Transit Dreams North
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Transit Dreams North clear sky chart from 2005-11-06 to 2024-12-09.

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	18% 13% 4 8% 5% 4 4 4 5% 6% 29%	101699
	Night	18% 16% 5% 9% 5% 4 4 3 4 5% 26%	98059
Transparency	Day	54% 7% 12% 18% 9% 1	105304
	Night	58% 6% 11% 16% 8% 1	102542
Seeing	Day	26% 17% 28% 18% 8% 2	14632
	Night	27% 16% 27% 21% 8% 1	24090

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	16% 31% 12% 15% 7% 3 3 2 2 2 9%	2517
	11th to 20th	Day	11% 27% 10% 20% 7% 5% 4 2 4 3 7%	2776
	21st to end	Day	21% 22% 9% 17% 7% 5% 5% 3 2 3 7%	3124
February	1st to 10th	Day	17% 22% 7% 17% 9% 5% 4 2 3 3 12%	1710
	11th to 20th	Day	13% 21% 9% 18% 8% 3 4 3 3 4 15%	1663
	21st to end	Day	19% 19% 6% 13% 7% 4 4 3 4 5% 17%	1490
March	1st to 10th	Day	19% 16% 6% 8% 4 3 4 3 4 5% 28%	3432
	11th to 20th	Day	11% 23% 7% 9% 4 4 4 3 4 5% 27%	3480
	21st to end	Day	18% 15% 5% 10% 5% 3 4 3 5% 5% 26%	3815
April	1st to 10th	Day	19% 18% 3 6% 5% 3 4 3 4 5% 29%	2266
	11th to 20th	Day	20% 14% 2 7% 4 4 3 3 4 7% 33%	2255
	21st to end	Day	22% 13% 3 6% 4 4 4 3 4 5% 32%	2470
May	1st to 10th	Day	24% 9% 3 6% 5% 4 4 3 5% 7% 31%	4108
	11th to 20th	Day	18% 10% 3 8% 5% 5% 5% 4 6% 8% 28%	4366
	21st to end	Day	14% 7% 2 5% 4 4 4 4 5% 8% 42%	4837
June	1st to 10th	Day	18% 7% 2 6% 4 5% 5% 4 5% 7% 36%	2660
	11th to 20th	Day	16% 5% 3 5% 4 5% 5% 5% 7% 9% 36%	2660
	21st to end	Day	17% 7% 2 5% 4 4 5% 4 6% 8% 39%	2660
July	1st to 10th	Day	12% 6% 2 6% 4 4 5% 4 6% 11% 40%	4440
	11th to 20th	Day	15% 5% 2 6% 4 4 4 4 6% 9% 40%	4440
	21st to end	Day	10% 6% 2 7% 5% 5% 5% 5% 8% 8% 38%	4481
August	1st to 10th	Day	18% 6% 3 6% 4 4 4 4 6% 8% 37%	4104
	11th to 20th	Day	16% 6% 2 8% 5% 5% 6% 5% 7% 9% 28%	4044
	21st to end	Day	15% 5% 2 5% 4 4 4 4 6% 9% 41%	4276
September	1st to 10th	Day	18% 7% 3 6% 4 4 4 4 6% 8% 37%	2280
	11th to 20th	Day	16% 6% 2 5% 4 4 4 4 6% 8% 42%	2209
	21st to end	Day	19% 8% 3 8% 5% 5% 5% 4 5% 7% 31%	2024
October	1st to 10th	Day	24% 9% 3 6% 4 4 3 4 6% 7% 31%	1900
	11th to 20th	Day	25% 12% 4 8% 4 3 4 3 4 5% 28%	1900
	21st to end	Day	29% 16% 3 8% 5% 4 3 3 4 5% 20%	2090
November	1st to 10th	Day	20% 16% 4 8% 4 4 4 3 4 5% 28%	1760
	11th to 20th	Day	16% 25% 5% 9% 4 4 3 2 6% 5% 21%	1600
	21st to end	Day	21% 27% 6% 9% 5% 3 4 3 2 4 16%	1600
December	1st to 10th	Day	19% 31% 8% 12% 4 3 3 2 3 4 9%	1584
	11th to 20th	Day	19% 24% 8% 18% 5% 3 2 2 3 4 11%	1906
	21st to end	Day	23% 31% 8% 11% 5% 3 3 2 2 3 10%	2772
January	1st to 10th	Night	17% 30% 10% 15% 5% 3 3 2 3 3 9%	4429
	11th to 20th	Night	13% 27% 10% 19% 10% 5% 3 2 3 3 7%	4180
	21st to end	Night	21% 24% 10% 16% 7% 5% 3 2 2 2 8%	4532
February	1st to 10th	Night	18% 23% 7% 16% 8% 4 3 3 3 3 13%	2470
	11th to 20th	Night	16% 16% 8% 17% 8% 5% 4 3 4 4 15%	2403
