Peoria
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Peoria clear sky chart from 2005-11-06 to 2024-03-28.

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% 4 7% 6% 3 5% 4 5% 7% 37%	78753
	Night	14% 9% 4 6% 5% 3 4 4 5% 6% 39%	81293
Transparency	Day	46% 5% 12% 23% 13% 2	78454
	Night	46% 4 11% 23% 14% 2	81113
Seeing	Day	18% 12% 29% 24% 13% 4	14814
	Night	18% 10% 31% 29% 11% 1	24865

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	11% 14% 8% 14% 8% 4 4 4 4 6% 24%	2527
	11th to 20th	Day	13% 12% 4 12% 9% 4 7% 6% 8% 4 21%	2530
	21st to end	Day	18% 20% 11% 8% 7% 3 4 3 3 5% 18%	3083
February	1st to 10th	Day	16% 12% 6% 10% 6% 3 5% 3 3 5% 31%	1710
	11th to 20th	Day	15% 9% 5% 7% 8% 3 5% 5% 4 7% 33%	1829
	21st to end	Day	14% 14% 6% 9% 6% 2 4 4 4 5% 32%	1570
March	1st to 10th	Day	16% 13% 5% 6% 5% 4 3 3 4 5% 34%	1900
	11th to 20th	Day	13% 9% 3 8% 6% 3 4 5% 7% 8% 34%	2039
	21st to end	Day	21% 12% 4 8% 6% 3 5% 4 5% 6% 25%	2416
April	1st to 10th	Day	15% 9% 4 7% 6% 3 4 4 5% 6% 36%	2160
	11th to 20th	Day	17% 9% 4 4 6% 3 4 5% 4 7% 38%	2134
	21st to end	Day	20% 8% 3 6% 6% 3 4 4 5% 6% 34%	2160
May	1st to 10th	Day	18% 7% 3 6% 6% 3 5% 5% 6% 8% 33%	2327
	11th to 20th	Day	19% 7% 2 6% 6% 3 5% 4 5% 7% 36%	2474
	21st to end	Day	15% 6% 2 6% 5% 4 6% 6% 7% 8% 35%	2725
June	1st to 10th	Day	9% 4 3 5% 6% 4 5% 5% 6% 9% 45%	2520
	11th to 20th	Day	8% 4 3 6% 6% 3 6% 5% 5% 7% 47%	2520
	21st to end	Day	10% 5% 4 6% 5% 4 6% 6% 6% 8% 40%	2520
July	1st to 10th	Day	8% 4 2 5% 6% 4 5% 6% 7% 10% 44%	2520
	11th to 20th	Day	8% 5% 2 4 4 3 5% 6% 7% 10% 46%	2520
	21st to end	Day	7% 4 3 5% 6% 4 5% 4 7% 9% 45%	2743
August	1st to 10th	Day	7% 5% 2 5% 5% 4 5% 5% 8% 10% 43%	2364
	11th to 20th	Day	8% 5% 2 5% 6% 3 5% 4 6% 9% 46%	2125
	21st to end	Day	7% 4 2 4 4 3 5% 6% 8% 8% 49%	2376
September	1st to 10th	Day	11% 6% 2 5% 4 4 4 4 5% 8% 47%	2160
	11th to 20th	Day	11% 3 2 4 4 3 3 5% 6% 7% 52%	2104
	21st to end	Day	8% 5% 3 5% 5% 3 4 5% 6% 8% 48%	1980
October	1st to 10th	Day	13% 6% 3 4 4 3 4 4 5% 5% 49%	1845
	11th to 20th	Day	18% 8% 2 6% 5% 3 4 3 4 6% 42%	1800
	21st to end	Day	21% 9% 3 5% 3 2 3 3 4 6% 38%	1868
November	1st to 10th	Day	11% 7% 2 5% 4 3 4 4 4 8% 48%	1672
	11th to 20th	Day	18% 9% 3 6% 5% 3 4 4 4 6% 38%	1710
	21st to end	Day	17% 12% 3 7% 5% 3 3 3 4 4 38%	1601
December	1st to 10th	Day	15% 11% 5% 6% 7% 3 5% 5% 4 6% 33%	1520
	11th to 20th	Day	15% 12% 4 10% 6% 4 5% 4 4 6% 30%	1918
	21st to end	Day	23% 20% 8% 11% 5% 3 3 3 3 5% 17%	2783
January	1st to 10th	Night	14% 13% 5% 10% 6% 3 4 4 4 5% 30%	4428
	11th to 20th	Night	13% 18% 6% 10% 6% 4 6% 5% 6% 4 22%	4440
	21st to end	Night	21% 17% 7% 9% 6% 3 3 3 3 6% 22%	4582
February	1st to 10th	Night	15% 12% 5% 7% 6% 4 5% 4 4 6% 32%	2470
	11th to 20th	Night	14% 10% 4 8% 5% 3 5% 4 4 7% 37%	2236
	21st to end	Night	17% 11% 5% 7% 5% 2 3 4 4 5% 38%	1884
