Batavia
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Batavia clear sky chart from 2005-11-06 to 2024-11-02.

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 7% 5% 4 4 4 5% 7% 37%	101720
	Night	15% 10% 3 7% 4 4 4 3 5% 7% 38%	97219
Transparency	Day	45% 7% 11% 22% 14% 2	101526
	Night	45% 6% 11% 22% 14% 2	97084
Seeing	Day	20% 12% 27% 22% 13% 6%	15240
	Night	19% 10% 26% 28% 15% 2	24750

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	16% 16% 7% 11% 5% 4 4 3 4 5% 25%	2836
	11th to 20th	Day	16% 14% 6% 14% 5% 7% 5% 3 4 5% 22%	2840
	21st to end	Day	27% 16% 9% 8% 4 4 3 2 4 5% 19%	3124
February	1st to 10th	Day	19% 13% 5% 8% 5% 3 4 3 4 5% 30%	1796
	11th to 20th	Day	17% 11% 5% 11% 6% 4 4 3 4 5% 31%	1848
	21st to end	Day	19% 14% 6% 8% 4 4 3 3 4 6% 30%	1570
March	1st to 10th	Day	22% 16% 5% 8% 4 3 3 3 4 5% 26%	3173
	11th to 20th	Day	15% 7% 3 7% 4 4 4 3 5% 7% 40%	3480
	21st to end	Day	17% 10% 3 7% 4 4 4 3 5% 7% 36%	3815
April	1st to 10th	Day	15% 10% 3 7% 5% 4 5% 3 5% 7% 36%	2218
	11th to 20th	Day	17% 8% 3 7% 4 3 4 3 5% 7% 39%	2318
	21st to end	Day	17% 8% 3 8% 5% 4 4 3 5% 7% 35%	2470
May	1st to 10th	Day	21% 10% 3 7% 5% 4 5% 4 5% 7% 29%	4082
	11th to 20th	Day	20% 8% 3 6% 4 3 5% 3 5% 7% 35%	4081
	21st to end	Day	9% 7% 3 7% 6% 5% 6% 5% 8% 9% 34%	4476
June	1st to 10th	Day	11% 6% 2 6% 5% 5% 5% 5% 6% 8% 40%	2470
	11th to 20th	Day	9% 5% 2 6% 5% 4 5% 4 8% 10% 43%	2589
	21st to end	Day	9% 6% 2 7% 6% 5% 5% 5% 6% 9% 40%	2660
July	1st to 10th	Day	12% 7% 2 8% 5% 4 5% 5% 6% 9% 38%	4440
	11th to 20th	Day	7% 4 2 6% 4 5% 5% 4 7% 11% 46%	4184
	21st to end	Day	11% 7% 3 9% 6% 6% 6% 5% 8% 8% 31%	4466
August	1st to 10th	Day	9% 5% 2 7% 3 5% 4 5% 7% 11% 43%	4104
	11th to 20th	Day	7% 6% 3 6% 5% 5% 5% 5% 8% 10% 41%	4044
	21st to end	Day	5% 4 2 5% 4 4 4 4 6% 8% 55%	4244
September	1st to 10th	Day	13% 6% 2 5% 4 4 4 4 5% 6% 49%	2147
	11th to 20th	Day	9% 4 2 5% 4 4 5% 4 6% 9% 48%	2090
	21st to end	Day	16% 6% 2 6% 5% 4 3 3 4 6% 46%	2090
October	1st to 10th	Day	11% 5% 1 5% 4 4 5% 4 4 6% 50%	2090
	11th to 20th	Day	14% 6% 2 6% 4 3 4 3 5% 7% 46%	1918
	21st to end	Day	19% 9% 2 6% 3 4 3 3 5% 6% 40%	1969
November	1st to 10th	Day	10% 7% 2 5% 4 3 3 3 4 6% 53%	1681
	11th to 20th	Day	13% 12% 3 8% 5% 4 4 3 4 6% 38%	1710
	21st to end	Day	17% 11% 3 8% 4 4 4 3 4 5% 38%	1710
December	1st to 10th	Day	21% 13% 6% 9% 5% 4 4 4 4 4 26%	1710
	11th to 20th	Day	16% 15% 5% 10% 6% 4 4 3 4 5% 29%	2153
	21st to end	Day	20% 21% 5% 10% 5% 4 4 3 4 6% 18%	3124
January	1st to 10th	Night	16% 18% 6% 11% 5% 5% 5% 4 4 5% 22%	4109
	11th to 20th	Night	15% 17% 6% 14% 6% 5% 3 3 4 4 23%	4120
	21st to end	Night	27% 17% 5% 8% 4 4 3 3 4 5% 21%	4532
February	1st to 10th	Night	21% 12% 5% 8% 4 4 4 3 4 5% 29%	2380
	11th to 20th	Night	18% 11% 4 8% 5% 4 5% 3 4 6% 31%	2218
	21st to end	Night	20% 16% 4 8% 4 4 3 2 4 6% 30%	1884
