83% 4 6% 5% 1	2515
January	1st to 10th	Night	83% 5% 7% 5% 1	4748
	11th to 20th	Night	84% 7% 5% 3 1	4200
	21st to end	Night	81% 4 9% 4 2	4532
February	1st to 10th	Night	74% 6% 7% 10% 2	2470
	11th to 20th	Night	70% 6% 9% 12% 4	2405
	21st to end	Night	64% 8% 9% 12% 7%	1953
March	1st to 10th	Night	54% 7% 12% 19% 8% 1	3463
	11th to 20th	Night	53% 8% 11% 17% 8% 1	3480
	21st to end	Night	53% 5% 9% 22% 9% 1	3817
April	1st to 10th	Night	57% 4 7% 20% 11%	1974
	11th to 20th	Night	50% 5% 8% 20% 17% 1	1739
	21st to end	Night	54% 5% 8% 15% 16% 2	1710
May	1st to 10th	Night	43% 5% 13% 20% 14% 5%	2840
	11th to 20th	Night	42% 6% 13% 25% 12% 2	2578
	21st to end	Night	34% 6% 13% 24% 20% 2	2739
June	1st to 10th	Night	44% 5% 12% 20% 17% 2	1470
	11th to 20th	Night	37% 7% 12% 26% 18% 1	1330
	21st to end	Night	40% 5% 14% 26% 14% 1	1330
July	1st to 10th	Night	36% 5% 14% 23% 18% 4	2175
	11th to 20th	Night	33% 5% 12% 34% 15% 1	2337
	21st to end	Night	33% 8% 13% 28% 16% 1	2988
August	1st to 10th	Night	38% 6% 12% 28% 15% 1	2814
	11th to 20th	Night	40% 7% 16% 23% 13% 1	2812
	21st to end	Night	38% 7% 13% 30% 12% 1	3176
September	1st to 10th	Night	34% 8% 14% 29% 13% 1	1900
	11th to 20th	Night	34% 5% 15% 28% 17% 1	2073
	21st to end	Night	47% 7% 12% 25% 9% 1	2090
October	1st to 10th	Night	42% 6% 10% 24% 17% 1	3798
	11th to 20th	Night	51% 5% 12% 18% 14%	3779
	21st to end	Night	55% 7% 13% 19% 5%	4172
November	1st to 10th	Night	61% 5% 10% 17% 6% 1	2539
	11th to 20th	Night	65% 6% 13% 12% 4 2	2660
	21st to end	Night	71% 7% 12% 8% 2	2660
December	1st to 10th	Night	77% 7% 9% 5% 2	2660
	11th to 20th	Night	77% 5% 10% 7% 1	3288
	21st to end	Night	85% 4 5% 5% 1	5140

