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 2024-11-04.

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	13% 9% 3 7% 5% 4 4 4 6% 7% 38%	101357
	Night	13% 10% 3 7% 4 4 4 3 5% 7% 40%	97740
Transparency	Day	43% 5% 12% 23% 15% 2	104922
	Night	43% 4 11% 24% 16% 2	102316
Seeing	Day	17% 12% 29% 24% 13% 4	15758
	Night	18% 10% 31% 29% 11% 1	25578

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% 15% 7% 15% 6% 5% 4 3 4 6% 24%	2527
	11th to 20th	Day	13% 12% 4 14% 7% 6% 6% 5% 8% 4 21%	2530
	21st to end	Day	18% 21% 10% 9% 6% 4 3 2 3 5% 18%	3083
February	1st to 10th	Day	16% 13% 6% 10% 5% 6% 3 2 3 5% 30%	1710
	11th to 20th	Day	15% 10% 4 8% 7% 5% 4 4 4 7% 33%	1829
	21st to end	Day	14% 15% 5% 9% 5% 4 4 3 4 5% 32%	1570
March	1st to 10th	Day	16% 17% 4 7% 4 4 3 2 4 4 35%	3120
	11th to 20th	Day	9% 7% 2 7% 4 4 4 4 7% 7% 44%	3403
	21st to end	Day	20% 12% 4 10% 5% 4 5% 3 5% 6% 26%	4095
April	1st to 10th	Day	15% 11% 3 8% 5% 4 4 3 5% 6% 36%	2280
	11th to 20th	Day	16% 10% 3 6% 5% 4 4 4 4 6% 38%	2254
	21st to end	Day	19% 8% 3 7% 5% 4 4 4 5% 6% 34%	2280
May	1st to 10th	Day	16% 7% 3 7% 5% 5% 4 4 7% 9% 33%	4069
	11th to 20th	Day	17% 7% 2 7% 4 4 4 3 5% 7% 40%	4394
	21st to end	Day	11% 6% 2 6% 4 5% 4 4 6% 8% 45%	4824
June	1st to 10th	Day	9% 5% 2 6% 5% 5% 5% 4 6% 9% 45%	2660
	11th to 20th	Day	7% 5% 2 7% 5% 5% 5% 4 6% 8% 47%	2660
	21st to end	Day	10% 7% 3 7% 5% 5% 6% 5% 6% 8% 40%	2660
July	1st to 10th	Day	11% 6% 3 6% 5% 5% 6% 5% 8% 10% 35%	4440
	11th to 20th	Day	6% 5% 2 5% 4 4 5% 4 7% 10% 48%	4440
	21st to end	Day	8% 5% 2 6% 5% 6% 5% 5% 8% 10% 40%	4813
August	1st to 10th	Day	7% 5% 2 6% 5% 5% 5% 4 7% 10% 45%	4168
	11th to 20th	Day	10% 6% 3 6% 5% 5% 5% 4 8% 9% 40%	3729
	21st to end	Day	5% 4 2 6% 4 4 5% 4 7% 9% 49%	4180
September	1st to 10th	Day	11% 6% 2 5% 3 5% 4 3 5% 8% 49%	2280
	11th to 20th	Day	11% 4 2 5% 4 4 3 4 6% 7% 52%	2220
	21st to end	Day	9% 6% 3 6% 4 3 4 4 6% 8% 47%	2090
October	1st to 10th	Day	12% 6% 3 5% 3 4 4 3 5% 5% 51%	1947
	11th to 20th	Day	17% 8% 2 7% 4 4 3 2 4 6% 44%	1900
	21st to end	Day	20% 9% 3 6% 2 3 4 3 4 6% 39%	1971
November	1st to 10th	Day	11% 7% 2 6% 3 4 4 3 5% 8% 48%	1699
	11th to 20th	Day	18% 10% 2 7% 4 3 5% 3 4 6% 38%	1710
	21st to end	Day	17% 13% 2 8% 4 3 3 2 4 4 38%	1601
December	1st to 10th	Day	15% 11% 4 8% 6% 4 5% 3 5% 6% 33%	1520
	11th to 20th	Day	15% 13% 4 11% 5% 5% 5% 3 4 6% 29%	1918
	21st to end	Day	23% 20% 8% 12% 4 4 3 2 3 4 17%	2783
January	1st to 10th	Night	14% 14% 5% 11% 5% 4 4 3 4 5% 30%	4428
	11th to 20th	Night	13% 19% 6% 11% 5% 6% 5% 4 6% 4 22%	4440
	21st to end	Night	21% 18% 7% 10% 5% 4 3 2 3 6% 22%	4582
February	1st to 10th	Night	15% 13% 5% 8% 5% 5% 4 3 4 6% 31%	2470
	11th to 20th	Night	14% 11% 3 9% 5% 4 5% 2 4 7% 37%	2236
	21st to end	Night	16% 12% 4 8% 4 3 3 3 4 5% 38%	1884
March	1st to 10th	Night	17% 13% 3 6% 4 3 3 3 4 5% 38%	3733
	11th to 20th	Night	11% 7% 3 5% 4 3 4 3 5% 7% 48%	3586
	21st to end	Night	19% 11% 5% 9% 5% 5% 4 3 5% 5% 28%	3535
April	1st to 10th	Night	15% 11% 2 6% 3 4 4 4 5% 6% 40%	1900
	11th to 20th	Night	15% 9% 2 6% 5% 4 4 3 4 6% 42%	1875