March	1st to 10th	Night	14% 11% 5% 7% 5% 3 4 4 4 6% 38%	2280
	11th to 20th	Night	14% 8% 5% 6% 5% 2 4 4 5% 8% 39%	2157
	21st to end	Night	20% 10% 5% 7% 5% 3 4 4 5% 6% 30%	2093
April	1st to 10th	Night	14% 9% 4 6% 4 3 4 4 6% 7% 40%	1800
	11th to 20th	Night	16% 8% 3 5% 6% 3 4 5% 4 6% 42%	1775
	21st to end	Night	19% 7% 3 6% 7% 2 3 4 5% 7% 37%	1800
May	1st to 10th	Night	15% 8% 3 7% 4 3 4 5% 5% 9% 36%	1630
	11th to 20th	Night	16% 7% 3 5% 6% 2 4 5% 5% 6% 42%	1417
	21st to end	Night	11% 5% 3 7% 6% 4 6% 5% 6% 9% 39%	1551
June	1st to 10th	Night	10% 5% 3 4 3 2 4 4 6% 8% 51%	1440
	11th to 20th	Night	7% 5% 2 6% 5% 4 4 5% 5% 8% 48%	1440
	21st to end	Night	9% 5% 3 5% 5% 3 6% 5% 7% 8% 44%	1440
July	1st to 10th	Night	8% 4 2 4 4 3 5% 5% 6% 12% 49%	1440
	11th to 20th	Night	5% 3 2 3 5% 1 4 5% 6% 10% 55%	1440
	21st to end	Night	4 4 2 5% 4 3 5% 6% 6% 9% 52%	1575
August	1st to 10th	Night	6% 3 1 4 5% 3 5% 5% 6% 10% 52%	1570
	11th to 20th	Night	6% 3 2 5% 5% 3 5% 4 5% 8% 55%	1774
	21st to end	Night	6% 4 2 4 4 2 4 4 6% 7% 57%	1980
September	1st to 10th	Night	11% 5% 2 4 5% 2 3 4 4 5% 55%	1800
	11th to 20th	Night	10% 3 2 4 4 2 4 4 4 7% 55%	1837
	21st to end	Night	7% 5% 2 5% 5% 3 4 6% 6% 8% 49%	1980
October	1st to 10th	Night	11% 4 2 5% 4 3 4 4 4 6% 52%	2113
	11th to 20th	Night	16% 5% 2 4 4 2 3 4 5% 6% 48%	2160
	21st to end	Night	18% 9% 3 6% 5% 3 4 4 5% 5% 39%	2488
November	1st to 10th	Night	11% 5% 3 4 4 2 3 4 4 6% 52%	2406
	11th to 20th	Night	13% 8% 3 6% 6% 3 4 4 4 6% 43%	2470
	21st to end	Night	18% 9% 4 6% 5% 3 3 3 4 6% 39%	2574
December	1st to 10th	Night	15% 12% 4 7% 5% 3 4 4 5% 6% 35%	2660
	11th to 20th	Night	16% 11% 5% 8% 5% 3 4 3 4 6% 35%	3279
	21st to end	Night	23% 19% 8% 10% 6% 3 4 3 3 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% 3 9% 18% 6%	2528
	11th to 20th	Day	64% 4 11% 13% 8%	2530
	21st to end	Day	70% 3 9% 12% 5%	3083
February	1st to 10th	Day	58% 3 12% 17% 8% 2	1710
	11th to 20th	Day	51% 5% 11% 21% 11% 1	1839
	21st to end	Day	55% 4 10% 21% 8% 2	1570
March	1st to 10th	Day	53% 3 12% 22% 9% 1	1900
	11th to 20th	Day	47% 5% 14% 23% 9% 1	2039
	21st to end	Day	59% 4 12% 19% 5% 1	2416
April	1st to 10th	Day	49% 4 11% 23% 12%	2160
	11th to 20th	Day	47% 4 10% 24% 13% 2	2134
	21st to end	Day	51% 5% 11% 19% 12% 2	2160
May	1st to 10th	Day	49% 6% 14% 23% 9%	2327
	11th to 20th	Day	48% 5% 12% 22% 12% 1	2478
	21st to end	Day	44% 8% 13% 19% 15% 2	2725
June	1st to 10th	Day	34% 7% 13% 29% 15% 3	2520
	11th to 20th	Day	35% 6% 11% 24% 22% 3	2520
	21st to end	Day	40% 8% 13% 22% 15% 3	2520
July	1st to 10th	Day	34% 7% 15% 26% 15% 4	2451
	11th to 20th	Day	32% 6% 16% 30% 14% 2	2445
	21st to end	Day	33% 6% 15% 29% 15% 2	2591
August	1st to 10th	Day	33% 7% 17% 30% 12% 2	2349
	11th to 20th	Day	34% 5% 14% 30% 16% 1	2125