	21st to end	Night	19% 18% 6% 16% 6% 4 3 2 4 5% 16%	1961
March	1st to 10th	Night	21% 15% 4 9% 5% 3 3 2 4 4 28%	3408
	11th to 20th	Night	19% 22% 6% 9% 4 3 3 3 4 4 23%	3479
	21st to end	Night	17% 12% 5% 9% 4 3 4 3 4 5% 34%	3817
April	1st to 10th	Night	21% 17% 4 7% 4 4 3 2 4 5% 29%	1914
	11th to 20th	Night	21% 11% 3 7% 4 3 3 4 4 6% 33%	1875
	21st to end	Night	20% 10% 4 6% 5% 4 5% 3 4 7% 32%	1724
May	1st to 10th	Night	26% 11% 3 6% 5% 4 4 3 5% 6% 29%	2833
	11th to 20th	Night	15% 9% 2 7% 5% 5% 5% 4 6% 8% 33%	2513
	21st to end	Night	16% 6% 1 5% 3 4 3 3 6% 8% 44%	2738
June	1st to 10th	Night	15% 7% 3 7% 6% 6% 5% 5% 5% 7% 35%	1520
	11th to 20th	Night	13% 7% 2 7% 5% 4 5% 4 6% 7% 40%	1520
	21st to end	Night	17% 7% 2 6% 5% 4 4 4 7% 7% 38%	1520
July	1st to 10th	Night	15% 7% 2 7% 4 4 4 3 6% 8% 40%	2520
	11th to 20th	Night	15% 6% 2 5% 4 3 4 4 5% 7% 43%	2520
	21st to end	Night	12% 6% 2 5% 4 4 5% 4 6% 7% 44%	3055
August	1st to 10th	Night	14% 8% 3 7% 4 4 4 4 6% 8% 38%	2825
	11th to 20th	Night	20% 7% 3 7% 4 5% 4 4 5% 6% 33%	2785
	21st to end	Night	12% 5% 2 6% 4 4 5% 4 6% 8% 43%	3346
September	1st to 10th	Night	18% 6% 3 5% 4 3 4 3 5% 7% 42%	1900
	11th to 20th	Night	15% 5% 2 4 3 3 4 3 5% 6% 48%	1967
	21st to end	Night	20% 9% 2 7% 4 4 5% 3 6% 8% 33%	2154
October	1st to 10th	Night	20% 8% 3 7% 4 5% 4 3 6% 6% 36%	2280
	11th to 20th	Night	25% 12% 3 6% 5% 4 4 3 4 6% 27%	2280
	21st to end	Night	30% 12% 3 6% 4 4 3 4 5% 5% 23%	2508
November	1st to 10th	Night	19% 15% 3 8% 4 3 4 2 4 5% 33%	2532
	11th to 20th	Night	18% 21% 4 9% 5% 4 4 3 4 6% 22%	2800
	21st to end	Night	20% 23% 7% 10% 5% 4 4 3 4 5% 16%	2800
December	1st to 10th	Night	22% 29% 8% 10% 5% 3 4 3 3 3 10%	2779
	11th to 20th	Night	18% 26% 10% 14% 5% 4 3 2 3 3 11%	3288
	21st to end	Night	25% 27% 7% 10% 5% 3 3 3 3 4 8%	4884

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	84% 4 5% 5% 2	2518
	11th to 20th	Day	81% 5% 8% 5% 2	2776
	21st to end	Day	84% 4 7% 3 1	3124
February	1st to 10th	Day	80% 4 7% 7% 2	1710
	11th to 20th	Day	74% 5% 7% 10% 4	1672
	21st to end	Day	70% 5% 10% 11% 4 1	1490
March	1st to 10th	Day	58% 5% 10% 21% 5%	3435
	11th to 20th	Day	59% 7% 16% 13% 5% 1	3480
	21st to end	Day	59% 7% 7% 19% 7% 1	3815
April	1st to 10th	Day	58% 5% 11% 15% 10%	2266
	11th to 20th	Day	51% 6% 10% 20% 10% 2	2255
	21st to end	Day	56% 6% 9% 16% 13% 1	2470
May	1st to 10th	Day	52% 6% 12% 20% 9% 2	4120
	11th to 20th	Day	52% 9% 13% 18% 7% 1	4370
	21st to end	Day	39% 8% 14% 23% 14% 3	4837
June	1st to 10th	Day	46% 8% 12% 19% 14% 1	2660
	11th to 20th	Day	43% 8% 14% 22% 12%	2660
	21st to end	Day	43% 7% 13% 23% 12% 1	2660
July	1st to 10th	Day	39% 7% 13% 26% 14% 1	4370
	11th to 20th	Day	39% 8% 15% 22% 16%	4365
	21st to end	Day	40% 9% 14% 21% 15%	4338
August	1st to 10th	Day	45% 8% 14% 22% 12% 1	4091