	21st to end	Night	19% 7% 2 7% 6% 3 3 3 5% 7% 38%	1900
May	1st to 10th	Night	17% 9% 3 8% 4 5% 4 4 6% 9% 32%	2823
	11th to 20th	Night	14% 7% 2 6% 4 4 5% 4 6% 8% 40%	2507
	21st to end	Night	9% 7% 3 6% 4 4 4 4 7% 8% 45%	2743
June	1st to 10th	Night	10% 5% 2 4 3 3 4 3 7% 8% 50%	1520
	11th to 20th	Night	7% 5% 2 6% 4 5% 4 4 5% 8% 48%	1520
	21st to end	Night	9% 5% 2 7% 4 4 5% 4 7% 9% 44%	1520
July	1st to 10th	Night	12% 5% 2 7% 4 5% 5% 4 5% 10% 40%	2530
	11th to 20th	Night	4 3 2 5% 4 3 4 3 6% 9% 57%	2530
	21st to end	Night	6% 5% 2 6% 4 5% 5% 5% 7% 9% 46%	2750
August	1st to 10th	Night	6% 4 2 4 4 3 4 4 6% 10% 53%	2767
	11th to 20th	Night	5% 4 2 6% 4 4 5% 4 6% 8% 52%	3098
	21st to end	Night	5% 4 2 5% 3 4 4 4 7% 9% 53%	3476
September	1st to 10th	Night	10% 5% 2 5% 4 3 3 3 4 6% 57%	1900
	11th to 20th	Night	9% 4 2 4 4 3 4 3 5% 7% 55%	1940
	21st to end	Night	8% 6% 2 6% 4 4 4 4 6% 8% 48%	2090
October	1st to 10th	Night	10% 4 2 5% 3 4 4 3 4 6% 54%	2231
	11th to 20th	Night	15% 6% 2 4 3 3 3 3 5% 6% 49%	2280
	21st to end	Night	18% 9% 3 7% 4 4 4 3 5% 5% 39%	2627
November	1st to 10th	Night	11% 6% 3 4 4 3 3 3 5% 6% 52%	2452
	11th to 20th	Night	13% 9% 3 7% 5% 4 4 3 4 6% 42%	2470
	21st to end	Night	17% 10% 4 7% 4 4 3 3 4 6% 38%	2574
December	1st to 10th	Night	14% 13% 4 8% 5% 4 4 3 5% 6% 35%	2660
	11th to 20th	Night	15% 12% 4 9% 4 4 4 3 4 6% 35%	3279
	21st to end	Night	23% 20% 8% 10% 5% 4 4 2 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	54% 3 10% 19% 13% 2	3120
	11th to 20th	Day	37% 5% 14% 28% 15% 1	3403
	21st to end	Day	57% 5% 16% 18% 3 1	4095
April	1st to 10th	Day	49% 4 11% 23% 12%	2280
	11th to 20th	Day	47% 4 10% 24% 13% 3	2254
	21st to end	Day	50% 5% 11% 19% 13% 2	2280
May	1st to 10th	Day	46% 6% 14% 24% 10% 1	4107
	11th to 20th	Day	44% 4 12% 30% 9%	4398
	21st to end	Day	35% 7% 11% 22% 22% 2	4837
June	1st to 10th	Day	34% 6% 13% 29% 15% 3	2660
	11th to 20th	Day	34% 6% 10% 25% 22% 3	2660
	21st to end	Day	40% 7% 13% 22% 16% 3	2660
July	1st to 10th	Day	42% 6% 13% 24% 13% 2	4371
	11th to 20th	Day	30% 5% 16% 30% 18% 1	4365
	21st to end	Day	35% 7% 19% 21% 16% 2	4662
August	1st to 10th	Day	31% 6% 19% 31% 12% 1	4153
	11th to 20th	Day	38% 5% 15% 26% 16% 1	3765
	21st to end	Day	30% 6% 14% 31% 16% 4	4179
September	1st to 10th	Day	34% 5% 10% 25% 21% 5%	2280
	11th to 20th	Day	30% 4 11% 26% 24% 5%	2220
	21st to end	Day	34% 5% 10% 29% 21% 2	2090
October	1st to 10th	Day	23% 3 6% 27% 38% 3	3233
	11th to 20th	Day	29% 2 9% 22% 34% 4	3140
	21st to end	Day	42% 3 8% 25% 19% 3	3222
November	1st to 10th	Day	35% 4 15% 26% 16% 3	1699
	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	49% 4 10% 25% 12% 1	3733
	11th to 20th	Night	36% 4 10% 29% 18% 3	3586
	21st to end	Night	57% 5% 12% 19% 6% 1	3535
April	1st to 10th	Night	43% 4 11% 25% 14% 3	1900
	11th to 20th	Night	43% 4 8% 25% 15% 5%	1875
	21st to end	Night	46% 4 11% 21% 14% 3	1900
May	1st to 10th	Night	48% 5% 12% 21% 12% 1	2850
	11th to 20th	Night	41% 6% 15% 28% 10% 1	2508
	21st to end	Night	35% 6% 13% 21% 22% 3	2751