	21st to end	Day	30% 6% 14% 26% 20% 4	2376
September	1st to 10th	Day	36% 5% 11% 24% 19% 5%	2160
	11th to 20th	Day	31% 4 12% 26% 23% 4	2104
	21st to end	Day	33% 5% 10% 29% 21% 2	1980
October	1st to 10th	Day	36% 4 10% 29% 19% 3	1845
	11th to 20th	Day	44% 3 9% 24% 19% 1	1800
	21st to end	Day	48% 3 11% 23% 12% 3	1868
November	1st to 10th	Day	35% 4 15% 25% 16% 3	1672
	11th to 20th	Day	47% 3 11% 24% 13% 1	1710
	21st to end	Day	51% 3 12% 24% 10%	1601
December	1st to 10th	Day	53% 4 13% 22% 8% 1	1520
	11th to 20th	Day	55% 4 9% 24% 7% 1	1915
	21st to end	Day	72% 4 8% 11% 4	2783
January	1st to 10th	Night	56% 3 12% 20% 8%	4428
	11th to 20th	Night	65% 2 10% 15% 7% 1	4440
	21st to end	Night	66% 2 10% 16% 5%	4582
February	1st to 10th	Night	54% 4 11% 18% 11% 2	2470
	11th to 20th	Night	48% 4 11% 24% 12% 1	2237
	21st to end	Night	49% 3 8% 24% 13% 2	1884
March	1st to 10th	Night	48% 4 12% 24% 12% 1	2280
	11th to 20th	Night	44% 4 11% 24% 14% 3	2157
	21st to end	Night	56% 5% 11% 19% 8% 1	2093
April	1st to 10th	Night	43% 4 11% 25% 14% 3	1800
	11th to 20th	Night	44% 4 8% 25% 14% 5%	1775
	21st to end	Night	47% 5% 11% 21% 13% 4	1800
May	1st to 10th	Night	45% 6% 12% 24% 13% 1	1630
	11th to 20th	Night	43% 5% 13% 22% 16% 1	1418
	21st to end	Night	41% 6% 14% 19% 17% 3	1552
June	1st to 10th	Night	30% 5% 14% 27% 19% 5%	1440
	11th to 20th	Night	33% 5% 12% 24% 21% 5%	1440
	21st to end	Night	35% 6% 14% 23% 19% 3	1440
July	1st to 10th	Night	30% 6% 13% 32% 15% 4	1400
	11th to 20th	Night	25% 5% 15% 31% 22% 3	1392
	21st to end	Night	25% 7% 14% 29% 20% 4	1487
August	1st to 10th	Night	26% 7% 17% 34% 15% 2	1561
	11th to 20th	Night	29% 4 12% 31% 22% 2	1774
	21st to end	Night	25% 6% 12% 30% 21% 6%	1980
September	1st to 10th	Night	31% 4 10% 28% 22% 6%	1800
	11th to 20th	Night	29% 4 10% 28% 24% 5%	1837
	21st to end	Night	31% 5% 10% 27% 22% 4	1980
October	1st to 10th	Night	33% 4 10% 24% 23% 4	2113
	11th to 20th	Night	36% 4 9% 27% 21% 3	2160
	21st to end	Night	47% 3 10% 22% 16% 2	2488
November	1st to 10th	Night	33% 5% 12% 27% 19% 4	2406
	11th to 20th	Night	42% 3 12% 24% 16% 2	2470
	21st to end	Night	48% 3 10% 25% 13% 1	2574
December	1st to 10th	Night	50% 3 13% 23% 10% 1	2660
	11th to 20th	Night	51% 4 11% 25% 9% 1	3281
	21st to end	Night	73% 4 7% 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	26% 20% 31% 19% 4	270
	11th to 20th	Day	31% 21% 36% 10% 2	270
	21st to end	Day	23% 25% 32% 16% 4	297
February	1st to 10th	Day	26% 20% 40% 12% 2	270
	11th to 20th	Day	25% 26% 30% 14% 4	270
	21st to end	Day	24% 23% 41% 9% 2	225
March	1st to 10th	Day	29% 29% 30% 10% 1	270
	11th to 20th	Day	28% 24% 34% 12% 2	270
	21st to end	Day	34% 14% 30% 16% 5% 1	446
April	1st to 10th	Day	24% 14% 34% 23% 4 1	420
	11th to 20th	Day	21% 17% 33% 17% 11% 1	412
	21st to end	Day	26% 16% 31% 19% 6% 1	420