	11th to 20th	Day	47% 12% 15% 20% 5%	4083
	21st to end	Day	38% 8% 12% 30% 11% 1	4276
September	1st to 10th	Day	45% 7% 12% 23% 11% 1	2280
	11th to 20th	Day	39% 7% 12% 27% 14% 1	2209
	21st to end	Day	52% 7% 12% 19% 10% 1	2024
October	1st to 10th	Day	44% 7% 14% 22% 11% 1	3160
	11th to 20th	Day	49% 5% 15% 16% 12% 3	3140
	21st to end	Day	52% 6% 15% 20% 7% 1	3428
November	1st to 10th	Day	58% 6% 9% 17% 9% 2	1760
	11th to 20th	Day	64% 5% 11% 13% 5% 2	1600
	21st to end	Day	73% 5% 9% 9% 4	1600
December	1st to 10th	Day	80% 5% 6% 7% 1	1584
	11th to 20th	Day	77% 6% 9% 6% 2	1906
	21st to end	Day	82% 4 7% 6%	2772
January	1st to 10th	Night	80% 7% 7% 5% 2	4429
	11th to 20th	Night	84% 4 7% 3 1	4180
	21st to end	Night	84% 4 6% 4 2	4532
February	1st to 10th	Night	77% 5% 7% 8% 3	2470
	11th to 20th	Night	73% 5% 8% 10% 3	2405
	21st to end	Night	70% 5% 9% 10% 5%	1961
March	1st to 10th	Night	60% 5% 9% 19% 6%	3418
	11th to 20th	Night	64% 6% 11% 13% 5% 1	3480
	21st to end	Night	50% 8% 9% 20% 12% 2	3817
April	1st to 10th	Night	57% 5% 10% 18% 9%	1914
	11th to 20th	Night	52% 5% 11% 18% 12% 2	1875
	21st to end	Night	51% 6% 10% 18% 13% 2	1724
May	1st to 10th	Night	56% 6% 9% 18% 9% 3	2840
	11th to 20th	Night	46% 9% 15% 21% 7% 1	2514
	21st to end	Night	37% 7% 13% 24% 17% 3	2739
June	1st to 10th	Night	44% 9% 12% 21% 13% 1	1520
	11th to 20th	Night	41% 8% 12% 23% 15% 1	1520
	21st to end	Night	43% 8% 14% 23% 12% 2	1520
July	1st to 10th	Night	41% 6% 12% 23% 16% 2	2480
	11th to 20th	Night	38% 7% 16% 24% 15% 1	2472
	21st to end	Night	37% 8% 16% 23% 14% 2	2957
August	1st to 10th	Night	41% 8% 15% 27% 9% 1	2814
	11th to 20th	Night	49% 8% 13% 22% 7%	2812
	21st to end	Night	35% 8% 15% 30% 11% 1	3346
September	1st to 10th	Night	40% 7% 12% 25% 13% 2	1900
	11th to 20th	Night	36% 6% 13% 26% 18% 1	1967
	21st to end	Night	49% 7% 12% 20% 11% 1	2154
October	1st to 10th	Night	43% 8% 11% 22% 15% 1	3800
	11th to 20th	Night	51% 5% 12% 16% 13% 2	3779
	21st to end	Night	48% 5% 16% 21% 8% 1	4120
November	1st to 10th	Night	54% 6% 9% 19% 9% 2	2532
	11th to 20th	Night	64% 6% 10% 13% 6% 2	2800
	21st to end	Night	71% 7% 10% 10% 3	2800
December	1st to 10th	Night	80% 5% 8% 6% 2	2779
	11th to 20th	Night	78% 6% 9% 5% 2	3288
	21st to end	Night	80% 6% 8% 6%	4884

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	31% 31% 26% 8% 4 1	180
	11th to 20th	Day	36% 35% 19% 8% 2	252
	21st to end	Day	30% 28% 28% 11% 3	297
February	1st to 10th	Day	39% 27% 25% 8% 1	270
	11th to 20th	Day	32% 34% 28% 5%	270
	21st to end	Day	42% 24% 29% 6%	289
March	1st to 10th	Day	33% 21% 30% 12% 3	460
	11th to 20th	Day	31% 23% 33% 10% 3 1	460
	21st to end	Day	35% 21% 26% 14% 4	506
April	1st to 10th	Day	33% 22% 28% 12% 5%	460
	11th to 20th	Day	35% 22% 22% 11% 7% 2	452
	21st to end	Day	31% 18% 31% 16% 3 1	460
