Peotone
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Peotone 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	13% 9% 3 8% 5% 4 4 4 6% 7% 37%	101213
	Night	14% 10% 4 8% 5% 4 4 3 5% 6% 38%	97806
Transparency	Day	46% 3 12% 24% 14% 2	101001
	Night	48% 3 11% 23% 14% 2	97689
Seeing	Day	16% 10% 29% 25% 15% 6%	15758
	Night	18% 9% 30% 30% 12% 1	25587

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	14% 14% 7% 12% 6% 5% 4 4 5% 6% 24%	2527
	11th to 20th	Day	14% 16% 6% 15% 6% 5% 4 6% 7% 4 17%	2530
	21st to end	Day	19% 24% 6% 12% 5% 3 3 2 3 5% 17%	2856
February	1st to 10th	Day	18% 12% 5% 9% 6% 5% 5% 4 5% 6% 26%	1786
	11th to 20th	Day	14% 11% 4 8% 6% 5% 4 3 5% 6% 32%	1848
	21st to end	Day	15% 14% 5% 10% 6% 4 4 4 5% 6% 28%	1570
March	1st to 10th	Day	18% 15% 4 7% 4 4 3 3 4 5% 33%	3120
	11th to 20th	Day	10% 7% 3 8% 5% 4 5% 4 7% 9% 38%	3249
	21st to end	Day	19% 12% 6% 11% 6% 6% 5% 4 4 6% 22%	4165
April	1st to 10th	Day	16% 13% 3 7% 5% 4 4 3 5% 7% 32%	2280
	11th to 20th	Day	16% 10% 3 6% 5% 4 4 3 5% 7% 37%	2254
	21st to end	Day	20% 8% 3 7% 5% 5% 5% 4 5% 6% 34%	2386
May	1st to 10th	Day	18% 8% 2 7% 5% 5% 5% 4 6% 9% 32%	4082
	11th to 20th	Day	15% 6% 2 7% 4 5% 4 3 6% 7% 40%	4221
	21st to end	Day	10% 6% 2 6% 5% 4 4 4 6% 9% 45%	4824
June	1st to 10th	Day	11% 6% 2 6% 4 4 4 5% 6% 8% 45%	2660
	11th to 20th	Day	9% 5% 1 6% 5% 4 5% 4 6% 9% 45%	2660
	21st to end	Day	10% 6% 2 6% 6% 6% 6% 5% 8% 8% 38%	2660
July	1st to 10th	Day	11% 7% 2 8% 5% 5% 6% 5% 7% 10% 33%	4440
	11th to 20th	Day	8% 4 2 5% 4 4 5% 5% 7% 10% 47%	4440
	21st to end	Day	9% 5% 2 7% 5% 5% 6% 5% 6% 9% 40%	4813
August	1st to 10th	Day	7% 5% 2 6% 4 4 5% 3 7% 9% 47%	4269
	11th to 20th	Day	9% 5% 2 6% 4 4 5% 5% 7% 9% 44%	3743
	21st to end	Day	7% 4 2 6% 4 4 4 4 6% 9% 48%	4180
September	1st to 10th	Day	11% 5% 2 5% 4 4 5% 4 6% 7% 47%	2280
	11th to 20th	Day	12% 5% 2 4 3 4 4 4 5% 8% 51%	2142
	21st to end	Day	11% 5% 2 7% 5% 4 4 4 6% 9% 43%	2090
October	1st to 10th	Day	11% 6% 3 7% 4 3 4 3 5% 6% 47%	2068
	11th to 20th	Day	18% 8% 2 6% 4 4 4 3 6% 7% 38%	1881
	21st to end	Day	20% 9% 3 7% 4 4 4 3 5% 7% 33%	1881
November	1st to 10th	Day	12% 8% 2 4 4 3 3 4 5% 7% 47%	1681
	11th to 20th	Day	17% 10% 4 7% 5% 3 4 3 6% 7% 35%	1710
	21st to end	Day	18% 11% 3 9% 4 3 4 3 4 5% 35%	1696
December	1st to 10th	Day	15% 15% 4 10% 5% 5% 5% 3 4 5% 29%	1520
	11th to 20th	Day	14% 13% 4 10% 6% 5% 5% 3 5% 6% 28%	1918
	21st to end	Day	22% 21% 8% 13% 5% 4 3 3 4 4 13%	2783
January	1st to 10th	Night	15% 15% 8% 11% 5% 4 3 3 4 4 27%	4428
	11th to 20th	Night	15% 18% 7% 13% 6% 4 5% 4 6% 3 18%	4440
	21st to end	Night	23% 18% 7% 10% 4 4 3 2 4 4 21%	4806
February	1st to 10th	Night	16% 15% 5% 8% 5% 5% 3 3 4 5% 31%	2393
	11th to 20th	Night	14% 11% 3 8% 5% 5% 4 4 4 7% 35%	2218
	21st to end	Night	18% 12% 4 9% 5% 4 3 2 5% 5% 33%	1884
