Jerome
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Jerome clear sky chart from 2005-11-06 to 2024-02-15.

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% 6% 3 6% 6% 4 5% 5% 6% 7% 40%	78400
	Night	13% 6% 2 5% 5% 3 5% 5% 5% 7% 43%	80675
Transparency	Day	42% 6% 11% 22% 16% 3	78119
	Night	39% 5% 12% 24% 17% 3	80475
Seeing	Day	21% 12% 26% 22% 13% 5%	13889
	Night	19% 11% 24% 31% 14% 2	23717

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% 6% 3 6% 7% 3 5% 5% 5% 6% 40%	2814
	11th to 20th	Day	11% 10% 4 8% 8% 4 4 4 4 5% 37%	2840
	21st to end	Day	14% 9% 3 7% 6% 4 5% 4 5% 7% 36%	3124
February	1st to 10th	Day	11% 8% 4 7% 6% 4 5% 5% 5% 7% 38%	1710
	11th to 20th	Day	15% 7% 4 6% 5% 3 5% 4 5% 6% 39%	1609
	21st to end	Day	16% 8% 3 6% 4 3 4 4 5% 6% 41%	1515
March	1st to 10th	Day	12% 5% 3 6% 4 3 4 4 4 6% 48%	1980
	11th to 20th	Day	13% 7% 3 7% 6% 3 5% 5% 4 6% 41%	1980
	21st to end	Day	16% 8% 4 7% 6% 2 5% 5% 5% 6% 36%	2178
April	1st to 10th	Day	9% 6% 4 6% 6% 4 6% 5% 6% 7% 41%	2122
	11th to 20th	Day	13% 6% 3 5% 5% 3 5% 4 5% 6% 46%	2134
	21st to end	Day	17% 5% 2 6% 6% 3 5% 4 6% 6% 39%	2228
May	1st to 10th	Day	16% 6% 3 6% 5% 4 5% 6% 5% 8% 36%	2340
	11th to 20th	Day	18% 7% 3 6% 6% 4 5% 5% 4 8% 34%	2301
	21st to end	Day	13% 5% 2 5% 7% 4 5% 6% 6% 9% 38%	2691
June	1st to 10th	Day	12% 4 2 4 5% 3 6% 6% 7% 9% 40%	2520
	11th to 20th	Day	11% 4 2 5% 6% 4 6% 7% 6% 11% 36%	2520
	21st to end	Day	9% 4 2 5% 6% 5% 6% 7% 8% 9% 41%	2520
July	1st to 10th	Day	9% 5% 3 7% 7% 4 7% 6% 6% 8% 39%	2454
	11th to 20th	Day	7% 5% 2 5% 6% 5% 7% 7% 8% 11% 38%	2340
	21st to end	Day	10% 5% 3 7% 6% 5% 7% 7% 7% 9% 34%	2547
August	1st to 10th	Day	10% 6% 3 7% 8% 5% 8% 7% 7% 8% 32%	2327
	11th to 20th	Day	12% 5% 2 6% 7% 4 6% 7% 7% 8% 35%	2287
	21st to end	Day	11% 5% 3 6% 6% 4 6% 6% 6% 9% 38%	2376
September	1st to 10th	Day	14% 6% 3 5% 5% 3 4 4 5% 7% 43%	2160
	11th to 20th	Day	12% 6% 3 4 4 4 5% 4 5% 7% 47%	2074
	21st to end	Day	18% 6% 2 6% 6% 3 5% 5% 5% 7% 38%	1926
October	1st to 10th	Day	15% 6% 3 5% 4 2 4 4 6% 7% 43%	1800
	11th to 20th	Day	16% 6% 3 5% 5% 3 4 4 5% 5% 46%	1800
	21st to end	Day	14% 5% 2 4 5% 2 4 5% 5% 6% 47%	1980
November	1st to 10th	Day	10% 5% 2 4 5% 3 4 3 5% 6% 53%	1857
	11th to 20th	Day	14% 6% 2 4 4 2 5% 4 6% 6% 46%	1624
	21st to end	Day	14% 5% 2 4 5% 3 4 4 5% 6% 47%	1520
December	1st to 10th	Day	16% 8% 3 5% 5% 4 6% 5% 5% 7% 37%	1520
	11th to 20th	Day	14% 6% 2 5% 5% 3 4 5% 5% 7% 45%	1910
	21st to end	Day	17% 7% 2 6% 5% 4 6% 6% 6% 7% 35%	2772
January	1st to 10th	Night	10% 7% 3 4 5% 3 5% 6% 5% 8% 43%	4127
	11th to 20th	Night	14% 9% 3 5% 4 2 4 5% 5% 6% 43%	4120
	21st to end	Night	18% 9% 3 5% 5% 3 4 4 5% 6% 40%	4532
February	1st to 10th	Night	11% 7% 3 6% 6% 3 5% 6% 5% 7% 42%	2470
	11th to 20th	Night	15% 7% 3 7% 5% 3 5% 5% 6% 6% 39%	2332
	21st to end	Night	15% 8% 3 6% 6% 3 5% 6% 6% 6% 37%	1735