March	1st to 10th	Night	21% 14% 3 6% 4 4 3 3 4 5% 32%	3680
	11th to 20th	Night	14% 8% 3 6% 3 4 4 4 5% 7% 44%	3480
	21st to end	Night	16% 10% 3 6% 5% 4 4 3 4 6% 39%	3817
April	1st to 10th	Night	13% 10% 3 6% 6% 4 4 4 6% 8% 36%	1977
	11th to 20th	Night	15% 8% 2 5% 5% 3 4 4 6% 7% 41%	1811
	21st to end	Night	16% 8% 3 7% 5% 4 3 3 5% 8% 37%	1710
May	1st to 10th	Night	22% 12% 3 8% 6% 4 4 3 6% 6% 27%	2813
	11th to 20th	Night	19% 7% 2 5% 4 4 4 4 6% 8% 38%	2812
	21st to end	Night	9% 5% 2 6% 4 4 4 4 7% 9% 45%	3079
June	1st to 10th	Night	9% 5% 2 5% 4 4 4 3 6% 9% 48%	1710
	11th to 20th	Night	8% 4 2 5% 4 4 4 3 7% 11% 48%	1584
	21st to end	Night	6% 4 2 4 5% 5% 5% 5% 8% 10% 46%	1520
July	1st to 10th	Night	10% 5% 2 6% 4 4 4 3 5% 8% 49%	2530
	11th to 20th	Night	5% 5% 2 5% 4 5% 4 4 6% 9% 50%	2773
	21st to end	Night	11% 7% 3 8% 6% 5% 4 4 6% 9% 37%	3087
August	1st to 10th	Night	8% 5% 3 7% 5% 4 5% 4 7% 8% 46%	2825
	11th to 20th	Night	8% 7% 3 7% 5% 4 5% 3 6% 8% 44%	2785
	21st to end	Night	4 3 1 4 3 4 4 3 6% 10% 60%	3408
September	1st to 10th	Night	11% 5% 2 4 3 4 3 4 5% 7% 51%	2013
	11th to 20th	Night	8% 4 2 6% 3 4 5% 4 5% 7% 53%	2090
	21st to end	Night	14% 5% 3 6% 4 3 4 3 5% 6% 48%	2090
October	1st to 10th	Night	8% 5% 2 5% 4 3 4 3 5% 7% 55%	2090
	11th to 20th	Night	14% 6% 2 5% 4 4 4 4 5% 7% 45%	2261
	21st to end	Night	18% 8% 2 5% 4 4 4 3 4 5% 42%	2627
November	1st to 10th	Night	13% 7% 2 5% 4 3 4 3 4 7% 47%	2420
	11th to 20th	Night	15% 9% 3 8% 4 4 4 3 5% 6% 40%	2470
	21st to end	Night	17% 13% 3 7% 5% 4 4 3 4 6% 34%	2470
December	1st to 10th	Night	20% 14% 4 8% 5% 4 3 3 5% 5% 28%	2470
	11th to 20th	Night	18% 13% 6% 8% 5% 4 3 3 4 6% 29%	3042
	21st to end	Night	20% 19% 6% 11% 6% 5% 4 3 5% 5% 17%	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	60% 5% 12% 13% 9%	2837
	11th to 20th	Day	64% 5% 11% 14% 6%	2840
	21st to end	Day	69% 4 9% 15% 3	3124
February	1st to 10th	Day	57% 4 10% 18% 10% 2	1796
	11th to 20th	Day	56% 4 10% 18% 11% 1	1858
	21st to end	Day	57% 4 9% 19% 10% 2	1570
March	1st to 10th	Day	57% 8% 8% 19% 8% 1	3173
	11th to 20th	Day	41% 6% 10% 25% 15% 1	3480
	21st to end	Day	47% 7% 11% 24% 11% 1	3815
April	1st to 10th	Day	46% 6% 10% 23% 12% 2	2218
	11th to 20th	Day	44% 6% 10% 22% 14% 3	2318
	21st to end	Day	48% 7% 12% 20% 11% 2	2470
May	1st to 10th	Day	51% 8% 12% 20% 8% 1	4120
	11th to 20th	Day	47% 7% 12% 21% 12% 1	4085
	21st to end	Day	39% 11% 14% 19% 15% 2	4489
June	1st to 10th	Day	39% 9% 11% 23% 16% 2	2470
	11th to 20th	Day	34% 9% 14% 24% 17% 1	2589
	21st to end	Day	39% 9% 13% 22% 14% 4	2660
July	1st to 10th	Day	41% 7% 11% 21% 18% 1	4371
	11th to 20th	Day	31% 7% 11% 32% 18% 1	4113
	21st to end	Day	47% 9% 12% 18% 12% 2	4324
August	1st to 10th	Day	33% 8% 14% 34% 11% 1	4091
	11th to 20th	Day	35% 7% 11% 31% 15%	4083
	21st to end	Day	26% 7% 15% 28% 21% 3	4243