March	1st to 10th	Night	18% 11% 3 7% 4 3 3 3 4 5% 38%	3733
	11th to 20th	Night	11% 6% 2 6% 4 4 5% 3 5% 7% 47%	3722
	21st to end	Night	19% 10% 5% 10% 6% 5% 5% 3 4 5% 27%	3470
April	1st to 10th	Night	14% 9% 3 6% 4 4 4 4 5% 8% 39%	1900
	11th to 20th	Night	18% 8% 3 6% 4 4 4 3 4 6% 40%	1875
	21st to end	Night	17% 8% 3 7% 4 4 5% 4 5% 6% 36%	1792
May	1st to 10th	Night	16% 8% 3 7% 5% 4 4 4 6% 9% 34%	2813
	11th to 20th	Night	14% 7% 2 6% 4 3 4 4 6% 10% 39%	2674
	21st to end	Night	10% 7% 2 6% 5% 4 4 4 5% 7% 44%	2743
June	1st to 10th	Night	10% 5% 3 6% 3 4 4 4 6% 7% 50%	1520
	11th to 20th	Night	8% 5% 2 7% 4 5% 4 3 6% 9% 47%	1520
	21st to end	Night	9% 7% 2 5% 6% 4 5% 4 7% 8% 42%	1520
July	1st to 10th	Night	11% 5% 3 6% 5% 5% 5% 4 7% 9% 41%	2530
	11th to 20th	Night	6% 4 2 5% 4 4 4 4 5% 7% 56%	2530
	21st to end	Night	4 5% 3 7% 5% 5% 5% 5% 8% 8% 46%	2750
August	1st to 10th	Night	6% 4 2 6% 4 5% 5% 4 7% 9% 49%	2662
	11th to 20th	Night	8% 4 2 4 3 4 4 4 6% 8% 52%	3070
	21st to end	Night	8% 4 2 5% 3 4 4 3 5% 9% 52%	3476
September	1st to 10th	Night	10% 5% 1 6% 3 3 4 3 5% 7% 54%	1900
	11th to 20th	Night	8% 4 2 4 3 4 4 3 6% 8% 55%	2019
	21st to end	Night	9% 5% 2 6% 4 6% 5% 4 6% 8% 44%	2090
October	1st to 10th	Night	11% 5% 3 5% 3 4 4 3 4 7% 52%	2109
	11th to 20th	Night	15% 8% 2 6% 4 3 3 2 4 6% 47%	2299
	21st to end	Night	20% 8% 3 7% 4 4 3 2 4 6% 38%	2717
November	1st to 10th	Night	11% 8% 3 6% 4 4 3 3 5% 6% 48%	2431
	11th to 20th	Night	14% 9% 4 9% 4 4 5% 3 5% 6% 38%	2470
	21st to end	Night	18% 10% 4 6% 5% 4 4 3 4 6% 37%	2479
December	1st to 10th	Night	16% 11% 4 9% 4 5% 4 3 5% 6% 32%	2660
	11th to 20th	Night	16% 15% 4 10% 6% 4 4 3 4 5% 32%	3279
	21st to end	Night	24% 18% 6% 11% 6% 4 4 3 4 4 16%	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	63% 2 12% 17% 6%	2528
	11th to 20th	Day	68% 2 9% 12% 9% 1	2530
	21st to end	Day	73% 1 7% 13% 5%	2856
February	1st to 10th	Day	59% 2 11% 17% 9% 2	1786
	11th to 20th	Day	53% 2 9% 24% 10% 2	1858
	21st to end	Day	58% 2 9% 21% 6% 2	1570
March	1st to 10th	Day	56% 1 9% 21% 11% 1	3120
	11th to 20th	Day	43% 2 11% 30% 13% 1	3249
	21st to end	Day	65% 2 13% 16% 3	4165
April	1st to 10th	Day	52% 3 10% 20% 14%	2280
	11th to 20th	Day	48% 3 11% 23% 12% 3	2254
	21st to end	Day	52% 2 12% 19% 12% 2	2386
May	1st to 10th	Day	50% 2 9% 28% 10%	4120
	11th to 20th	Day	44% 2 12% 30% 12% 1	4225
	21st to end	Day	37% 2 10% 24% 23% 4	4837
June	1st to 10th	Day	37% 4 11% 27% 19% 3	2660
	11th to 20th	Day	36% 3 11% 26% 21% 3	2660
	21st to end	Day	40% 5% 14% 23% 15% 3	2660
July	1st to 10th	Day	44% 5% 13% 22% 14% 2	4371
	11th to 20th	Day	31% 6% 16% 30% 16% 1	4365
	21st to end	Day	39% 6% 16% 18% 19% 3	4662
August	1st to 10th	Day	33% 5% 16% 31% 14% 1	4254
	11th to 20th	Day	34% 5% 12% 32% 16% 1	3779
	21st to end	Day	32% 5% 12% 28% 20% 3	4179