March	1st to 10th	Night	11% 4 2 4 4 3 5% 5% 5% 6% 50%	1980
	11th to 20th	Night	15% 6% 2 5% 5% 4 5% 5% 4 6% 43%	1980
	21st to end	Night	15% 6% 3 5% 4 3 5% 4 5% 7% 41%	2178
April	1st to 10th	Night	12% 7% 3 6% 5% 3 5% 6% 5% 7% 41%	1837
	11th to 20th	Night	11% 6% 2 6% 5% 3 4 5% 5% 8% 45%	1775
	21st to end	Night	16% 5% 2 5% 5% 4 4 5% 4 7% 44%	1746
May	1st to 10th	Night	16% 5% 3 5% 6% 2 4 5% 6% 8% 41%	1620
	11th to 20th	Night	16% 7% 3 6% 5% 4 4 4 5% 6% 39%	1592
	21st to end	Night	13% 5% 2 5% 5% 3 4 5% 6% 10% 42%	1580
June	1st to 10th	Night	10% 5% 1 4 6% 3 5% 5% 6% 10% 46%	1440
	11th to 20th	Night	11% 7% 1 6% 5% 3 5% 6% 7% 9% 41%	1440
	21st to end	Night	9% 3 2 5% 5% 3 5% 6% 8% 10% 45%	1440
July	1st to 10th	Night	10% 5% 2 5% 5% 3 6% 6% 6% 10% 41%	1501
	11th to 20th	Night	7% 4 2 4 5% 3 5% 6% 7% 10% 46%	1620
	21st to end	Night	7% 4 2 4 6% 3 6% 6% 7% 11% 42%	1771
August	1st to 10th	Night	8% 5% 2 5% 6% 3 6% 6% 7% 9% 42%	1611
	11th to 20th	Night	10% 5% 3 5% 7% 3 6% 5% 6% 8% 42%	1598
	21st to end	Night	9% 5% 3 6% 6% 4 5% 6% 6% 11% 40%	1975
September	1st to 10th	Night	13% 6% 2 5% 5% 3 4 5% 5% 7% 46%	1800
	11th to 20th	Night	11% 5% 3 3 4 3 4 3 6% 7% 50%	1882
	21st to end	Night	18% 7% 2 4 4 3 4 4 4 6% 43%	2034
October	1st to 10th	Night	18% 6% 2 4 4 2 4 4 5% 6% 45%	2160
	11th to 20th	Night	13% 5% 2 5% 4 3 3 4 5% 6% 50%	2160
	21st to end	Night	14% 6% 2 4 4 2 3 4 5% 6% 49%	2376
November	1st to 10th	Night	10% 5% 3 5% 4 3 3 4 4 6% 52%	2221
	11th to 20th	Night	13% 6% 3 4 4 2 4 4 5% 7% 49%	2553
	21st to end	Night	13% 4 2 5% 5% 3 6% 4 5% 7% 46%	2660
December	1st to 10th	Night	14% 7% 3 6% 5% 3 5% 4 5% 7% 40%	2660
	11th to 20th	Night	13% 6% 3 5% 4 3 6% 5% 4 7% 44%	3285
	21st to end	Night	15% 6% 2 6% 5% 4 6% 6% 6% 8% 35%	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	44% 4 6% 25% 16% 4	2815
	11th to 20th	Day	50% 4 7% 17% 17% 5%	2840
	21st to end	Day	47% 5% 8% 21% 16% 2	3124
February	1st to 10th	Day	45% 5% 11% 22% 14% 3	1710
	11th to 20th	Day	47% 4 9% 21% 17% 4	1618
	21st to end	Day	44% 4 12% 19% 17% 4	1515
March	1st to 10th	Day	38% 4 10% 24% 20% 3	1980
	11th to 20th	Day	44% 5% 10% 19% 18% 5%	1980
	21st to end	Day	48% 5% 10% 18% 14% 5%	2178
April	1st to 10th	Day	40% 6% 10% 19% 18% 7%	2122
	11th to 20th	Day	39% 4 10% 21% 21% 6%	2134
	21st to end	Day	45% 5% 10% 21% 15% 4	2228
May	1st to 10th	Day	45% 6% 13% 21% 13% 2	2340
	11th to 20th	Day	49% 6% 13% 19% 11% 3	2305
	21st to end	Day	44% 6% 15% 24% 11% 1	2691
June	1st to 10th	Day	39% 7% 12% 25% 15% 1	2520
	11th to 20th	Day	41% 9% 14% 20% 14% 2	2520
	21st to end	Day	36% 8% 14% 26% 13% 2	2520
July	1st to 10th	Day	43% 7% 12% 22% 14% 3	2387
	11th to 20th	Day	37% 8% 16% 24% 13% 2	2271
	21st to end	Day	43% 8% 12% 20% 16% 2	2405
August	1st to 10th	Day	46% 8% 13% 22% 10%	2314
	11th to 20th	Day	43% 7% 14% 22% 12% 1	2287