September	1st to 10th	Day	35% 6% 12% 22% 20% 5%	2147
	11th to 20th	Day	32% 7% 12% 24% 23% 3	2090
	21st to end	Day	40% 5% 9% 23% 21% 2	2090
October	1st to 10th	Day	33% 7% 10% 24% 24% 2	2090
	11th to 20th	Day	38% 4 9% 26% 20% 3	1918
	21st to end	Day	45% 5% 11% 22% 16% 2	1969
November	1st to 10th	Day	34% 4 10% 28% 21% 3	1681
	11th to 20th	Day	47% 5% 7% 21% 17% 3	1710
	21st to end	Day	48% 5% 10% 22% 14% 1	1710
December	1st to 10th	Day	61% 5% 10% 17% 6%	1710
	11th to 20th	Day	56% 6% 9% 18% 11%	2150
	21st to end	Day	68% 6% 8% 11% 6% 1	3124
January	1st to 10th	Night	62% 8% 9% 14% 8%	4109
	11th to 20th	Night	64% 5% 9% 14% 7%	4120
	21st to end	Night	65% 5% 8% 16% 6% 1	4532
February	1st to 10th	Night	57% 4 11% 19% 7% 1	2380
	11th to 20th	Night	54% 5% 10% 19% 12% 1	2219
	21st to end	Night	57% 4 10% 16% 9% 3	1884
March	1st to 10th	Night	53% 5% 7% 23% 10% 1	3680
	11th to 20th	Night	38% 8% 12% 26% 15% 1	3480
	21st to end	Night	45% 6% 9% 27% 12% 1	3817
April	1st to 10th	Night	44% 7% 10% 23% 13% 2	1977
	11th to 20th	Night	40% 7% 10% 19% 18% 6%	1811
	21st to end	Night	45% 5% 12% 21% 13% 3	1710
May	1st to 10th	Night	55% 8% 9% 18% 8% 2	2840
	11th to 20th	Night	42% 9% 14% 25% 9% 1	2813
	21st to end	Night	31% 8% 16% 26% 15% 4	3087
June	1st to 10th	Night	31% 7% 13% 26% 20% 3	1710
	11th to 20th	Night	30% 7% 16% 22% 21% 4	1584
	21st to end	Night	29% 11% 17% 22% 17% 5%	1520
July	1st to 10th	Night	33% 8% 11% 24% 19% 5%	2490
	11th to 20th	Night	29% 6% 13% 30% 20% 2	2722
	21st to end	Night	42% 6% 13% 22% 13% 4	2988
August	1st to 10th	Night	34% 7% 14% 32% 12% 1	2814
	11th to 20th	Night	36% 8% 10% 27% 18% 1	2812
	21st to end	Night	20% 6% 16% 32% 23% 3	3408
September	1st to 10th	Night	31% 7% 12% 25% 20% 6%	2013
	11th to 20th	Night	30% 6% 11% 23% 27% 3	2090
	21st to end	Night	37% 6% 9% 21% 25% 2	2090
October	1st to 10th	Night	29% 6% 11% 27% 24% 3	2090
	11th to 20th	Night	37% 6% 9% 25% 21% 2	2261
	21st to end	Night	44% 4 9% 21% 18% 3	2627
November	1st to 10th	Night	37% 5% 10% 21% 23% 4	2420
	11th to 20th	Night	45% 4 9% 20% 19% 3	2470
	21st to end	Night	52% 4 10% 20% 12% 2	2470
December	1st to 10th	Night	57% 6% 10% 18% 9% 1	2470
	11th to 20th	Night	55% 5% 10% 20% 9% 1	3044
	21st to end	Night	68% 6% 9% 13% 5%	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	28% 24% 32% 14% 3	270
	11th to 20th	Day	33% 25% 34% 7% 1	270
	21st to end	Day	34% 23% 30% 12% 1	297
February	1st to 10th	Day	29% 26% 31% 12% 2	270
	11th to 20th	Day	33% 30% 30% 6% 1	270
	21st to end	Day	37% 20% 37% 6%	225
March	1st to 10th	Day	27% 32% 28% 13% 1	297
	11th to 20th	Day	25% 23% 32% 15% 5%	460
	21st to end	Day	33% 18% 29% 15% 5%	506
April	1st to 10th	Day	25% 18% 30% 18% 8% 1	460
	11th to 20th	Day	26% 19% 27% 15% 9% 3	452
	21st to end	Day	25% 19% 32% 13% 9% 2	460
May	1st to 10th	Day	27% 16% 30% 16% 7% 4	463