September	1st to 10th	Day	36% 4 11% 28% 17% 4	2280
	11th to 20th	Day	32% 3 10% 28% 22% 4	2142
	21st to end	Day	38% 4 8% 27% 21% 2	2090
October	1st to 10th	Day	38% 3 11% 27% 18% 2	2068
	11th to 20th	Day	47% 2 10% 23% 16% 1	1881
	21st to end	Day	51% 3 10% 23% 11% 2	1881
November	1st to 10th	Day	37% 2 15% 26% 17% 2	1681
	11th to 20th	Day	50% 2 12% 24% 12% 1	1710
	21st to end	Day	53% 3 10% 23% 11% 1	1696
December	1st to 10th	Day	59% 2 11% 19% 8% 1	1520
	11th to 20th	Day	59% 2 10% 21% 7% 1	1915
	21st to end	Day	77% 2 7% 10% 4	2783
January	1st to 10th	Night	63% 2 9% 17% 8% 1	4428
	11th to 20th	Night	70% 1 10% 12% 6%	4440
	21st to end	Night	69% 1 8% 15% 6%	4806
February	1st to 10th	Night	57% 2 10% 19% 10% 2	2393
	11th to 20th	Night	50% 2 9% 23% 14% 2	2219
	21st to end	Night	55% 3 8% 20% 11% 3	1884
March	1st to 10th	Night	50% 1 11% 26% 9% 3	3733
	11th to 20th	Night	39% 2 10% 29% 19% 2	3722
	21st to end	Night	61% 2 10% 21% 6%	3470
April	1st to 10th	Night	44% 3 12% 25% 14% 2	1900
	11th to 20th	Night	48% 2 7% 22% 17% 4	1875
	21st to end	Night	49% 4 10% 20% 15% 3	1792
May	1st to 10th	Night	48% 2 12% 23% 13% 2	2840
	11th to 20th	Night	42% 3 15% 28% 11%	2675
	21st to end	Night	40% 3 10% 21% 20% 6%	2751
June	1st to 10th	Night	34% 2 12% 27% 21% 4	1520
	11th to 20th	Night	34% 3 11% 25% 23% 3	1520
	21st to end	Night	39% 4 15% 22% 15% 4	1520
July	1st to 10th	Night	40% 4 15% 24% 12% 6%	2490
	11th to 20th	Night	28% 4 13% 28% 25% 2	2482
	21st to end	Night	34% 5% 16% 20% 20% 5%	2662
August	1st to 10th	Night	31% 5% 18% 29% 17% 1	2653
	11th to 20th	Night	29% 5% 15% 30% 20% 1	3099
	21st to end	Night	29% 5% 11% 33% 18% 3	3476
September	1st to 10th	Night	31% 4 11% 26% 24% 5%	1900
	11th to 20th	Night	28% 3 8% 30% 27% 4	2019
	21st to end	Night	37% 4 8% 29% 18% 3	2090
October	1st to 10th	Night	34% 4 9% 28% 23% 3	2109
	11th to 20th	Night	40% 2 7% 27% 22% 2	2299
	21st to end	Night	49% 2 9% 23% 16% 2	2717
November	1st to 10th	Night	38% 3 9% 29% 19% 3	2431
	11th to 20th	Night	48% 2 11% 23% 15% 2	2470
	21st to end	Night	51% 2 10% 25% 12%	2479
December	1st to 10th	Night	54% 2 12% 22% 10% 1	2660
	11th to 20th	Night	57% 1 10% 19% 12% 1	3281
	21st to end	Night	74% 2 8% 11% 5%	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	21% 12% 34% 26% 6% 1	270
	11th to 20th	Day	26% 17% 34% 16% 5% 1	270
	21st to end	Day	23% 14% 35% 22% 6%	297
February	1st to 10th	Day	25% 17% 37% 16% 4	270
	11th to 20th	Day	24% 13% 37% 21% 4	270
	21st to end	Day	24% 19% 40% 13% 4	225
March	1st to 10th	Day	21% 22% 34% 20% 2	270
	11th to 20th	Day	21% 17% 33% 21% 6%	308
	21st to end	Day	30% 13% 30% 18% 6% 2	506
April	1st to 10th	Day	22% 13% 33% 23% 8% 1	460
	11th to 20th	Day	20% 16% 31% 19% 11% 3	452
	21st to end	Day	21% 17% 33% 20% 7% 2	460
May	1st to 10th	Day	22% 12% 32% 23% 9% 3	463
