Milton
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Milton 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% 9% 3 8% 5% 5% 5% 4 6% 7% 34%	101674
	Night	15% 9% 3 7% 5% 5% 5% 4 5% 7% 36%	97294
Transparency	Day	46% 7% 14% 21% 11% 1	105280
	Night	46% 7% 14% 21% 12% 1	101776
Seeing	Day	17% 12% 28% 26% 13% 5%	14674
	Night	17% 11% 30% 28% 12% 1	23867

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	14% 17% 5% 9% 5% 5% 4 3 4 6% 26%	2517
	11th to 20th	Day	11% 17% 8% 15% 8% 5% 5% 4 4 5% 18%	2817
	21st to end	Day	22% 18% 6% 12% 6% 5% 4 3 4 4 17%	3124
February	1st to 10th	Day	13% 16% 4 11% 8% 6% 6% 4 5% 6% 21%	1710
	11th to 20th	Day	11% 14% 5% 11% 7% 5% 5% 3 5% 7% 25%	1663
	21st to end	Day	18% 11% 4 10% 6% 4 5% 5% 4 5% 26%	1481
March	1st to 10th	Day	18% 11% 4 10% 6% 6% 4 3 4 5% 29%	3432
	11th to 20th	Day	11% 12% 5% 9% 6% 6% 5% 4 6% 6% 31%	3480
	21st to end	Day	15% 10% 3 7% 5% 5% 5% 4 6% 6% 34%	3815
April	1st to 10th	Day	15% 12% 4 8% 6% 6% 5% 4 5% 6% 30%	2223
	11th to 20th	Day	18% 9% 3 6% 4 5% 4 3 5% 6% 36%	2347
	21st to end	Day	19% 10% 3 7% 5% 4 5% 3 5% 5% 34%	2470
May	1st to 10th	Day	18% 7% 3 7% 4 5% 4 4 6% 7% 35%	4108
	11th to 20th	Day	17% 9% 3 8% 5% 5% 5% 4 6% 7% 31%	4302
	21st to end	Day	11% 5% 2 6% 4 4 4 4 6% 8% 47%	4837
June	1st to 10th	Day	14% 6% 2 7% 5% 4 5% 5% 7% 7% 39%	2660
	11th to 20th	Day	11% 6% 2 7% 5% 4 6% 4 7% 8% 40%	2660
	21st to end	Day	13% 5% 3 6% 4 5% 5% 5% 6% 9% 40%	2837
July	1st to 10th	Day	9% 4 2 5% 5% 5% 5% 5% 8% 10% 41%	4536
	11th to 20th	Day	9% 4 2 5% 5% 4 5% 5% 8% 9% 45%	4392
	21st to end	Day	8% 5% 2 6% 5% 5% 5% 5% 7% 10% 43%	4466
August	1st to 10th	Day	17% 6% 2 6% 3 4 4 5% 6% 8% 38%	4104
	11th to 20th	Day	9% 6% 3 8% 5% 6% 5% 4 7% 10% 36%	4044
	21st to end	Day	10% 5% 2 6% 4 5% 5% 4 6% 9% 43%	4382
September	1st to 10th	Day	13% 5% 2 5% 5% 5% 5% 5% 5% 8% 42%	2280
	11th to 20th	Day	11% 5% 2 6% 4 4 5% 4 5% 8% 46%	2138
	21st to end	Day	15% 5% 2 6% 5% 6% 6% 5% 7% 7% 35%	2069
October	1st to 10th	Day	19% 8% 2 7% 4 5% 5% 3 5% 8% 36%	1900
	11th to 20th	Day	19% 7% 3 9% 5% 5% 5% 3 6% 6% 31%	1900
	21st to end	Day	21% 12% 3 7% 6% 7% 5% 4 5% 6% 24%	2090
November	1st to 10th	Day	12% 10% 2 8% 5% 6% 5% 5% 7% 6% 33%	1652
	11th to 20th	Day	13% 12% 3 9% 7% 5% 6% 4 6% 8% 26%	1520
	21st to end	Day	16% 14% 5% 8% 6% 6% 5% 4 6% 7% 24%	1520
December	1st to 10th	Day	14% 17% 5% 11% 8% 6% 6% 5% 7% 5% 18%	1520
	11th to 20th	Day	17% 14% 5% 10% 6% 7% 5% 4 7% 5% 21%	1906
	21st to end	Day	28% 17% 7% 11% 5% 5% 4 3 3 4 11%	2772
January	1st to 10th	Night	16% 15% 5% 10% 6% 5% 5% 4 5% 6% 23%	4429
	11th to 20th	Night	13% 13% 6% 11% 8% 6% 6% 4 6% 7% 21%	4138
	21st to end	Night	21% 11% 6% 10% 6% 5% 5% 4 5% 5% 22%	4532
February	1st to 10th	Night	14% 12% 4 11% 7% 5% 6% 4 6% 7% 25%	2470
	11th to 20th	Night	11% 12% 5% 10% 6% 7% 5% 4 5% 6% 29%	2403