June	1st to 10th	Night	30% 5% 15% 27% 19% 5%	1520
	11th to 20th	Night	33% 5% 12% 25% 22% 4	1520
	21st to end	Night	35% 6% 14% 23% 18% 3	1520
July	1st to 10th	Night	40% 6% 13% 27% 13% 2	2490
	11th to 20th	Night	23% 5% 13% 31% 26% 2	2482
	21st to end	Night	32% 8% 16% 22% 18% 4	2662
August	1st to 10th	Night	24% 6% 18% 32% 18% 2	2758
	11th to 20th	Night	30% 4 14% 33% 18% 1	3128
	21st to end	Night	26% 6% 14% 35% 16% 3	3476
September	1st to 10th	Night	29% 4 10% 27% 25% 5%	1900
	11th to 20th	Night	29% 4 10% 27% 25% 5%	1940
	21st to end	Night	33% 5% 10% 27% 21% 4	2090
October	1st to 10th	Night	23% 3 6% 28% 36% 4	3725
	11th to 20th	Night	25% 3 8% 24% 35% 5%	3779
	21st to end	Night	38% 3 10% 23% 22% 4	4326
November	1st to 10th	Night	33% 5% 12% 27% 20% 4	2452
	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% 31% 15% 5% 1	462
April	1st to 10th	Day	26% 14% 34% 22% 3 1	460
	11th to 20th	Day	22% 17% 33% 17% 10% 1	452
	21st to end	Day	26% 17% 32% 19% 6% 1	460
May	1st to 10th	Day	22% 14% 35% 20% 7% 2	463
	11th to 20th	Day	22% 11% 31% 23% 9% 3	670
	21st to end	Day	15% 11% 30% 25% 13% 7%	734
June	1st to 10th	Day	11% 6% 30% 28% 19% 5%	680
	11th to 20th	Day	8% 7% 30% 34% 17% 3	680
	21st to end	Day	12% 10% 33% 29% 13% 4	680
July	1st to 10th	Day	11% 4 22% 31% 20% 13%	671
	11th to 20th	Day	10% 3 24% 33% 22% 7%	668
	21st to end	Day	9% 3 22% 36% 25% 4	739
August	1st to 10th	Day	7% 4 23% 35% 23% 8%	676
	11th to 20th	Day	11% 3 25% 25% 24% 12%	479
	21st to end	Day	7% 4 19% 32% 30% 8%	539
September	1st to 10th	Day	12% 7% 20% 32% 24% 4	490
	11th to 20th	Day	10% 4 18% 34% 26% 8%	490
	21st to end	Day	12% 12% 25% 24% 22% 5%	490
October	1st to 10th	Day	16% 12% 27% 28% 13% 4	347
	11th to 20th	Day	19% 22% 33% 18% 6% 1	300
	21st to end	Day	33% 15% 33% 15% 3	330
November	1st to 10th	Day	13% 17% 39% 21% 8% 2	279
	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	26% 10% 37% 21% 6%	627
April	1st to 10th	Night	21% 13% 36% 25% 5%	570
	11th to 20th	Night	20% 14% 30% 26% 10%	563
	21st to end	Night	23% 11% 31% 27% 7% 1	570
May	1st to 10th	Night	19% 8% 34% 31% 8% 1	570
	11th to 20th	Night	18% 5% 31% 35% 9% 1	561
	21st to end	Night	13% 5% 29% 35% 17% 2	617
June	1st to 10th	Night	11% 4 27% 43% 14% 1	570
	11th to 20th	Night	9% 2 29% 43% 15% 1	570
	21st to end	Night	10% 4 30% 39% 16% 1	570
July	1st to 10th	Night	10% 2 15% 38% 30% 4	555
	11th to 20th	Night	6% 3 21% 42% 26% 2	552
	21st to end	Night	7% 1 16% 46% 29% 1	624
August	1st to 10th	Night	8% 2 17% 43% 25% 5%	567
	11th to 20th	Night	7% 2 16% 42% 29% 5%	564
	21st to end	Night	7% 2 18% 39% 32% 2	627
September	1st to 10th	Night	12% 4 18% 37% 26% 2	570
	11th to 20th	Night	10% 3 18% 37% 26% 5%	610
	21st to end	Night	10% 9% 24% 33% 22% 2	760
October	1st to 10th	Night	12% 7% 29% 32% 18% 2	760
	11th to 20th	Night	19% 12% 29% 29% 11% 1	760
	21st to end	Night	24% 13% 34% 22% 7%	836
November	1st to 10th	Night	15% 11% 40% 25% 9% 1	755
	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 2024-11-01 21:47:34. Version ac07

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