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	17% 29% 33% 15% 5% 1	180
	11th to 20th	Day	16% 32% 36% 12% 3	263
	21st to end	Day	23% 22% 34% 19% 2	297
February	1st to 10th	Day	23% 31% 33% 10% 2	270
	11th to 20th	Day	20% 30% 39% 9% 2	270
	21st to end	Day	25% 32% 34% 9%	225
March	1st to 10th	Day	20% 23% 37% 16% 4	424
	11th to 20th	Day	19% 22% 38% 17% 4	460
	21st to end	Day	26% 16% 33% 18% 6%	506
April	1st to 10th	Day	23% 21% 34% 17% 5%	460
	11th to 20th	Day	28% 21% 24% 14% 8% 4	452
	21st to end	Day	27% 16% 29% 20% 7% 1	460
May	1st to 10th	Day	20% 16% 32% 22% 9% 2	463
	11th to 20th	Day	19% 9% 30% 25% 14% 3	487
	21st to end	Day	17% 11% 27% 27% 14% 3	529
June	1st to 10th	Day	18% 14% 28% 28% 12% 1	536
	11th to 20th	Day	14% 12% 32% 29% 10% 3	680
	21st to end	Day	20% 9% 31% 27% 10% 3	680
July	1st to 10th	Day	13% 10% 27% 31% 17% 3	671
	11th to 20th	Day	13% 10% 29% 29% 13% 6%	578
	21st to end	Day	10% 6% 31% 32% 17% 4	532
August	1st to 10th	Day	13% 8% 24% 32% 15% 7%	486
	11th to 20th	Day	15% 6% 21% 30% 19% 8%	479
	21st to end	Day	14% 11% 25% 30% 16% 5%	539
September	1st to 10th	Day	16% 13% 25% 25% 16% 6%	490
	11th to 20th	Day	13% 8% 23% 27% 20% 9%	490
	21st to end	Day	15% 15% 28% 24% 14% 4	490
October	1st to 10th	Day	24% 16% 24% 20% 12% 3	490
	11th to 20th	Day	24% 24% 32% 16% 4	490
	21st to end	Day	33% 26% 25% 13% 3	507
November	1st to 10th	Day	24% 26% 31% 13% 5%	249
	11th to 20th	Day	24% 29% 33% 11% 2 1	180
	21st to end	Day	23% 29% 38% 9% 1	180
December	1st to 10th	Day	21% 35% 32% 12% 1	180
	11th to 20th	Day	21% 37% 31% 9% 2	180
	21st to end	Day	26% 34% 32% 6% 2	198
January	1st to 10th	Night	20% 28% 33% 16% 4	950
	11th to 20th	Night	22% 24% 33% 17% 4 1	786
	21st to end	Night	15% 18% 40% 21% 5% 1	836
February	1st to 10th	Night	19% 26% 35% 19% 2	760
	11th to 20th	Night	18% 21% 36% 20% 4	743
	21st to end	Night	21% 24% 33% 18% 3	628
March	1st to 10th	Night	17% 20% 37% 20% 5%	760
	11th to 20th	Night	17% 21% 37% 19% 4 1	760
	21st to end	Night	19% 16% 31% 26% 7% 1	836
April	1st to 10th	Night	23% 17% 33% 24% 3	760
	11th to 20th	Night	21% 15% 31% 23% 9% 1	615
	21st to end	Night	23% 14% 28% 25% 11%	570
May	1st to 10th	Night	19% 8% 28% 33% 12% 2	570
	11th to 20th	Night	18% 8% 27% 35% 11% 1	430
	21st to end	Night	13% 6% 27% 39% 15%	411
June	1st to 10th	Night	17% 8% 29% 34% 10% 1	380
	11th to 20th	Night	11% 10% 23% 40% 16%	380
	21st to end	Night	18% 6% 24% 35% 17% 1	380
July	1st to 10th	Night	9% 5% 19% 47% 19% 1	370
	11th to 20th	Night	10% 5% 28% 34% 21% 1	379
	21st to end	Night	10% 4 24% 42% 19% 1	624
August	1st to 10th	Night	12% 5% 21% 36% 25% 1	567
	11th to 20th	Night	10% 5% 19% 36% 26% 4	564
	21st to end	Night	16% 6% 23% 30% 23% 2	653
September	1st to 10th	Night	14% 8% 25% 32% 17% 5%	760
	11th to 20th	Night	16% 6% 21% 35% 18% 4	760
	21st to end	Night	19% 11% 22% 30% 14% 4	760
October	1st to 10th	Night	24% 10% 29% 22% 13% 1	760
	11th to 20th	Night	27% 18% 27% 21% 6% 1	760
	21st to end	Night	32% 20% 28% 16% 3	836
November	1st to 10th	Night	28% 17% 31% 17% 7%	760
	11th to 20th	Night	22% 28% 29% 16% 4 1	760
	21st to end	Night	24% 24% 34% 16% 2	760
December	1st to 10th	Night	26% 25% 33% 12% 3	760
	11th to 20th	Night	21% 27% 36% 13% 2 1	760
	21st to end	Night	27% 25% 34% 13% 1	988

Page generated at 2024-11-03 02:11:13. Version ac07

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