May	1st to 10th	Day	32% 16% 28% 17% 5% 2	463
	11th to 20th	Day	24% 15% 29% 23% 9% 1	487
	21st to end	Day	19% 14% 30% 23% 10% 4	529
June	1st to 10th	Day	21% 17% 35% 20% 7% 1	490
	11th to 20th	Day	18% 15% 29% 26% 10% 1	490
	21st to end	Day	22% 15% 34% 19% 8% 1	490
July	1st to 10th	Day	13% 11% 30% 26% 17% 3	485
	11th to 20th	Day	14% 12% 31% 26% 13% 4	484
	21st to end	Day	15% 10% 34% 26% 12% 3	532
August	1st to 10th	Day	15% 10% 26% 29% 15% 5%	486
	11th to 20th	Day	15% 10% 28% 25% 17% 4	479
	21st to end	Day	17% 9% 30% 26% 13% 5%	539
September	1st to 10th	Day	18% 13% 26% 23% 15% 5%	490
	11th to 20th	Day	14% 8% 22% 27% 22% 8%	490
	21st to end	Day	19% 21% 25% 20% 11% 4	490
October	1st to 10th	Day	25% 13% 27% 18% 14% 3	490
	11th to 20th	Day	33% 17% 28% 16% 5% 1	490
	21st to end	Day	40% 18% 24% 15% 3	539
November	1st to 10th	Day	33% 19% 28% 14% 6% 1	359
	11th to 20th	Day	43% 20% 25% 9% 3 1	200
	21st to end	Day	43% 27% 23% 7% 1	200
December	1st to 10th	Day	42% 24% 22% 8% 3	196
	11th to 20th	Day	42% 24% 23% 11%	180
	21st to end	Day	40% 25% 27% 6% 1	198
January	1st to 10th	Night	35% 25% 26% 10% 3	760
	11th to 20th	Night	35% 27% 26% 11% 2	760
	21st to end	Night	27% 24% 32% 14% 3	836
February	1st to 10th	Night	33% 25% 27% 14% 1	760
	11th to 20th	Night	30% 24% 33% 11% 2	743
	21st to end	Night	34% 23% 28% 14% 1	628
March	1st to 10th	Night	29% 19% 32% 16% 4	760
	11th to 20th	Night	32% 21% 28% 16% 4	760
	21st to end	Night	27% 17% 33% 16% 6% 1	836
April	1st to 10th	Night	30% 17% 30% 20% 3	760
	11th to 20th	Night	29% 15% 28% 21% 6% 1	751
	21st to end	Night	26% 10% 31% 26% 6% 1	584
May	1st to 10th	Night	27% 10% 22% 30% 10% 1	570
	11th to 20th	Night	15% 8% 33% 37% 7%	392
	21st to end	Night	17% 9% 26% 33% 14% 1	411
June	1st to 10th	Night	16% 8% 32% 32% 11% 1	380
	11th to 20th	Night	16% 10% 27% 38% 9%	380
	21st to end	Night	18% 7% 33% 32% 9%	380
July	1st to 10th	Night	12% 5% 23% 41% 17% 2	370
	11th to 20th	Night	13% 5% 27% 36% 17% 1	368
	21st to end	Night	14% 4 28% 35% 18% 1	605
August	1st to 10th	Night	13% 5% 20% 41% 20% 2	567
	11th to 20th	Night	13% 6% 22% 33% 24% 2	564
	21st to end	Night	14% 7% 25% 32% 21% 2	758
September	1st to 10th	Night	20% 9% 23% 29% 17% 3	760
	11th to 20th	Night	15% 7% 22% 28% 26% 3	760
	21st to end	Night	23% 12% 23% 26% 14% 3	760
October	1st to 10th	Night	23% 12% 28% 22% 15% 1	760
	11th to 20th	Night	31% 18% 24% 20% 6% 1	760
	21st to end	Night	38% 16% 27% 17% 3	836
November	1st to 10th	Night	29% 16% 29% 19% 7% 1	780
	11th to 20th	Night	33% 20% 28% 13% 6% 1	800
	21st to end	Night	35% 23% 27% 12% 4	800
December	1st to 10th	Night	41% 25% 19% 11% 4	795
	11th to 20th	Night	37% 25% 25% 11% 2	760
	21st to end	Night	37% 25% 26% 10% 1	836

Page generated at 2024-12-06 03:54:53. Version ac07

Copyright © 2024 Attilla Danko.