	11th to 20th	Day	20% 8% 31% 23% 14% 4	562
	21st to end	Day	13% 9% 31% 23% 16% 8%	734
June	1st to 10th	Day	10% 8% 30% 29% 19% 5%	680
	11th to 20th	Day	11% 5% 30% 31% 18% 5%	680
	21st to end	Day	13% 8% 30% 30% 14% 5%	680
July	1st to 10th	Day	9% 5% 21% 28% 22% 15%	671
	11th to 20th	Day	9% 5% 23% 31% 20% 11%	668
	21st to end	Day	8% 3 22% 35% 23% 9%	739
August	1st to 10th	Day	9% 3 16% 32% 27% 13%	587
	11th to 20th	Day	10% 4 19% 28% 24% 15%	479
	21st to end	Day	7% 2 17% 36% 25% 13%	539
September	1st to 10th	Day	11% 6% 20% 31% 23% 9%	490
	11th to 20th	Day	11% 5% 14% 27% 30% 12%	490
	21st to end	Day	13% 7% 26% 27% 19% 8%	490
October	1st to 10th	Day	13% 6% 29% 28% 19% 5%	468
	11th to 20th	Day	20% 18% 31% 21% 9% 1	300
	21st to end	Day	31% 11% 35% 18% 5%	330
November	1st to 10th	Day	15% 13% 36% 23% 9% 5%	273
	11th to 20th	Day	23% 14% 36% 16% 9% 1	270
	21st to end	Day	24% 11% 37% 22% 6%	270
December	1st to 10th	Day	17% 17% 39% 18% 8% 1	270
	11th to 20th	Day	20% 15% 37% 22% 6%	270
	21st to end	Day	24% 21% 39% 13% 2	297
January	1st to 10th	Night	20% 15% 38% 23% 4	950
	11th to 20th	Night	24% 14% 36% 22% 4	950
	21st to end	Night	22% 12% 34% 27% 4	1045
February	1st to 10th	Night	25% 12% 37% 23% 3	873
	11th to 20th	Night	20% 13% 36% 27% 4	743
	21st to end	Night	24% 15% 38% 20% 3	628
March	1st to 10th	Night	22% 13% 35% 24% 5%	760
	11th to 20th	Night	18% 11% 39% 26% 6% 1	760
	21st to end	Night	26% 9% 35% 23% 7%	631
April	1st to 10th	Night	19% 10% 40% 25% 6% 1	570
	11th to 20th	Night	21% 12% 33% 25% 8%	563
	21st to end	Night	20% 11% 32% 28% 8% 1	570
May	1st to 10th	Night	19% 6% 35% 32% 8%	570
	11th to 20th	Night	17% 6% 29% 35% 13% 1	561
	21st to end	Night	11% 5% 27% 37% 19% 1	617
June	1st to 10th	Night	11% 4 27% 44% 15%	570
	11th to 20th	Night	10% 4 28% 42% 15% 2	570
	21st to end	Night	11% 4 27% 38% 18% 1	570
July	1st to 10th	Night	9% 2 16% 44% 26% 4	555
	11th to 20th	Night	7% 3 19% 40% 28% 3	552
	21st to end	Night	5% 1 18% 47% 28% 1	624
August	1st to 10th	Night	5% 2 11% 48% 31% 4	567
	11th to 20th	Night	8% 2 12% 41% 31% 5%	564
	21st to end	Night	8% 2 17% 38% 32% 3	627
September	1st to 10th	Night	11% 3 16% 40% 27% 4	570
	11th to 20th	Night	9% 4 16% 39% 28% 4	689
	21st to end	Night	12% 6% 24% 33% 22% 3	760
October	1st to 10th	Night	13% 6% 24% 36% 20% 1	760
	11th to 20th	Night	19% 13% 31% 27% 10%	760
	21st to end	Night	24% 13% 31% 24% 8%	836
November	1st to 10th	Night	15% 11% 38% 25% 10% 1	748
	11th to 20th	Night	19% 16% 33% 26% 6%	760
	21st to end	Night	22% 12% 35% 24% 7%	769
December	1st to 10th	Night	23% 13% 35% 24% 5%	950
	11th to 20th	Night	24% 11% 34% 26% 5%	950
	21st to end	Night	29% 13% 33% 23% 2	1045

Page generated at 2024-10-30 12:19:24. Version ac07

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