	21st to end	Day	42% 6% 14% 24% 12% 2	2376
September	1st to 10th	Day	41% 5% 13% 18% 19% 3	2160
	11th to 20th	Day	37% 5% 8% 27% 19% 4	2074
	21st to end	Day	46% 5% 9% 21% 18% 2	1926
October	1st to 10th	Day	40% 6% 10% 24% 17% 4	1800
	11th to 20th	Day	40% 4 9% 24% 20% 3	1800
	21st to end	Day	37% 5% 7% 25% 20% 5%	1980
November	1st to 10th	Day	33% 3 10% 26% 24% 5%	1857
	11th to 20th	Day	38% 4 10% 21% 23% 5%	1624
	21st to end	Day	38% 4 11% 25% 20% 2	1520
December	1st to 10th	Day	46% 5% 11% 23% 13% 2	1520
	11th to 20th	Day	38% 5% 10% 29% 14% 5%	1906
	21st to end	Day	45% 6% 13% 24% 12% 1	2772
January	1st to 10th	Night	38% 5% 9% 25% 21% 3	4127
	11th to 20th	Night	40% 5% 10% 24% 17% 4	4120
	21st to end	Night	45% 5% 8% 24% 16% 2	4532
February	1st to 10th	Night	42% 4 12% 26% 15% 2	2470
	11th to 20th	Night	45% 4 8% 21% 17% 4	2334
	21st to end	Night	45% 6% 10% 21% 13% 4	1735
March	1st to 10th	Night	34% 5% 10% 30% 17% 4	1980
	11th to 20th	Night	43% 5% 10% 22% 18% 3	1980
	21st to end	Night	41% 5% 13% 21% 16% 5%	2178
April	1st to 10th	Night	41% 6% 10% 21% 17% 4	1837
	11th to 20th	Night	37% 5% 12% 23% 18% 5%	1775
	21st to end	Night	40% 5% 11% 26% 14% 3	1746
May	1st to 10th	Night	41% 5% 14% 23% 13% 4	1620
	11th to 20th	Night	46% 6% 13% 21% 13% 1	1593
	21st to end	Night	38% 7% 18% 25% 10% 1	1581
June	1st to 10th	Night	34% 7% 14% 29% 15% 1	1440
	11th to 20th	Night	38% 9% 15% 23% 14% 1	1440
	21st to end	Night	33% 7% 18% 24% 17% 2	1440
July	1st to 10th	Night	38% 8% 16% 21% 13% 3	1458
	11th to 20th	Night	31% 8% 18% 26% 14% 2	1566
	21st to end	Night	31% 9% 19% 27% 14%	1672
August	1st to 10th	Night	37% 8% 17% 25% 13% 1	1600
	11th to 20th	Night	39% 6% 17% 25% 13%	1598
	21st to end	Night	38% 8% 14% 27% 12% 2	1975
September	1st to 10th	Night	39% 6% 14% 20% 17% 4	1800
	11th to 20th	Night	33% 5% 10% 31% 19% 2	1882
	21st to end	Night	43% 4 9% 24% 19% 2	2034
October	1st to 10th	Night	40% 4 11% 25% 18% 2	2160
	11th to 20th	Night	35% 4 9% 28% 21% 2	2160
	21st to end	Night	35% 4 9% 24% 25% 3	2376
November	1st to 10th	Night	33% 4 11% 24% 23% 6%	2221
	11th to 20th	Night	36% 4 8% 25% 22% 5%	2553
	21st to end	Night	38% 4 11% 24% 19% 3	2660
December	1st to 10th	Night	44% 4 11% 25% 13% 3	2660
	11th to 20th	Night	40% 4 10% 24% 19% 4	3288
	21st to end	Night	43% 7% 14% 21% 14% 1	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	32% 24% 30% 10% 3 1	266
	11th to 20th	Day	36% 21% 30% 10% 3	270
	21st to end	Day	31% 25% 35% 7% 2	297
February	1st to 10th	Day	30% 26% 33% 9% 1	270
	11th to 20th	Day	42% 22% 33% 4	252
	21st to end	Day	38% 20% 26% 14% 2	314
March	1st to 10th	Day	29% 24% 24% 20% 3	420
	11th to 20th	Day	27% 24% 25% 17% 5% 2	420
	21st to end	Day	26% 19% 30% 17% 6% 1	462
April	1st to 10th	Day	24% 22% 27% 19% 7% 1	420
	11th to 20th	Day	23% 16% 27% 18% 11% 4	412
	21st to end	Day	27% 13% 32% 16% 9% 3	420