May	1st to 10th	Day	23% 14% 34% 18% 7% 2	423
	11th to 20th	Day	23% 12% 31% 23% 9% 3	620
	21st to end	Day	15% 10% 30% 25% 13% 8%	679
June	1st to 10th	Day	11% 5% 30% 29% 20% 5%	630
	11th to 20th	Day	9% 8% 29% 33% 19% 3	630
	21st to end	Day	12% 10% 30% 30% 14% 4	630
July	1st to 10th	Day	10% 3 20% 32% 21% 14%	621
	11th to 20th	Day	11% 3 24% 33% 23% 7%	618
	21st to end	Day	10% 3 22% 37% 24% 4	684
August	1st to 10th	Day	8% 3 22% 35% 23% 9%	626
	11th to 20th	Day	10% 3 23% 25% 26% 13%	439
	21st to end	Day	7% 5% 19% 30% 30% 8%	495
September	1st to 10th	Day	13% 7% 20% 31% 24% 4	450
	11th to 20th	Day	11% 4 19% 33% 25% 8%	450
	21st to end	Day	10% 12% 25% 25% 23% 6%	450
October	1st to 10th	Day	17% 12% 29% 28% 12% 4	315
	11th to 20th	Day	21% 23% 36% 15% 6%	270
	21st to end	Day	35% 15% 33% 13% 3	297
November	1st to 10th	Day	13% 17% 39% 21% 8% 2	270
	11th to 20th	Day	26% 19% 34% 16% 5% 1	270
	21st to end	Day	26% 12% 44% 18% 1	270
December	1st to 10th	Day	16% 25% 36% 16% 4 3	270
	11th to 20th	Day	23% 17% 38% 19% 3	270
	21st to end	Day	27% 28% 31% 13% 1	297
January	1st to 10th	Night	19% 15% 39% 21% 6%	950
	11th to 20th	Night	22% 15% 38% 21% 5%	950
	21st to end	Night	22% 14% 35% 25% 3	1045
February	1st to 10th	Night	23% 12% 37% 23% 4	950
	11th to 20th	Night	22% 15% 35% 25% 3	761
	21st to end	Night	25% 18% 38% 17% 2	628
March	1st to 10th	Night	21% 14% 39% 21% 5%	760
	11th to 20th	Night	21% 12% 32% 29% 6%	637
	21st to end	Night	27% 10% 36% 21% 6%	615
April	1st to 10th	Night	19% 13% 37% 25% 6%	540
	11th to 20th	Night	20% 14% 30% 26% 10%	533
	21st to end	Night	23% 11% 31% 28% 7% 1	540
May	1st to 10th	Night	20% 8% 33% 31% 8% 1	540
	11th to 20th	Night	19% 5% 31% 35% 9% 1	531
	21st to end	Night	13% 4 28% 35% 18% 2	584
June	1st to 10th	Night	11% 3 26% 44% 15% 1	540
	11th to 20th	Night	10% 2 29% 43% 16% 1	540
	21st to end	Night	10% 4 29% 39% 17% 1	540
July	1st to 10th	Night	9% 2 14% 39% 32% 4	525
	11th to 20th	Night	5% 3 21% 43% 26% 2	522
	21st to end	Night	6% 1 16% 47% 29% 1	591
August	1st to 10th	Night	8% 1 16% 44% 25% 6%	537
	11th to 20th	Night	7% 1 15% 41% 30% 6%	534
	21st to end	Night	8% 2 19% 38% 32% 2	594
September	1st to 10th	Night	13% 3 19% 37% 26% 3	540
	11th to 20th	Night	11% 3 19% 36% 25% 5%	577
	21st to end	Night	9% 8% 24% 33% 23% 3	720
October	1st to 10th	Night	13% 7% 29% 32% 17% 2	720
	11th to 20th	Night	19% 12% 29% 28% 11% 1	720
	21st to end	Night	25% 12% 34% 22% 7%	792
November	1st to 10th	Night	15% 11% 40% 25% 9% 1	740
	11th to 20th	Night	19% 16% 33% 26% 6%	760
	21st to end	Night	22% 14% 36% 23% 5%	864
December	1st to 10th	Night	21% 14% 36% 23% 5%	950
	11th to 20th	Night	24% 12% 33% 26% 6%	950
	21st to end	Night	31% 14% 31% 22% 2	1045

Page generated at 2024-03-24 22:36:59. Version ac07

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