	21st to end	Night	13% 11% 3 10% 6% 5% 5% 4 6% 7% 29%	1971
March	1st to 10th	Night	20% 8% 3 8% 5% 5% 5% 4 6% 6% 32%	3408
	11th to 20th	Night	11% 9% 4 7% 4 4 4 4 6% 7% 41%	3479
	21st to end	Night	16% 8% 2 7% 4 4 4 3 4 5% 43%	3817
April	1st to 10th	Night	17% 10% 4 6% 5% 5% 5% 4 5% 6% 33%	1955
	11th to 20th	Night	16% 7% 3 7% 6% 4 4 3 5% 7% 38%	1797
	21st to end	Night	16% 9% 2 6% 5% 4 3 4 5% 7% 38%	1710
May	1st to 10th	Night	18% 7% 3 7% 4 3 5% 3 4 6% 40%	2833
	11th to 20th	Night	17% 8% 3 7% 5% 4 5% 3 5% 8% 36%	2576
	21st to end	Night	9% 4 1 5% 4 4 4 4 5% 8% 52%	2738
June	1st to 10th	Night	11% 4 2 6% 5% 4 5% 4 6% 9% 43%	1520
	11th to 20th	Night	11% 4 3 6% 4 5% 4 5% 7% 8% 44%	1520
	21st to end	Night	11% 5% 2 6% 5% 4 4 4 6% 7% 47%	1331
July	1st to 10th	Night	6% 4 1 5% 4 4 4 4 5% 9% 53%	2413
	11th to 20th	Night	11% 4 1 5% 4 3 4 3 6% 8% 52%	2551
	21st to end	Night	6% 4 2 5% 4 5% 4 4 6% 9% 52%	3087
August	1st to 10th	Night	11% 5% 2 6% 4 4 5% 3 5% 7% 47%	2825
	11th to 20th	Night	11% 5% 2 5% 4 4 4 4 5% 7% 50%	2785
	21st to end	Night	10% 5% 2 6% 3 4 5% 4 6% 6% 48%	3242
September	1st to 10th	Night	10% 5% 2 6% 4 5% 4 4 6% 7% 48%	1900
	11th to 20th	Night	11% 3 2 5% 3 3 4 3 5% 8% 55%	2039
	21st to end	Night	15% 7% 3 6% 5% 4 5% 3 6% 6% 41%	2110
October	1st to 10th	Night	17% 7% 2 7% 4 3 4 3 5% 6% 42%	2280
	11th to 20th	Night	17% 8% 3 6% 5% 6% 4 4 5% 6% 37%	2280
	21st to end	Night	20% 9% 3 7% 5% 4 5% 3 5% 7% 31%	2508
November	1st to 10th	Night	15% 7% 2 6% 5% 5% 4 4 6% 6% 39%	2495
	11th to 20th	Night	14% 11% 4 7% 5% 5% 6% 5% 7% 7% 30%	2660
	21st to end	Night	17% 10% 3 7% 5% 5% 5% 4 7% 8% 28%	2660
December	1st to 10th	Night	17% 14% 5% 8% 5% 5% 5% 3 7% 7% 24%	2660
	11th to 20th	Night	15% 15% 5% 10% 5% 5% 5% 4 6% 7% 22%	3288
	21st to end	Night	27% 18% 6% 10% 5% 4 4 3 4 5% 13%	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	57% 9% 16% 11% 8%	2518
	11th to 20th	Day	68% 5% 13% 10% 4	2817
	21st to end	Day	71% 5% 10% 8% 4	3124
February	1st to 10th	Day	63% 7% 13% 13% 3 1	1710
	11th to 20th	Day	58% 7% 11% 14% 8% 2	1672
	21st to end	Day	58% 7% 13% 14% 7% 1	1481
March	1st to 10th	Day	57% 7% 12% 17% 6% 1	3435
	11th to 20th	Day	51% 6% 14% 19% 8% 1	3480
	21st to end	Day	47% 6% 14% 21% 11% 2	3815
April	1st to 10th	Day	53% 5% 13% 17% 11% 1	2223
	11th to 20th	Day	48% 5% 12% 21% 13% 1	2347
	21st to end	Day	51% 6% 11% 17% 13% 2	2470
May	1st to 10th	Day	45% 7% 15% 19% 11% 3	4120
	11th to 20th	Day	48% 11% 13% 19% 8% 1	4306
	21st to end	Day	34% 7% 14% 22% 19% 4	4837
June	1st to 10th	Day	41% 8% 13% 22% 15% 2	2660
	11th to 20th	Day	38% 7% 14% 23% 15% 1	2660
	21st to end	Day	39% 7% 14% 24% 15% 1	2837
July	1st to 10th	Day	33% 7% 16% 26% 15% 2	4466
	11th to 20th	Day	31% 7% 15% 34% 11% 1	4317
	21st to end	Day	34% 10% 16% 22% 18% 1	4324
August	1st to 10th	Day	42% 7% 15% 22% 14% 1	4091