May	1st to 10th	Day	24% 16% 31% 15% 10% 4	423
	11th to 20th	Day	23% 13% 30% 23% 7% 4	447
	21st to end	Day	19% 7% 27% 22% 18% 7%	485
June	1st to 10th	Day	16% 11% 25% 28% 14% 6%	450
	11th to 20th	Day	18% 9% 26% 25% 16% 7%	450
	21st to end	Day	12% 7% 32% 27% 17% 4	450
July	1st to 10th	Day	13% 3 19% 29% 27% 9%	445
	11th to 20th	Day	8% 3 20% 32% 26% 11%	444
	21st to end	Day	13% 2 22% 28% 24% 11%	488
August	1st to 10th	Day	15% 5% 20% 27% 21% 13%	446
	11th to 20th	Day	14% 3 18% 27% 27% 12%	439
	21st to end	Day	12% 4 20% 27% 21% 16%	495
September	1st to 10th	Day	18% 7% 16% 24% 23% 12%	450
	11th to 20th	Day	15% 2 22% 28% 22% 10%	450
	21st to end	Day	25% 8% 22% 26% 14% 4	450
October	1st to 10th	Day	21% 5% 22% 29% 20% 4	450
	11th to 20th	Day	21% 14% 24% 26% 12% 2	450
	21st to end	Day	20% 16% 32% 20% 10% 2	495
November	1st to 10th	Day	19% 12% 31% 25% 10% 4	455
	11th to 20th	Day	24% 15% 31% 21% 8% 1	266
	21st to end	Day	28% 14% 38% 16% 3 1	180
December	1st to 10th	Day	27% 19% 40% 8% 4 1	180
	11th to 20th	Day	26% 21% 31% 17% 6%	180
	21st to end	Day	23% 16% 38% 18% 5% 1	198
January	1st to 10th	Night	23% 18% 32% 23% 3	760
	11th to 20th	Night	23% 16% 27% 30% 3	760
	21st to end	Night	20% 17% 34% 27% 1	836
February	1st to 10th	Night	17% 19% 30% 31% 3	760
	11th to 20th	Night	27% 23% 29% 20% 2	722
	21st to end	Night	26% 16% 33% 23% 2	592
March	1st to 10th	Night	21% 17% 33% 25% 4	720
	11th to 20th	Night	25% 18% 26% 23% 6% 1	720
	21st to end	Night	22% 15% 33% 22% 6% 1	792
April	1st to 10th	Night	22% 18% 28% 26% 7%	720
	11th to 20th	Night	18% 14% 29% 27% 11% 1	711
	21st to end	Night	21% 12% 26% 33% 9%	666
May	1st to 10th	Night	21% 8% 24% 30% 16% 2	540
	11th to 20th	Night	21% 5% 24% 33% 15% 1	531
	21st to end	Night	16% 3 19% 35% 23% 4	420
June	1st to 10th	Night	13% 2 21% 39% 23% 2	360
	11th to 20th	Night	15% 4 13% 43% 23% 2	360
	21st to end	Night	8% 3 19% 48% 21% 1	360
July	1st to 10th	Night	12% 2 11% 38% 29% 8%	408
	11th to 20th	Night	8% 1 10% 38% 38% 5%	522
	21st to end	Night	9% 2 13% 40% 31% 6%	591
August	1st to 10th	Night	12% 1 10% 39% 34% 4	537
	11th to 20th	Night	12% 2 10% 39% 32% 5%	534
	21st to end	Night	12% 3 11% 35% 34% 4	787
September	1st to 10th	Night	18% 3 13% 29% 32% 5%	720
	11th to 20th	Night	13% 3 16% 33% 31% 5%	720
	21st to end	Night	23% 4 18% 32% 21% 2	720
October	1st to 10th	Night	22% 6% 16% 31% 22% 3	720
	11th to 20th	Night	17% 12% 23% 33% 15% 1	720
	21st to end	Night	19% 13% 24% 32% 12% 1	792
November	1st to 10th	Night	14% 10% 26% 36% 12% 2	740
	11th to 20th	Night	20% 14% 25% 30% 10% 1	760
	21st to end	Night	19% 16% 26% 31% 8% 1	760
December	1st to 10th	Night	21% 16% 29% 26% 7% 1	760
	11th to 20th	Night	17% 13% 33% 33% 5%	760
	21st to end	Night	20% 15% 26% 36% 3	836

Page generated at 2024-02-12 06:35:35. Version ac07

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