	11th to 20th	Day	24% 9% 29% 22% 10% 5%	487
	21st to end	Day	15% 7% 26% 29% 15% 8%	529
June	1st to 10th	Day	16% 7% 24% 29% 16% 8%	490
	11th to 20th	Day	12% 6% 24% 33% 17% 7%	609
	21st to end	Day	10% 7% 29% 30% 18% 6%	680
July	1st to 10th	Day	15% 4 18% 26% 20% 17%	671
	11th to 20th	Day	10% 4 23% 30% 23% 10%	520
	21st to end	Day	12% 3 21% 31% 22% 11%	532
August	1st to 10th	Day	12% 4 14% 32% 24% 14%	486
	11th to 20th	Day	11% 5% 21% 32% 21% 9%	479
	21st to end	Day	9% 4 16% 32% 26% 13%	539
September	1st to 10th	Day	14% 3 19% 29% 26% 9%	490
	11th to 20th	Day	11% 3 18% 27% 30% 12%	490
	21st to end	Day	21% 9% 21% 23% 20% 7%	490
October	1st to 10th	Day	12% 6% 27% 31% 19% 6%	490
	11th to 20th	Day	17% 13% 32% 22% 12% 3	490
	21st to end	Day	23% 11% 40% 19% 6%	418
November	1st to 10th	Day	16% 17% 34% 21% 9% 3	273
	11th to 20th	Day	21% 24% 29% 18% 5% 2	270
	21st to end	Day	27% 19% 36% 16% 3	270
December	1st to 10th	Day	26% 20% 33% 15% 5%	270
	11th to 20th	Day	20% 25% 39% 11% 5%	270
	21st to end	Day	32% 19% 37% 10% 2 1	297
January	1st to 10th	Night	23% 22% 32% 19% 4	760
	11th to 20th	Night	29% 20% 32% 16% 3	760
	21st to end	Night	26% 18% 34% 20% 3	836
February	1st to 10th	Night	29% 13% 34% 21% 2	760
	11th to 20th	Night	25% 21% 31% 21% 1	743
	21st to end	Night	29% 17% 36% 17% 1	628
March	1st to 10th	Night	24% 20% 30% 21% 5%	760
	11th to 20th	Night	25% 16% 32% 20% 6% 1	760
	21st to end	Night	24% 13% 33% 24% 7%	836
April	1st to 10th	Night	20% 13% 35% 25% 7%	647
	11th to 20th	Night	20% 11% 33% 24% 11% 1	563
	21st to end	Night	18% 11% 38% 24% 8% 1	570
May	1st to 10th	Night	22% 9% 30% 26% 11% 1	570
	11th to 20th	Night	18% 6% 24% 32% 18% 2	561
	21st to end	Night	10% 3 23% 35% 23% 6%	617
June	1st to 10th	Night	11% 3 22% 39% 24% 2	570
	11th to 20th	Night	10% 3 16% 44% 25% 3	570
	21st to end	Night	7% 3 25% 38% 24% 3	570
July	1st to 10th	Night	15% 1 11% 32% 33% 9%	555
	11th to 20th	Night	8% 1 16% 34% 37% 3	552
	21st to end	Night	13% 2 11% 39% 31% 4	624
August	1st to 10th	Night	9% 2 10% 40% 36% 4	567
	11th to 20th	Night	10% 2 12% 41% 31% 5%	564
	21st to end	Night	7% 1 14% 34% 38% 7%	627
September	1st to 10th	Night	14% 3 13% 33% 31% 5%	683
	11th to 20th	Night	10% 3 15% 33% 33% 6%	760
	21st to end	Night	16% 6% 21% 32% 22% 3	760
October	1st to 10th	Night	11% 5% 23% 34% 23% 3	760
	11th to 20th	Night	18% 9% 28% 30% 14% 1	760
	21st to end	Night	23% 9% 34% 23% 11%	836
November	1st to 10th	Night	17% 11% 28% 27% 16% 2	745
	11th to 20th	Night	20% 17% 29% 24% 9% 1	760
	21st to end	Night	25% 13% 27% 28% 7% 1	760
December	1st to 10th	Night	28% 14% 31% 22% 5%	760
	11th to 20th	Night	26% 14% 32% 23% 5% 1	760
	21st to end	Night	30% 15% 31% 21% 3	836

Page generated at 2024-10-30 01:22:57. Version ac07

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