	11th to 20th	Day	40% 7% 18% 25% 10%	4083
	21st to end	Day	35% 7% 14% 33% 11% 1	4382
September	1st to 10th	Day	39% 8% 15% 27% 11% 1	2280
	11th to 20th	Day	34% 7% 14% 30% 15%	2138
	21st to end	Day	44% 8% 15% 24% 8% 1	2069
October	1st to 10th	Day	37% 7% 16% 26% 13% 1	3160
	11th to 20th	Day	40% 6% 15% 23% 16%	3140
	21st to end	Day	51% 7% 15% 20% 7%	3428
November	1st to 10th	Day	46% 9% 15% 22% 8% 1	1652
	11th to 20th	Day	53% 8% 17% 15% 7%	1520
	21st to end	Day	57% 8% 16% 14% 4	1520
December	1st to 10th	Day	63% 8% 14% 10% 4	1520
	11th to 20th	Day	61% 9% 14% 10% 6%	1906
	21st to end	Day	76% 7% 8% 8% 1	2772
January	1st to 10th	Night	59% 9% 14% 13% 4	4429
	11th to 20th	Night	61% 9% 17% 9% 3	4138
	21st to end	Night	64% 6% 12% 13% 4 1	4532
February	1st to 10th	Night	58% 7% 13% 18% 4 1	2470
	11th to 20th	Night	56% 6% 13% 16% 9% 1	2405
	21st to end	Night	53% 6% 16% 17% 8%	1971
March	1st to 10th	Night	50% 7% 15% 21% 6% 1	3418
	11th to 20th	Night	42% 6% 18% 20% 12% 2	3480
	21st to end	Night	43% 5% 10% 23% 17% 2	3817
April	1st to 10th	Night	51% 6% 11% 19% 13% 1	1955
	11th to 20th	Night	47% 5% 10% 20% 16% 2	1797
	21st to end	Night	45% 7% 10% 20% 15% 3	1710
May	1st to 10th	Night	44% 8% 12% 17% 15% 3	2840
	11th to 20th	Night	45% 12% 14% 18% 9% 2	2577
	21st to end	Night	29% 7% 14% 23% 24% 3	2739
June	1st to 10th	Night	37% 7% 12% 24% 18% 1	1520
	11th to 20th	Night	34% 7% 14% 25% 18% 2	1520
	21st to end	Night	35% 7% 14% 26% 17% 1	1331
July	1st to 10th	Night	29% 5% 14% 25% 22% 4	2373
	11th to 20th	Night	30% 6% 13% 32% 18% 1	2503
	21st to end	Night	29% 9% 16% 27% 18% 2	2988
August	1st to 10th	Night	36% 7% 12% 27% 15% 3	2814
	11th to 20th	Night	33% 6% 16% 31% 12% 1	2812
	21st to end	Night	33% 7% 14% 30% 15% 1	3242
September	1st to 10th	Night	34% 8% 14% 28% 15% 2	1900
	11th to 20th	Night	28% 7% 12% 33% 19%	2039
	21st to end	Night	42% 7% 12% 27% 11%	2110
October	1st to 10th	Night	32% 5% 11% 26% 25% 1	3800
	11th to 20th	Night	42% 6% 12% 25% 15%	3779
	21st to end	Night	40% 6% 16% 26% 12% 1	4120
November	1st to 10th	Night	42% 8% 14% 23% 13% 1	2495
	11th to 20th	Night	49% 8% 16% 19% 8% 1	2660
	21st to end	Night	53% 7% 20% 15% 4	2660
December	1st to 10th	Night	58% 9% 15% 14% 4	2660
	11th to 20th	Night	59% 9% 15% 14% 3	3288
	21st to end	Night	74% 8% 9% 7% 2	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	17% 18% 36% 19% 8% 2	180
	11th to 20th	Day	21% 20% 41% 12% 5% 1	265
	21st to end	Day	23% 19% 33% 22% 3	297
February	1st to 10th	Day	21% 19% 44% 13% 4	270
	11th to 20th	Day	19% 23% 38% 18% 1	270
	21st to end	Day	27% 24% 34% 15%	227
March	1st to 10th	Day	21% 12% 36% 24% 6%	460
	11th to 20th	Day	19% 18% 35% 20% 7% 1	460
	21st to end	Day	24% 13% 33% 21% 8% 1	506
April	1st to 10th	Day	18% 17% 32% 26% 7% 1	460
	11th to 20th	Day	23% 18% 27% 21% 8% 3	452
	21st to end	Day	23% 12% 34% 21% 8% 2	460
