Astroclimatology of Paranal

Nighttime Excursion Annual Statistics (85-99) Cold Nights Statistics (85-99) Monthly Statistics (97-99) Annual Plots ( 2000 1999 1998 1997 1996 1995 1994 1993 1990 1989 1988 1986 1985)

Temperature at Paranal: Nighttime Excursion (1998-2000)

Annual and Seasonal Statistics (2000-2006) and Nighttime variability. Hourly gradients surface and ground

Temperature at Paranal: Annual Statistics (85-06)

Nighttime (0-10hUT) 20mn Temperature Bins at 10m above ground

Year \ Celcius	Minimum	Average	Maximum	RMS
2006	1.9	12.9	23.2	2.5
2005	-10.3	12.1	18.7	3.3
2004	0.8	12.2	19.3	2.8
2003	-0.5	13.1	20.2	2.6
2002	-7.2	12.2	18.4	3.1
2001	1.9	12.2	19.3	2.7
2000	-6.7	11.7	19.4	3.1
1999	-5.1	11.3	18.2	2.8
1998	-1.7	11.7	20.9	3.2
1997	-1.1	11.7	19.2	3.2
1996	-1.9	11.5	18.7	2.8
1995	-4.3	11.7	18.9	2.7
1994	0.3	12.1	19.0	2.8
1993	2.1	11.6	20.3	2.9
1992	*	*	*	*
1991	*	*	*	*
1990	-2.7	11.5	19.8	3.3
1989	-8.0	10.7	18.0	3.0
1988	-5.1	11.5	20.5	3.1
1987	*	*	*	*
1986	-0.2	11.6	18.8	2.5
1985	-5.2	11.2	19.0	3.1

Temperature at Paranal: Cold Nights Statistics (study for Giraffe Spectrograph)

A darktime temperature lower than +5C at Paranal during one hour or more occurs on an average 16 nights per year, out of which about 20% are not photometric. This gives 13 clear 'cold' nights per year on an average.
Note 1: the cold weather often occurs in a row of several (2 to 5) consecutive cold nights. Only 30% of the cold nights are 'singles'.
Note 2: cold weather occurrence is limited to a 6 month period (April-September).

Year \ Nr. Nights Total Singles Period (day of the year)

1999 15 7 145-308

1998 11 5 145-288

1997 14 4 132-292

1996 16 6 170-287

1995 11 5 187-276

1994 12 2 186-304

1993 17 5 133-277

1992 * * *

1991 * * *

1990 23 8 88-280

1989 24 4 118-257

1988 19 4 151-270

1987 * * *

1986 10 2 139-231

1985 20 6 127-251

Temperature at Paranal: Monthly Statistics (97-99)

Nighttime (0-10hUT) 20mn Temperature Bins

97/98/99 (Celcius)	Minimum	Average	Maximum	RMS
January	*/11.0/6.7	*/15.9/11.9	*/20.9/16.4	*/1.6/1.6
February	9.5/9.6/9.8	14.2/14.1/13.1	19.2/18.3/16.1	1.9/2.1/1.0
March	7.1/9.3/9.2	12.7/14.3/12.8	19.1/18.3/16.4	2.8/2.1/1.4
April	9.5/5.7/7.8	13.2/12.0/12.8	17.6/16.5/18.0	1.8/2.5/1.9
May	4.0/4.6/-5.0	11.4/12.0/11.0	19.0/17.9/16.3	3.7/3.1/3.6
June	1.7/-1.5/-5.9	8.7/10.1/9.9	13.8/14.8/17.7	2.5/3.0/3.5
July	4.1/5.3/-4.2	11.6/9.8/8.0	19.1/14.5/15.3	3.3/1.9/3.7
August	0.6/-1.7/4.5	10.1/8.7/11.7	18.6/15.5/17.7	3.9/3.3/2.6
September	7.0/1.1/5.2	12.2/9.6/10.5	18.4/16.7/14.7	2.2/3.3/2.0
October	-1.1/2.8/3.5	9.4/10.7/10.8	17.1/15.1/17.4	2.8/2.4/2.7
November	6.4/6.9/4.0	12.3/12.2/10.7	17.4/16.8/14.9	2.5/1.9/1.9
December	8.1/7.2/7.6	13.3/12.1/12.1	18.4/16.5/16.1	2.1/1.7/1.5

Year \ Nr. Nights	Total	Singles	Period (day of the year)
1999	15	7	145-308
1998	11	5	145-288
1997	14	4	132-292
1996	16	6	170-287
1995	11	5	187-276
1994	12	2	186-304
1993	17	5	133-277
1992	*	*	*
1991	*	*	*
1990	23	8	88-280
1989	24	4	118-257
1988	19	4	151-270
1987	*	*	*
1986	10	2	139-231
1985	20	6	127-251

Astroclimatology of Paranal

Temperature at Paranal: Nighttime Excursion (1998-2000)

Temperature at Paranal: Annual Statistics (85-06)

Temperature at Paranal: Cold Nights Statistics (study for Giraffe Spectrograph)

Temperature at Paranal: Monthly Statistics (97-99)

Temperature at Paranal: Yearly Plots