May	1st to 10th	Day	18% 12% 30% 25% 11% 5%	463
	11th to 20th	Day	17% 7% 27% 30% 15% 5%	487
	21st to end	Day	12% 6% 28% 29% 18% 7%	529
June	1st to 10th	Day	12% 10% 31% 31% 13% 3	490
	11th to 20th	Day	12% 8% 24% 33% 19% 4	490
	21st to end	Day	14% 8% 30% 31% 14% 4	667
July	1st to 10th	Day	8% 4 22% 36% 21% 9%	542
	11th to 20th	Day	13% 5% 22% 29% 21% 10%	484
	21st to end	Day	8% 4 22% 39% 19% 7%	532
August	1st to 10th	Day	10% 5% 22% 31% 22% 11%	486
	11th to 20th	Day	8% 6% 20% 32% 22% 13%	479
	21st to end	Day	10% 7% 22% 30% 23% 8%	539
September	1st to 10th	Day	12% 6% 21% 30% 20% 11%	490
	11th to 20th	Day	10% 3 18% 28% 26% 15%	490
	21st to end	Day	15% 10% 27% 24% 17% 7%	490
October	1st to 10th	Day	20% 13% 22% 24% 14% 6%	490
	11th to 20th	Day	20% 14% 31% 23% 10% 2	490
	21st to end	Day	27% 14% 30% 21% 8% 1	539
November	1st to 10th	Day	15% 24% 29% 22% 9% 1	272
	11th to 20th	Day	22% 21% 29% 19% 6% 2	180
	21st to end	Day	22% 17% 38% 19% 4	180
December	1st to 10th	Day	21% 23% 33% 19% 4	180
	11th to 20th	Day	22% 27% 30% 19% 2	180
	21st to end	Day	25% 19% 40% 13% 3	198
January	1st to 10th	Night	20% 18% 37% 19% 6%	760
	11th to 20th	Night	24% 18% 34% 20% 4	760
	21st to end	Night	17% 14% 40% 24% 6%	836
February	1st to 10th	Night	19% 17% 41% 20% 3	760
	11th to 20th	Night	19% 16% 38% 23% 3	743
	21st to end	Night	18% 19% 36% 23% 4	628
March	1st to 10th	Night	18% 13% 37% 27% 6%	760
	11th to 20th	Night	19% 15% 37% 22% 6%	760
	21st to end	Night	20% 12% 31% 28% 8% 1	836
April	1st to 10th	Night	21% 11% 35% 28% 5%	760
	11th to 20th	Night	18% 12% 34% 26% 9% 1	673
	21st to end	Night	20% 7% 29% 33% 10%	570
May	1st to 10th	Night	15% 7% 28% 32% 15% 2	570
	11th to 20th	Night	16% 4 27% 38% 14% 1	429
	21st to end	Night	11% 3 24% 35% 25% 1	411
June	1st to 10th	Night	13% 3 28% 39% 15% 1	380
	11th to 20th	Night	12% 3 30% 38% 17% 1	380
	21st to end	Night	10% 7% 22% 43% 18%	380
July	1st to 10th	Night	6% 2 22% 44% 25% 1	370
	11th to 20th	Night	9% 2 23% 40% 23% 2	386
	21st to end	Night	8% 2 19% 45% 24% 2	624
August	1st to 10th	Night	9% 3 16% 42% 27% 3	567
	11th to 20th	Night	7% 3 16% 38% 32% 3	564
	21st to end	Night	10% 3 21% 35% 27% 3	693
September	1st to 10th	Night	11% 6% 21% 33% 24% 5%	760
	11th to 20th	Night	11% 5% 19% 32% 29% 6%	760
	21st to end	Night	16% 8% 21% 30% 21% 4	760
October	1st to 10th	Night	18% 8% 26% 26% 19% 3	760
	11th to 20th	Night	18% 13% 30% 28% 9% 1	760
	21st to end	Night	24% 13% 30% 28% 5%	836
November	1st to 10th	Night	19% 12% 28% 29% 10% 1	755
	11th to 20th	Night	18% 15% 35% 23% 7% 2	760
	21st to end	Night	22% 15% 35% 23% 5%	760
December	1st to 10th	Night	25% 18% 34% 18% 5% 1	760
	11th to 20th	Night	22% 18% 38% 18% 5%	760
	21st to end	Night	27% 16% 35% 19% 3	836

Page generated at 2024-11-01 22:47:35. Version ac07

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